[{"VolcanoId":"ak20","Vnum":313010,"Volcano":"Augustine","OfficialName":"Augustine Volcano","ParentVolcanoId":"ak20","ParentVolcano":"Augustine","AgeClass":"Historical","AgeSource":"Several historical eruptions.","Composition":"andesite","IsMonitored":true,"VolcanoType":"Central dome cluster","NvewsThreat":"Very High Threat","Description":"   From Miller et al (1998): \"Augustine Island, an 8 by 11 km island in lower Cook Inlet, is composed almost entirely of the deposits of Augustine Volcano.  Jurassic and Cretaceous sedimentary strata form a bench on the south side of the island and are overlain by granitoid glacial erratics and volcanic hyaloclastites.  The volcano consists of a central dome and lava flow complex, surrounded by pyroclastic debris.  The irregular coastline of Augustine Island is due to the repeated catastrophic collapse of the summit dome, forming debris avalanches down the flanks and into Cook Inlet.  At least 11 avalanches have occurred in the past 2000 years with an average recurrence interval of about 150-200 years (Beget and Kienle, 1992; Beget, 1986).\r\n   \"Augustine lies within the area of uplift resulting from the 1964 Alaska earthquake; 30-33 cm of uplift was measured on the northwest side of the island (Detterman, 1968).  A 25-meter-high, south-facing submarine scarp 3 km south of the island, of similar orientation to joint sets in sedimentary rocks of the Kamishak River area (on the Alaska Peninsula), is almost certainly of tectonic origin.\"","NameOrigin":"The volcanic peak on Augustine Island was named \"Mount San Augustine\" in an 1867 U.S. Coast and Geodetic Survey report, and \"Mount Chinabora\" on a 1928 U.S. Post Route map. Captain James Cook named the island \"Saint Augustine Island\" in 1778 because it was sighted on St. Augustine's Day (Orth, 1971). In recent years, the \"Saint\" has been dropped from the name of both the island and the volcano; the volcano's formal name is \"Augustine Volcano.\" Tebenkov (1852) called the island \"O[strov] Chernoburoy\", meaning \"black brown\" (Orth, 1971)."},{"VolcanoId":"ak124","Vnum":313020,"Volcano":"Iliamna","OfficialName":"Iliamna Volcano","ParentVolcanoId":"ak124","ParentVolcano":"Iliamna","AgeClass":"Holocene","AgeSource":"Holocene tephra mentioned in W\u0026K, Beget ~300 CyBP lahars.","Composition":"andesite","IsMonitored":true,"VolcanoType":"Stratovolcano","NvewsThreat":"High Threat","Description":"   From Miller et al (1998): \"Iliamna volcano is a broad, deeply dissected and highly altered, roughly cone-shaped mountain at the north end of a 5-km-long ridge trending N10W.  Most of the volcano is covered by perennial snow and ice and numerous glaciers radiate from the summit area.  Large avalanche deposits occur on the flanks of the volcano, particularly down the Umbrella Glacier on the southwest side of the volcano.\r\n   \"The volcano is a typical composite stratovolcano composed of interbedded andesite lava flows and pyroclastic rocks.  Steep, inaccessible 600-m-high headwalls along the southern and eastern flanks extend nearly to the summit exposing a cross section of the volcanic stratigraphy.\r\n   \"Iliamna is built on a basement of Jurassic granitic rocks of the Aleutian Range batholith (Detterman and Hartsock, 1966) that are juxtaposed against older, Lower Jurassic lava flows and pyroclastic rocks by the Bruin Bay fault, which lies several kilometers east of the summit.\"","NameOrigin":"Iliamna Volcano's name was first published by the Russians as \"S[opka] Ilymna\" (Tebenkov, 1852). This appears to be the volcano called \"Volcan de Miranda\" by the 1779 Don Ignacio Arteaga expedition, which was probably named in honor of Fernando Bernardo de Quiros y Miranda, the second officer of the vessel La Princesa. The nearby Iliamna Lake, according to G.C. Martin, gets its name from the name of a \"mythical great blackfish, supposed to inhabit this lake, which bites holes in the bidarkas of bad natives\" (Orth, 1971)."},{"VolcanoId":"ak231","Vnum":313030,"Volcano":"Redoubt","OfficialName":"Redoubt Volcano","ParentVolcanoId":"ak231","ParentVolcano":"Redoubt","AgeClass":"Historical","AgeSource":"Several historical eruptions.","Composition":"andesite","IsMonitored":true,"VolcanoType":"Stratovolcano","NvewsThreat":"Very High Threat","Description":"   From Miller et al (1998): \"Redoubt Volcano is a steep-sided cone about 10 km in diameter at its base and with a volume of 30-35 cubic kilometers.  The volcano is composed of intercalated pyroclastic deposits and lava flows and rests on Mesozoic granitic rocks of the Alaska-Aleutian Range batholith (Till and others, 1993; 1994).  It has been moderately dissected by the action of numerous alpine glaciers.  A 1.8-km-wide, ice-filled summit crater is breached on the north side by a northward-flowing glacier, informally known as the Drift Glacier, which spreads into a piedmont lobe in the upper Drift River Valley.  The most recently active vent is located on the north side of the crater at the head of the Drift glacier.  Holocene lahar deposits in the Crescent River and Drift River valleys extend downstream as far as Cook Inlet.\"","NameOrigin":"\"Redoubt Volcano\" is a translation of the Russian name \"Sopka Redutskaya (Tebenkov, 1852). According to Constantin Grewingk (1850), the Native name \"Ujakushatsch\" also means \"fortified place\" but it is difficult to determine if one name is derived from the other (Orth, 1971)."},{"VolcanoId":"ak95","Vnum":null,"Volcano":"Espenberg","OfficialName":null,"ParentVolcanoId":"ak95","ParentVolcano":"Espenberg","AgeClass":"Pleistocene","AgeSource":"Beget and others, 1996: Youngest maar in Espenberg maars is 17,500 ybp, oldest may be 100-200,000 years old.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Maars and basalt field","NvewsThreat":null,"Description":"   From Wood and Kienle (1990): \"These are among the northernmost volcanoes in North America, being just south of the Arctic Circle.  The basalt field contains 5 maars and 5 small shield-shaped volcanoes.  The shields are of Pleistocene age and form tundra-covered hills as tall as 240 m.  The maars are younger than the shields and range in age from \u003e0.12 Ma to ~7,000 yr.  The maars are 2 to 5 km in diameter and are filled by lakes with surfaces 60 to 80 m below surrounding topography and as much as 30 m deep.  Tholeiitic and alkalic basalt of the maars contains up to several tens of percent xenoliths of basement metamorphic and sedimentary rocks as well as masses of unconsolidated Quaternary sediments which must have been frozen at the time of eruption.\"","NameOrigin":"\"Espenberg maars\" is an informal name applied to the group of five maars and 5 shield volcanoes, near Cape Espenberg. Cape Espenberg was named in 1816 by Lt. Otto von Kotzebue for Dr. Karl Espenberg, a surgeon who accompanied Admiral A.J. von Kruzenstern on his voyage around the world in 1803-06 (Orth, 1971)."},{"VolcanoId":"ak326","Vnum":315020,"Volcano":"Wrangell","OfficialName":"Mount Wrangell","ParentVolcanoId":"ak326","ParentVolcano":"Wrangell","AgeClass":"SuspHist","AgeSource":"Suspected historical eruptions; dated flows all Pleistocene, one or two undated flows may be Holocene; see individual eruption center data.","Composition":"andesite","IsMonitored":true,"VolcanoType":"Shield volcano with summit caldera","NvewsThreat":"Moderate Threat","Description":"   From Miller and others (1998): \"Mount Wrangell is a large andesitic shield volcano with a volume of about 900 cubic kilometers (Nye, 1983).  Its top is capped by a 4 by 6 km, ice-filled summit caldera whose depth may exceed 1 km (Benson and Motyka, 1979).  The caldera is apparently of non-explosive origin (Richter and others, 1984) formed in response to the withdrawal of magma from high-level reservoirs beneath the summit area.  Three small (\u003c1 km in diameter) post-caldera craters, all geothermally active, occur along the west and north margin of the caldera.  Mt. Zanetti (3965 m) a large (450 m high) steep-sided, relatively undissected cinder-spatter cone occurs high on the northwest flank of the shield and may be the source of some lava flows.  Lavas on the southwest flank have flowed as much as 58 km from their source despite being phenocryst-rich andesite, a mobility attributed to a very high eruption rate (Nye, 1983).\"","NameOrigin":"Mount Wrangell was named by the Russians for Baron von Wrangell. This name was reported in 1885 by Lieutenant Allen, although it appears he named this mountain \"Tillman\" for Samuel Escue Tillman, professor at the U.S. Military Academy at West Point (Orth, 1971)."},{"VolcanoId":"ak90","Vnum":315040,"Volcano":"Edgecumbe","OfficialName":"Mount Edgecumbe","ParentVolcanoId":"ak90","ParentVolcano":"Edgecumbe","AgeClass":"Holocene","AgeSource":"Riehle says youngest eruptions 5,000 years old. Native oral history of eruptions 800 years ago.","Composition":null,"IsMonitored":true,"VolcanoType":"Stratovolcano","NvewsThreat":"Moderate Threat","Description":"   From Wood and Kienle (1990): \"The Edgecumbe volcanic field on southern Kruzof Island is on the North American plate 10-15 km inboard of the Queen Charlotte-Fairweather transform fault.  The Edgecumbe volcanic field is dominated by the symmetric stratovolcano of Mount Edgecumbe and the domes and crater of adjacent Crater Ridge.  Mount Edgecumbe was named by Captain James Cook in 1778.\"\r\n   \"The latest significant eruptive activity was postglacial and produced voluminous pyroclastic deposits (7.6 cubic km dense-rock equivalent).  The main geomorphic features of the Edgecumbe volcanic field were formed during this activity and include basaltic andesite scoria cones, a crater explosively reamed from the Crater Ridge domes during eruptions of rhyolitic pyroclastic flows, and eruption of andesite and dacite tephra during dome emplacement and crater formation on the Mount Edgecumbe cone.  Tephra deposits produced by the late Pleistocene-early Holocene activity of the Edgecumbe volcanic field have been found as far away as Juneau and Lituya Bay, 200 km to the north.  Vents active during the pyroclastic eruptions have a northeast-southwest alignment that probably marks a regional fissure.\"","NameOrigin":"Mount Edgecumbe was named in 1778 by Captain James Cook, \"probably after Mt. Edgecumbe at the entrance of Plymouth Harbor, England, or possibly after George, the first Earl of Edgecumbe. The name was adopted by Vancouver\" (Wagner, 1937). This feature was also called \"Montana de San Jacinto,\" or \"Saint Jacinto Mountain,\" on August 16, 1775, by Don Juan de la Bodega y Quadra, \"in honor of the saint whose day it was\" (Wagner, 1937). Lt. Sarychev (1826) called it \"Gora Svataya Lazarya,\" or \"Saint Lazarus Mountain (Orth, 1971)."},{"VolcanoId":"ak22","Vnum":315070,"Volcano":"Behm Canal volcanic field","OfficialName":null,"ParentVolcanoId":"ak22","ParentVolcano":"Behm Canal volcanic field","AgeClass":"SuspHolo","AgeSource":"Youngest flows possibly ~0.5 my (W\u0026K). For Painted Peak (part of this volcano), Berg and others (1988): K-Ar ages of Painted Peak show volcanism at about 5 Ma and between 1 and 0.4 Ma. However, Jim Baichtal (written commun., 2003) as well as Berg and others (1988) agree that this feature is post-glacial, meaning it is younger than 13,500 years, and therefore Holocene or Pleistocene, and not Tertiary.","Composition":"basalt","IsMonitored":false,"VolcanoType":"volcanic field","NvewsThreat":"Very Low Threat","Description":"   From Wood and Kienle (1990): \"Potassic alkali olivine basalt cinder cones and columnar-jointed flows occur as separate entities in the field, which is more or less centered on the Coast Range megalineament.  Minor andesite and trachyandesite flows are locally present.  There are also thin patches of ash and lapilli layers.  The lava flows unconformably overlie glacial-fluvial sand and silt deposits and granitic gneiss of the Coast Mountains plutonic-metamorphic complex.  Glacial striations and grooves indicate that some of the flows pre-date the last glaciation, but undissected cinder cones and flow surface features indicate that most of the activity was post-glacial.  Flows are locally columnar-jointed, and some tuff and breccia deposits form void-rich spires and cliffs.\"","NameOrigin":"\"Behm Canal volcanic field\" is an informal name applied to a group volcanic vents in the vicinity of Behm Canal."},{"VolcanoId":"ak161","Vnum":311020,"Volcano":"Kiska","OfficialName":"Kiska Volcano","ParentVolcanoId":"ak161","ParentVolcano":"Kiska","AgeClass":"Historical","AgeSource":"Historical eruptions at Sirius Point vents.","Composition":"andesite","IsMonitored":false,"VolcanoType":"Stratovolcano","NvewsThreat":"Moderate Threat","Description":"   From Miller and others (1998): \"Kiska Volcano is a stratovolcano, 8.5 by 6.4 km in diameter at its base and 1221 m high, on the northern end of Kiska Island.  A slightly elliptical crater, about 0.4 km in diameter and breached on the north, occupies the summit.  A parasitic 30-m-high cinder cone, formed in 1962 near sea level, occurs at Sirius Point and an older parasitic cone, now leveled by marine erosion, occurs at sea level 5.6 km southwest of Kiska Volcano.\r\n   \"The southern part of Kiska Island has been glacially eroded, but the volcano shows no evidence of glacial dissection (Coats, 1956).  Surface lava flows are thus younger than the last major glaciation.  Five of the youngest lava flows (unit Qkr) have been mapped separately by Coats and others (1961) based on geomorphic expression; the flows of block lava have steep fronts as much as 30 m high.  Source areas of the flows range from the base of the cone to the summit.  The highest flows appear to have emerged from the summit crater through the breached north wall.\r\n   \"Kiska Volcano is underlain and flanked on the south by the remains of an older composite volcano; a single K-Ar age of 5.5 +/- 0.7 m.y. is cited in Marlow and others (1973) for an andesitic lava flow in this older volcano.\"","NameOrigin":"Kiska Volcano was named after Kiska Island. \"Kiska Island\" is an Unangax name used by the early Russians. Baker (1906), cites W.H. Dall, as giving the meaning as \"gut,\" but Geoghegan (1944) gives the word \"angig\" with that meaning. Golder (1922) identifies Kiska with the island seen by Vitus Bering on October 25, 1741, and named by him \"St. Markiana.\" Others have correlated Kiska with Bering's \"St. Stephen\" (Orth, 1971)."},{"VolcanoId":"ak247","Vnum":311030,"Volcano":"Segula","OfficialName":"Segula Peak","ParentVolcanoId":"ak247","ParentVolcano":"Segula","AgeClass":"SuspHist","AgeSource":"Nelson (1959) considered the most recent lava flows on Segula to be no more than a few hundred years old.","Composition":"unknown","IsMonitored":false,"VolcanoType":"Stratovolcano","NvewsThreat":"Low Threat","Description":"   From Wood and Kienle (1990): \"Segula volcano is built upon a 100-m-deep marine platform by the accumulation of flows and pyroclastic material emanating from a single center.  Although there are no dated eruptions, some flows and pyroclastic deposits are so little weathered that ages of only a few hundred years are estimated.  Pyroclastic material covers much of the cone's surface and a cinder cone resides in the middle of the summit crater.\"","NameOrigin":"\"Segula Peak\" was published on a 1951 U.S. Geological Survey map. W.H. Nelson (1959) called it \"Segula Volcano\" (Orth, 1971)."},{"VolcanoId":"ak73","Vnum":311040,"Volcano":"Davidof","OfficialName":"Davidof Island","ParentVolcanoId":"ak73","ParentVolcano":"Davidof","AgeClass":"SuspHolo","AgeSource":"Smith and others (1978) suggest Holocene for Davidof.","Composition":"unknown","IsMonitored":false,"VolcanoType":"Caldera remnant","NvewsThreat":"Low Threat","Description":"   From Wood and Kienle (1990): \"Davidof, Khvostof, and nearby small islands Pyramid and Lopy rise 100 m above a submarine platform as the remnants of a collapsed caldera.  This 'Aleutian Krakatoa' is thought to have formed during the late Tertiary, but the volcano is essentially unstudied.  The islands are covered by vegetation; however lava flows can be recognized on aerial photographs.  Lavas and pyroclastic layers form the islands, and rocks on the northern part of Davidof and Lopy Island are intensely hydrothermally altered.\"","NameOrigin":"Davidof Island's name was published by Admiral von Krusenstern (1827), for the Russian naval officer Gavriil Ivanovich Davidov, who, with N.A. Khvostov, explored Alaska during 1802-1804. Admiral von Kruzenstern applied the name \"I[sle] Dawydoff\" to Segula Island, but in 1855 the U.S. Navy Hydrographic Office clarified the size and position of both Davidof and Segula Islands and reapplied the names (Orth, 1971)."},{"VolcanoId":"ak182","Vnum":311050,"Volcano":"Little Sitkin","OfficialName":"Little Sitkin Island","ParentVolcanoId":"ak182","ParentVolcano":"Little Sitkin","AgeClass":"SuspHist","AgeSource":"Snyder (1959) mapped flows on the south and west flanks that he considered to be similarly-aged to a 1906 flow on nearby Kanaga.","Composition":"andesite","IsMonitored":true,"VolcanoType":"Stratovolcano within nested calderas","NvewsThreat":"Moderate Threat","Description":"   From Miller and others (1998): \"The active stratovolcano on Little Sitkin Island occurs within the eroded remnants of a nested double caldera of probable late Pleistocene age.  The older caldera (Caldera One) is about 4.8 km in diameter and is centered slightly northeast of the island's midpoint.  The caldera formed at the site of a large stratovolcano, the remnants of which are the oldest rocks exposed on the island (unit Qtw; Snyder, 1959).\r\n   \"A second stratovolcano was constructed almost entirely of lava flows (unit Qd) within Caldera One and attained a height of about 900 m.  A cataclysmic eruption, possibly in early post-glacial time, resulted in the formation of a second, smaller caldera (Caldera Two) that partially destroyed this cone.  Caldera Two is elliptical in outline and measures 2.7 by 4 km; the inferred eastern and southern margins are coincident with those of Caldera One.  Field relations suggest that the northern boundary of Caldera Two is a hinge along which a large block, comprising most of the Caldera One stratovolcano, was tilted southward during the caldera eruption.  The highest peak on the island is on the post-caldera remnant of the second cone.\r\n   \"A deposit of partly welded tuff up to 100 m thick (unit Qp) extends from the remnant cone northwest across the Caldera Two boundary fault, to slightly beyond the inferred location of the Caldera One boundary fault.  The deposit is thought to have been emplaced by one of more pyroclastic flows, possibly associated with formation of Caldera Two (Snyder, 1959).\r\n   \"Post-Caldera Two deposits are mainly lava flows (units Qls, Qlp, and Qlw).  Two relatively recent aa flows have well developed levees; one originated from the breached central crater of Little Sitkin volcano, and the other from a fissure along the western trace of the Caldera One boundary fault (Snyder, 1959).\"","NameOrigin":"The island of Little Sitkin was named \"O[strov] Malyy Sitkhin,\" meaning \"little Sitkin island\" on the 1848 Russian Hydrographic Department Chart 1400. The name \"Sitkin\" may possibly be from the Unangam Tunuu word \"sixtan,\" which, according to R.H. Geoghegan, means \"from beneath or from under\" (Orth, 1971). Bergsland (1994) translates this word as \"dung\" or \"defecator.\""},{"VolcanoId":"ak248","Vnum":311060,"Volcano":"Semisopochnoi","OfficialName":"Semisopochnoi Island","ParentVolcanoId":"ak248","ParentVolcano":"Semisopochnoi","AgeClass":"Historical","AgeSource":"Historical eruptions from Cerberus, possible eruptions from Sugarloaf Peak.","Composition":"mafic","IsMonitored":true,"VolcanoType":"Intracaldera stratocones","NvewsThreat":"High Threat","Description":"   From Wood and Kienle (1990): \"Semisopochnoi is the largest young volcanic island in the western Aleutians and is composed of a variety of volcanic landforms.  Basaltic pyroclastic material built a shield of ~20 km wide (at sea level) which culminated in a post-glacial pumice and ash eruption of dacite and andesite, producing an 8-km-wide caldera.  Smaller composite cones are both pre- and post-glacial.  Mount Cerberus is the most active of the three younger cones within the caldera.  These young cones are dominantly two-pyroxene, high-alumina basalt, and andesite.  One young composite cone (Sugarloaf) has olivine basalt.  Dacite and andesite are found among the eruptive products of the pre caldera shield.  Much of the island is covered by basaltic to andesitic ash derived from the younger cones.  Semisopochnoi's tholeiitic differentiation trend (iron is enriched as silica increases) and relatively large volume are common in volcanoes near segment boundaries.  Semisopochnoi is also on a small submarine ridge that extends northward as a part of the scorpion-tail-shaped Bower's Ridge; it is unclear if this setting influences its volcanism.\r\n   \"An historic eruption of Semisopochnoi was reported in 1873, and at least four others may have occurred in the previous hundred years, but documentation is scanty.  These eruptions apparently emanated from the flanks of Mount Cerberus; the most recent flow appears to be less than a century old.\"","NameOrigin":"\"Semisopochnoi Island\" was published by Lieutenant Sarichev (1826) as \"O[strov] Semisopochnyy\" (Semisopochnoi Island) (Orth, 1971). While there are seven prominent peaks on Semisopochnoi, there are numerous active volcanic vents."},{"VolcanoId":"ak106","Vnum":311070,"Volcano":"Gareloi","OfficialName":"Mount Gareloi","ParentVolcanoId":"ak106","ParentVolcano":"Gareloi","AgeClass":"Historical","AgeSource":"Historical eruptions.","Composition":"basalt","IsMonitored":true,"VolcanoType":"Stratovolcano","NvewsThreat":"Moderate Threat","Description":"   From Miller and others (1998): \"Mount Gareloi, which makes up most of Gareloi Island, is a stratovolcano 10 km by 8 km in diameter at its base with two summits, separated by a narrow saddle.  Two small glaciers extend northwest and southeast from the saddle.  The northern, slightly higher peak is on the southern rim of a crater about 300 m across, which contains several active fumaroles.  Thirteen younger craters, from 80 to 1600 m in diameter, are aligned along a south-southeast trending fissure that extends from strandline to the southern summit.  These craters formed during a major explosive eruption in 1929 that also produced four blocky lava flows (unit Ql), and a blanket of grassy andesitic tuff that covers an area roughly 2.5 x 5 km on the volcano's southeast flank (Coats, 1959).\r\n  \"The intercalated lava flows and pyroclastic debris that make up Gareloi volcano were produced during two periods of activity separated by an extended interval of quiescence and erosion.  Lava flows range from 1 m to more than 6 m in thickness; some flows of the older sequence appear to have originated from flank vents rather than from the summit.  Some valleys cut in older rocks are U-shaped, suggesting that the older series is of late Pleistocene age or older.  Rocks of the younger series are relatively undissected; many appear to have been erupted form at or near the summit crater.  Craters formed during the 1929 eruptions are probably only partly of phreatic origin; erupted material included essential, pumiceous glass, and reddened scoria.  Lava flows that erupted in 1929 emerged at elevations below 600 m.  In 1949, one crater at an elevation of 900 m, contained a small, milky blue-green lake, which suggests that acid fumaroles were still active in the crater at that time (Coats, 1959, p. 253).\"","NameOrigin":"Mount Gareloi is named after Gareloi Island. Gareloi Island's name was published as \"O[strov] Goreloi,\" or \"Goreloi Island\" by Lt. Sarychev (1826), from the Russian word for \"burnt\" or \"burning.\" According to Captain Tebenkov (1852), its Unangam Tunuu name was \"Anangusik.\" The name \"Gareloi\" appeared on U.S. and British maps prior to 1902 (Orth, 1971)."},{"VolcanoId":"ak111","Vnum":311120,"Volcano":"Great Sitkin","OfficialName":"Great Sitkin Volcano","ParentVolcanoId":"ak111","ParentVolcano":"Great Sitkin","AgeClass":"Historical","AgeSource":"Historical eruptions.","Composition":"mafic","IsMonitored":true,"VolcanoType":"Stratovolcano with caldera and dome","NvewsThreat":"High Threat","Description":"   From Miller and others (1998): \"Great Sitkin Volcano occupies most of the northern half of Great Sitkin Island, a member of the Andreanof Islands group in the central Aleutian Islands.  The volcano is roughly oval-shaped, 8 by 11 km at the base, with the long axis trending east-west.  It is a composite structure consisting of the remains of an older, decapitated volcano and a younger parasitic cone that collapsed forming a small caldera (0.8 by 1.2 km) on the west flank (Simons and Mathewson, 1955).  The highest point on the island is apparently a remnant of the former central volcano's eastern rim.  Most of the constructional surface of the cone has been deeply eroded.  A steep-sided, recently emplaced dome (unit Qgd) occupies the center of the caldera at an elevation of 1220 m.  The dome is 183 m high, 0.4 km wide, and 0.6 km long with a blocky, flat top.  Five small plugs (unit Qa) are intruded into the northwest slope of the cone; three of the plugs are aligned in a northwest direction from the crater, and the remaining two are aligned north-northwest.\r\n   \"Rocks that comprise the main cone are named the Great Sitkin volcanics (unit Tgc), and consist of andesite and basalt lava flows interbedded with tuff beds (Simons and Mathewson, 1955).  Lava flows predominated on the upper part of the cone, which has undergone extensive glacial erosion; construction of the cone may have begun in late Tertiary or early Quaternary time and was apparently completed before the end of Pleistocene glaciation.  Partila destruction of the cone's former peak was followed by a westward shift in eruptive activity.  A parasitic cone was built and subsequently destroyed during caldera-forming eruptions of unknown age.  Pumice, scoria, and rock fragments from this eruption blanket the island to depths of a few centimeters to more than 6 m.  Overlying the pumice deposit on the northwest flank of the main cone is an ash deposit that was apparently erupted from a subsidiary vent located immediately northwest of the crater (Simons and Mathewson, 1955).  A glacially truncated, columnar jointed basalt flow occurs low on the south flank of the main cone near the head of Sitkin Creek (unit Tgs).  This flow is the product of a flank eruption, the source of which is covered by pumice (Simons and Mathewson, 1955, p. 31).\r\n   \"Great Sitkin volcano is built upon the eroded remnants of a late Tertiary shield volcano, which forms more of the southern half of the island.  The undeformed succession, termed the Sand Bay  volcanics by Simons and Mathewson (1955), consists of pyroclastic rocks, mainly volcanic breccias, which are overlain by a sequence of andesite and basalt lava flows.  The succession crops out in a gently dipping radial pattern suggesting a source near the present cone.\r\n   \"The Sand Bay volcanics unconformably overlie the Finger Bay volcanics, an older, highly altered and deformed sequence of lava flows, breccia, and tuff that form the rugged headlands along the southern and southeastern coasts.  By correlation with nearby Adak Island, the Finger Bay volcanics are probably no younger than late Eocene in age, and may be as old as Cretaceous (Scholl and others, 1970).\"","NameOrigin":"Great Sitkin Volcano is named for Great Sitkin Island. Bergsland (1994) says the Unanagan name for Great Sitkin means \"defecator\".  Great Sitkin Island's Unangam Tunuu name was published by the Russians as \"O[strov] Sitkhin.\" or \"Sitkhin Island\" (Sarychev, 1826). Dall (1880) called the island \"Great Net Island\" (Orth, 1971)."},{"VolcanoId":"ak168","Vnum":311140,"Volcano":"Koniuji","OfficialName":"Koniuji Island","ParentVolcanoId":"ak168","ParentVolcano":"Koniuji","AgeClass":"Holocene","AgeSource":"Jicha and Singer (2009) obtained new 40Ar/39Ar age dates on Koniuji ranging between 15.2 to 3.1 ka, with one undateable sample that is stratigraphically younger than the 3.1 ka sample.","Composition":"andesite","IsMonitored":false,"VolcanoType":"Stratovolcano","NvewsThreat":"Low Threat","Description":"    From Jicha and Singer (2009): Jicha and Singer were able to spend two days on Koniuji during the summer of 2008, while accompanying the USFWS vessel Tiglax. While on Koniuji, they collected samples for 40Ar/39Ar dating. Koniuji is a nascent stratovolcano, with 40Ar/39Ar ages that indicate subaerial lavas and domes erupted over the last 15,000 years, including at least three eruptions within the last 6000 years. It has an estimated volume of 1 cubic km, with approximately 25% of that volume subaerial. Dated products include older basaltic andesite lavas and younger andesite dome rocks. \r\n   Wood and Kienle (1990) note that in 1981, \"geologists from the USGS research vessel S.P. Lee landed in a small boat to collect samples. The collected rocks are from andesite flows, and pyroclastic deposits. A northeast-trending fault cuts the island on the southeast. A possible vent occurs just north of the highest point on the island.\"","NameOrigin":"Koniuji Island is named for the great number of crested auks called \"Kanoozkhi\" or \"Kanooskie\" by the early Russians, and which the Unangax call \"Kunuliuk.\" Lieutenant Sarichev published the name as \"O[strov] Kanyugi\" in 1826 (Orth, 1971)."},{"VolcanoId":"ak249","Vnum":311150,"Volcano":"Sergief","OfficialName":"Mount Sergief","ParentVolcanoId":"ak249","ParentVolcano":"Sergief","AgeClass":"SuspPleist","AgeSource":"Sergief's age is not known. Hein and others (1984) says not Quaternary, but rather late Eocene to middle Oligocene!","Composition":"mafic","IsMonitored":false,"VolcanoType":"Stratovolcano","NvewsThreat":null,"Description":"   From Smithsonian Institution, online database, accessed December 8, 2003: \"Sergief is a small stratovolcano on SW Atka Island whose age is poorly known. The SW part of the island is older and less topographically rugged than the NE part of the island. Sergief was tentatively listed as a young volcano in the Post-Miocene Volcanoes of the World catalog of the International Association of Volcanology and Chemistry of the Earth's Interior (1973), but the age of its latest eruption is not precisely known.\"","NameOrigin":"This volcano was called \"Sergheieff\" by Lutke (1836). The name \"Mount Sergief\" was published by Coats (1950), but applied to a peak in a different location. A 1952 U.S. Geological Survey topographical map shows Mount Sergief as being on western Atka Island near Sergief Bay (Orth, 1971)."},{"VolcanoId":"ak246","Vnum":311180,"Volcano":"Seguam","OfficialName":"Seguam Island","ParentVolcanoId":"ak246","ParentVolcano":"Seguam","AgeClass":"Historical","AgeSource":"Historical eruptions from Pyre Peak vent.","Composition":"mafic","IsMonitored":false,"VolcanoType":"Stratovolcano within caldera (?)","NvewsThreat":"High Threat","Description":"   From Miller and others (1998): \"Seguam Island consists of the remnants of two late Quaternary calderas.  Holocene volcanic cones occur in both of the calderas and a third Holocene cone lies at the east end of the island.  Pyre Peak, commonly referred to as Sequam volcano, highest of the young cones, dominates the western half of the island and occupies the center of the western caldera (Singer and others, 1992) that is defined by remnants of a semi-circular ridge about 3 km in original diameter and about 700 m high.  A Holocene basalt field surrounds Pyre Peak (Singer and others, 1992) extending down to shoreline.  This general area has been the site of most if not all historical volcanic activity.  Late Quaternary lavas and pyroclastic rocks ranging in age from 1.1 Ma to 0.03 Ma underlie the basalt.  The two Holocene cones to the east are surrounded by andesite and dacite lava flows with well preserved constructional features (Singer and others, 1992).\"","NameOrigin":"Seguam Island was called \"Ostrov Seguam\" by Lieutenant Sarichev, from an Unangam Tunuu name. Lutke called it \"Segouam ile\" and \"Gorely Ile (1836). \"Goreli\" is Russian for \"burnt\" (Orth, 1971)."},{"VolcanoId":"ak10","Vnum":311190,"Volcano":"Amukta","OfficialName":"Amukta Island","ParentVolcanoId":"ak10","ParentVolcano":"Amukta","AgeClass":"Historical","AgeSource":"Historical eruptions.","Composition":"unknown","IsMonitored":false,"VolcanoType":"Stratovolcano","NvewsThreat":"Moderate Threat","Description":"   From Miller and others (1998): \"The undissected stratovolcano of Amukta volcano composes most of nearly circular, 7.7-km-wide Amukta Island.  The cone, about 5.8 km in basal diameter and topped by a 0.4 km wide summit crater, appears on synthetic-aperture radar imagery to be built on a 300+ meter high, east-west trending arcuate ridge.  Extensions of that ridge on the southwest and east sides of the island indicate an older caldera approximately 6 km in diameter and open to the sea on the south side.  No hot springs or fumaroles have been reported from Amukta.  Sekora (1973, p. 29) reports the presence of a cinder cone near the northeastern shore of the island.\"","NameOrigin":"\"Amukta volcano\" is an informal name given to the peak on Amukta Island. The name Amukta (referring to the island) was reported in 1768 by Captain Lt. P.K. Krenitzin and Lt. M. Levashev (Orth, 1971)."},{"VolcanoId":"ak46","Vnum":311200,"Volcano":"Chagulak","OfficialName":"Chagulak Island","ParentVolcanoId":"ak46","ParentVolcano":"Chagulak","AgeClass":"SuspHolo","AgeSource":"Little is known of Chagulak, it is suspected to be of Holocene age.","Composition":"unknown","IsMonitored":false,"VolcanoType":"Stratovolcano","NvewsThreat":"Low Threat","Description":"   From Wood and Kienle (1990): \"Chagulak is a small stratovolcano separated from Amukta by ~7 km of ocean, but the two coalesce at depth.  Chagulak is unstudied; the only geologic information available is a single chemical analysis.  A low-potassium, high-alumina basaltic andesite (51% SiO2, 0.59% K2O) was recovered from the north-northwest shore of the island, but the sample's geologic setting is unknown.\"","NameOrigin":"The U.S. Coast and Geodetic Survey gave the Unangam Tunuu name \"Chagulak\" to Chagulak Island in 1931, to avoid repeating the name \"Chugul.\" This island was called \"O[strov] Chugula\" by Lt. Sarychev (1826) (Orth, 1971)."},{"VolcanoId":"ak40","Vnum":311230,"Volcano":"Carlisle","OfficialName":"Carlisle Island","ParentVolcanoId":"ak40","ParentVolcano":"Carlisle","AgeClass":"Historical","AgeSource":"Carlisle has several poorly documented eruption accounts.","Composition":"unknown","IsMonitored":false,"VolcanoType":"Stratovolcano","NvewsThreat":"Low Threat","Description":"   From Miller and others (1998): \"Carlisle Island consists of a single symmetric cone, 1524 m high and 6.5 km in diameter at sea level;  its steep upper slopes are generally snow-covered year round.  Little is known about Carlisle volcano's structure and composition.  The topography suggests that the lower slopes of Carlisle are slightly more irregular in form and more dissected by erosion than are the uppermost slopes.  According to Sekora (1973), the western margin of the island consists of a small plateau at an elevation of 50 m, suggesting that the Carlisle stratovolcano is constructed on an emergent marine terrace.\"","NameOrigin":"Carlisle Island was named in 1894 by the U.S. Navy Hydrography Office, for John G. Carlisle, Secretary of the Treasury (Orth, 1971)."},{"VolcanoId":"ak297","Vnum":311250,"Volcano":"Uliaga","OfficialName":"Uliaga Island","ParentVolcanoId":"ak297","ParentVolcano":"Uliaga","AgeClass":"SuspPleist","AgeSource":"Little is known of Uliaga, it is suspected to be of Holocene age.","Composition":"unknown","IsMonitored":false,"VolcanoType":"Stratovolcano","NvewsThreat":"Low Threat","Description":"   From Wood and Kienle (1990): \"Uliaga is a triangular-shaped island composed of an eroded stratovolcano.  No evidence of a caldera is seen, but little is known geologically about this volcano.\"","NameOrigin":"\"Uliaga Island' is an Unangam Tunuu name, reported by the U.S. Navy Hydrographic Office in 1894 (Orth, 1971)."},{"VolcanoId":"ak142","Vnum":311260,"Volcano":"Kagamil","OfficialName":"Kagamil Volcano","ParentVolcanoId":"ak142","ParentVolcano":"Kagamil","AgeClass":"SuspHist","AgeSource":"Kagamil has poorly documented early historical eruption accounts, as well as active fumaroles and hot springs.","Composition":"unknown","IsMonitored":false,"VolcanoType":"Stratovolcano","NvewsThreat":"Moderate Threat","Description":"   From Miller and others (1998): \"Kagamil volcano occupies most of the southern half of Kagamil Island, 55 km west of Umnak Island in the eastern Aleutian arc.  The volcano consists of two cones and has an oval shape, 3.5 by 2 km in basal dimensions, with the long axis trending northwest-southeast.  The larger cone at the southeastern end of the volcano has an elevation of 893 m; the cone at the northwestern end is about 610 m high and appears to have two small summit craters.  Hot springs and fumaroles occur near the southeastern shore of the island (Sekora, 1973).\r\n   \"Both cones appear to be virtually undissected by erosion, indicating a post-glacial age.  The cones rise from a more gently sloping surface with mean elevation of about 200 m.\"","NameOrigin":"Kagamil Volcano is named for Kagamil Island. Kagamil Island is an Unangam Tunuu name applied to this island by Captain Tebenkov in 1852. This island was called \"O[strov] Chuginok\" or \"Chuginok Island\" by Lieutenant Sarichev (1826), and \"O[strov] Kigalga\"  or \"Kigalga Island\" by the Russian Hydrographic Department (1847) (Orth, 1971)."},{"VolcanoId":"ak229","Vnum":311280,"Volcano":"Recheshnoi","OfficialName":"Mount Recheshnoi","ParentVolcanoId":"ak229","ParentVolcano":"Recheshnoi","AgeClass":"Holocene","AgeSource":"Recheshnoi's west vent has a 3000 year old lava flow.","Composition":"mafic","IsMonitored":false,"VolcanoType":"Stratovolcano","NvewsThreat":"Moderate Threat","Description":"   From Wood and Kienle (1990): \"Mount Recheshnoi is a large, heavily glaciated stratovolcano on central Umnak Island, 10 km east of Mount Vsevidof, its nearest volcanic neighbor.  The central part of the cone is built on a flat erosional surface ~60 m above sea level cut on Tertiary plutonic and sedimentary rocks.  The east and northeast flanks overlie ~300 m of lava flows from older volcanoes.  The central 40-50 square km (above 1000 m elevation) consists of pyroclastic beds and a vent complex.  This area has been heavily eroded by 9 small valley glaciers and retains none of its original constructional volcanic form.  The summit area consists of a 4-km-long east-west ridge which may reflect construction from an older eastern vent and a younger western vent.  Below 1,000 m the volcano consists of andesite flows with minor pyroclastic interbeds.  The original construction is preserved in some upland areas between glaciers, especially on the western flank.  The central cone is probably mostly Pleistocene in age.  A glaciated basaltic parasitic cone exists on the northwest flank.  Post-glacial deposits are limited to andesitic cinder cones and flows on the east and west flanks, a series of small rhyolite domes on the west flank and a quartz-olivine andesite dome on the east-northeast flank.  There is a large zone of hot springs and a few geysers 8 km northeast of the summit.\"","NameOrigin":"\"Mount Recheshnoi\" is a Russian name, published by Coats in 1950 (Orth,1971). There have been many spelling variants of this name."},{"VolcanoId":"ak206","Vnum":311290,"Volcano":"Okmok","OfficialName":"Mount Okmok","ParentVolcanoId":"ak206","ParentVolcano":"Okmok","AgeClass":"Historical","AgeSource":"Okmok has had historical eruptions from at least three vents: Cone A, Cone B, and the new cone formed in 2008.","Composition":"basalt","IsMonitored":true,"VolcanoType":"Central shield complex with nested caldera","NvewsThreat":"High Threat","Description":"   From Miller and others (1998): \"Okmok Volcano occupies most of northeastern Umnak Island.  The volcano, built on a base of Tertiary volcanic rocks, consists of three rock series: older flows and pyroclastic beds of a pre-caldera shield complex; pyroclastic deposits of two major caldera-forming eruptions; and a post-caldera field of small cones and lava flows that includes historically active vents within the caldera (Byers, 1959).\r\n   \"Construction of the pre-caldera volcano began in late Tertiary or early Quaternary time.  Two whole-rock K-Ar analyses of a sample of basaltic lava are 1.7 and 2.1 +/- .2 m.y. (Bingham and Stone, 1973).  Basaltic flows and pyroclastics compose most of the older rocks (unit Qbm); flows are more voluminous than pyroclastic deposits (see Byers, 1959, plate 41).  Vent agglomerate is exposed in the walls of the younger caldera and tuffs and tuff-breccias occur further down the flanks.  Flows and pyroclastic beds dip radially from the caldera at less than 5 degrees in most sectors, except for local steepening and reversal of dips at former vents.  Such radial dips suggest that the older complex was a central volcano with parasitic vents.  Domes and plugs of andesite and rhyolitic composition and basaltic lava flows (Byers, 1959, p. 312) mark minor vents that were active before caldera formation; these rocks are only slightly modified by erosion and are presumably early post-glacial in age.\r\n   \"Catastrophic pyroclastic eruptions resulted in the formation of 2 overlapping calderas (Byers, 1959, p. 274).  The deposits, referred to as the Okmok Volcanics (Byers, 1959, p. 314), are mainly thick, non-sorted agglomerate at the caldera rim overlain by ash-flow tuffs, and airfall ash and pumice that cover the flanks of the volcano to the shoreline (unit Qov).  Two arcuate ridges located about 1.5 km north and east of the main topographic basin are the remnants of the older caldera, which formed about 8200 years ago (Black, 1975).  The topographic basin of the younger caldera is about 9.5 km in diameter; the maximum elevation of the rim is about 1070 m and the mean elevation of the floor, exclusive of areas underlain by post-caldera volcanic rocks, is about 370 m.  The occurrence of 2 major ash-flow sheets, separated by a basalt flow and erosional unconformity, supports the two caldera-forming eruptions (Miller and Smith, 1975).  Miller and Smith (1987) have reported a maximum C14 age of 2400 +/- 200 yr for the second and  younger caldera-forming eruption.\r\n   \"Numerous small flows, plugs, and cinder cones on the flanks of Okmok Volcano are interbedded with or overlie the upper pars of the Okmok Volcanics (unit Qyv).  Within the caldera, the oldest post-caldera deposits are brecciated pillow lavas and pyroclastic rocks that were deposited in a caldera lake.  The lake attained a maximum depth of about 150 m and the upper surface reached an elevation of about 475 m, at which point it overtopped the low point of the caldera rim.  A small shallow lake located near the outlet of the caldera is all that remains today.  Three dissected tuff cones may have been produced by eruptions beneath the former caldera lake.  Other cinder cones occur atop pillow lavas; such cones apparently breached the surface of the former lake.  Cinder cones and associated lava flows that are younger than the caldera lake are identified by structures and textures characteristic of subaerial eruption.  The documented eruption of 1945 occurred at a cinder cone near the southwest caldera wall (Byers, 1959; Robinson, 1948); this cone may have been the site of all historical activity of Okmok volcano.  Hot springs and fumaroles occur both within Okmok caldera and at Hot Springs cove, 20 km to the southwest.\"","NameOrigin":"Delanora Grey (2003) offers some insights into the name history of Mount Okmok: 'In Bergsland's (1994) Aleut Dictionary, the name Umnak (\"Unmax\") is said to perhaps be a derivative of \"una\", meaning \"out there on the sea.\"  Alternatively, Orth (1967), who got much of his information from Geoghegan (1944), reports that the name comes from \"umnaqs\" meaning \"fish line.\"  The origin of the name Okmok is unknown; it was called Unmagim Anatuu by the natives, meaning \"the stout one of Umnak\" (Bergsland, 1994).  Tulik Volcano was called \"Ismax\" according to Bergsland, but Orth says the Aleut name \"Tuliq\" was reported by the U.S.Army Corps of Engineers in 1942 and means \"crack or fissure.\"  It is interesting to note that the name Tanak (\"Tanaxsiqax\", as in Cape Tanak) translates as \"made into land\" (Bergsland, 1994), as the shoreline along the cape was extended outward by approximately 2 km during the first outburst flood from the caldera between 1560 and 1010 BP (Wolfe and Beget, 2002).  The author prefers this interpretation to Orth's (1967) report that the cape was named from the Unangam Tunuu \"tanaq\" meaning \"lace.\"'"},{"VolcanoId":"ak29","Vnum":311300,"Volcano":"Bogoslof","OfficialName":"Bogoslof Island","ParentVolcanoId":"ak29","ParentVolcano":"Bogoslof","AgeClass":"Historical","AgeSource":"Historical eruptions.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Stratovolcano","NvewsThreat":"Moderate Threat","Description":"   From Miller and others (1998): \"Bogoslof Island is the largest of a cluster of small, low lying islands that comprise the emergent summit of a large submarine stratovolcano that rises more than 1500 m above the Bering Sea floor (Byers, 1959, plate 39).  The volcano appears to be a back-arc feature as it occurs well behind the volcanic front of the main Aleutian arc.  The island has undergone dramatic changes in size and shape during historical time, an evolution that has been unusually well observed and recorded for such an isolated volcano.\r\n   \"The island is presently shaped like an irregular isosceles triangle about 2.0 km long and 0.75 km wide covering an area of 0.75 square kilometers.  Castle Rock, a steep, twin-spired pinnacle along the southwest side of the island is the eroded remnant of a dome extruded in 1796.  Vent agglomerate produced during the explosive phase of that eruption lies in fault contact with the dome material and is best exposed in the southeast part of the sea cliff below Castle Rock.\r\n   \"A blanket of basaltic agglomerate and ash is plastered against the steep north and east flanks of Castle Rock and extends north and east as a broad terrace.  This material is interpreted by Byers (1959) to have been deposited primarily during the 1926 eruption but may also be from earlier Bogoslof eruptions.  The tephra layer, along with a basaltic dome extruded in early 1927, comprises most of the area of the island, which is steadily being reduced by marine erosion.  The 1927 dome is a rounded knob more than 40 m high and 305 m in diameter on the northwest coast, and fronts an arcuate salt water lagoon to the east.  Cobble-boulder beaches fringe the island's north and southeast shores and a sand beach extends along the eastern margin.\r\n   \"About 610 m northwest of Bogoslof lies Fire Island, a tiny flat-topped stack resembling a lighthouse.  The island is the remnant of a dome extruded in 1883.  Domes produced during other episodes of Bogoslof volcanism have been completely destroyed through subsequent explosive eruption and marine erosion.\"","NameOrigin":"Quote from Orth (1971): \"Bogoslof Island\" is a Russian name meaning \"theologian,\" given because the island \"rose from the sea May 18, 1796, St. John's Day\" (Baker, 1906). The name \"O[strov] Ioanna Bogoslova,\" or \"John the Theologian's Island,\" was published by Lt. Sarichev (1826). Captain Tebenkov (1852) published the name \"O[strov] Bogoslova\" or \"theologian's island\"."},{"VolcanoId":"ak188","Vnum":311310,"Volcano":"Makushin","OfficialName":"Makushin Volcano","ParentVolcanoId":"ak188","ParentVolcano":"Makushin","AgeClass":"Historical","AgeSource":"Historical eruptions from summit.","Composition":"mafic","IsMonitored":true,"VolcanoType":"Stratovolcano with caldera and parasitic cone","NvewsThreat":"Very High Threat","Description":"   From Miller and others (1998): \"Makushin volcano is a broad, truncated stratovolcano, 1800 m high and 16 km in basal diameter, which occupies most of the triangular northwest extension of Unalaska Island.  A breached summit caldera, about 3 km across, contains a small cinder cone, eroded remnants of other cones, and several fumaroles.  The volcano is capped by an icefield of about 40 square km; subsidiary glaciers descend the larger flanking valleys to elevations as low as 305 m.\r\n   \"Makushin volcano was constructed during two periods of volcanism separated by an interval of pronounced erosion (Drewes and others, 1961).  Bedrock is exposed as high as 975 m on the southeast flank of the volcano.  The first episode began in Pliocene or early Pleistocene time (the oldest known age of lavas is 0.93 Ma [Nye, 1990]) and produced extensive flows and subordinate pyroclastic deposits of basaltic and andesitic composition, which enlarged the island by several kilometers along the northwest coast.  Radial dips of flows suggest that Makushin Volcano itself was the principal vent area.  The older flows are extensively glaciated, which implies a minimum age of late Pleistocene.  The summit of Makushin subsequently collapsed, forming a caldera.  Andesitic pyroclastic-flow and debris flow deposits occur in glaciated valleys on the north and south sides of the volcano indicating a Holocene age for the caldera-forming eruption (Miller and Smith, 1987).  Reeder (1983) reported a C14 age determination of 7950 +/- 90 ypb on organic soil directly beneath the pyroclastic flow deposits and Nye and others (1984) report a limiting C14 age of 4280 +/- 280 ybp on organic material in a debris flow.\r\n   \"Several monogenetic satellite vents composed of basaltic and andesitic lava flows, ash, and scoria cones occur within the summit caldera.  These vents also form smaller cones on Makushin's flanks and surrounding area.  Most of these vents have been slightly glaciated but blanket late Pleistocene topography indicating a latest Pleistocene or early Holocene age.  Pakushin cone, a multiple-cratered composite cone, lies 8 km southwest of Makushin Volcano.  Tabletop Mountain, the eroded remains of a pyroclastic cone encircled by flows originating from small flank vents, is 20 km northeast.  Wide Bay cone,  a small symmetric cone with an oval summit crater, occupies the northwest edge of Unalaska Bay, and Sugarloaf cone, built of steeply dipping, crudely bedded pyroclastics, is situated 14 km to the southwest.  The Point Kadin vents, 10 small cones and explosion craters aligned along a rift zone trending N75W from the summit caldera, lie just south of an ash-flow deposit which fills a valley extending north from the volcano to the coast.  The deposit is relatively undissected and may correlate with a blanket of airfall ash and cinders that covers part of the icefield on the volcano's northern flank.  Based on geomorphic analysis, Arce (1983) infers that the sequence of Holocene events to have been as follows: construction of Sugarloaf cone, activity at Tabletop Mountain, construction of Makushin cone, and lastly, construction of the Wide Bay cone and activity on the Pt. Kadin vents.\r\n   \"Arce (1983) concludes that at least 15 tephra layers of Holocene age are recognizable on northern Unalaska Island; however, he assigns some to satellite vents of Makushin Volcano and others to more distant sources, so the exact number of deposits attributable to Makushin Volcano is uncertain.\"","NameOrigin":"\"Makushin Volcano\" is a Russian name, probably derived from \"makushka,\" meaning \"the crown (of the head)\" or \"top,\" and applied to this feature because it is the highest point on Unalaska Island. Sarichev called this volcano \"Ognedyashushchaya Gora,\" meaning \"burning mountain\", and also \"Ayyagyh.\" Reverend Coxe (1787) wrote \"there is a burning mountain here called 'Ayagish.'\" (Orth, 1971)."},{"VolcanoId":"ak100","Vnum":311350,"Volcano":"Fisher","OfficialName":"Fisher Caldera","ParentVolcanoId":"ak100","ParentVolcano":"Fisher","AgeClass":"SuspHist","AgeSource":"Historical eruption - see Mount Finch. CFE was 9400 years ago.","Composition":"mixed","IsMonitored":true,"VolcanoType":"Caldera with post-caldera domes, lava and pyroclastic flows","NvewsThreat":"High Threat","Description":"   From Miller and others (1998): \"Fisher caldera is 11 km wide by 18 km long, and has a maximum internal relief of 929 m.  It is one of at least three volcanoes on Unimak Island that have been active in historical time.\r\n   \"The caldera is remarkable in size - one of the largest calderas in the Aleutian arc - and for the mobility of the ash flows that resulted from the caldera-forming eruption about 9100 years ago (Miller and Smith, 1977; 1987).  The ash flows reached the Pacific Ocean 8 km to the southeast, and swept part way up the slopes of stratovolcanoes to the east and southwest.  To the north, ash flows crossed 15 km of lowland to reach the Tugamak Range, surmounted drainage divides as much as 400 m above the lowland surface in the range, and continued northward an additional 8 km to the Bering Sea coastline.  Miller and Smith (1977) inferred that the ash flows had unusually high velocities to cross such topographic barriers and suggested that the high velocities resulted by ash fall-back from a high eruption column.\r\n   \"Fisher caldera was the location of a large andesitic stratovolcano that was largely destroyed during caldera formation.  Very little study has been done on the caldera itself.  Post-caldera activity of Fisher caldera appears to consist of dome emplacement and eruption of lava flows and associated pyroclastic material, some of which may be historical in age (Miller and Smith, 1977).\"","NameOrigin":"Fisher Caldera was named for Bernard Fisher of the U.S. Geological Survey, who lost his life in Umnak Pass while investigating the volcanic geology of the Aleutian Islands (U.S. Geographic Names Informaion System, accessed January 14, 2009."},{"VolcanoId":"ak252","Vnum":311360,"Volcano":"Shishaldin","OfficialName":"Shishaldin Volcano","ParentVolcanoId":"ak252","ParentVolcano":"Shishaldin","AgeClass":"Historical","AgeSource":"Historical eruptions.","Composition":"basalt","IsMonitored":true,"VolcanoType":"Stratovolcano","NvewsThreat":"High Threat","Description":"   From Miller and others (1998): \"Shishaldin Volcano, located near the center of Unimak Island, is a spectacular symmetrical cone about 16 km in diameter at the base.  The mountain, which rises to a summit 2857 m above sea level, is the highest peak in the Aleutian Islands and has a small summit crater from which a steady cloud of steam is emitted.  The upper 2000 m is almost entirely covered by perennial snow and ice.  It is flanked to the northwest by 24 monogenetic parasitic cones (Fournelle, 1988).  The Shishaldin cone is less than 10,000 year old and is constructed on a glacially eroded remnant of an ancestral soma and shield (Fournelle, 1988), which in turn are underlain by volcaniclastic rocks of probable late Tertiary age (McLean and others, 1978).  Fournelle (1988) suggests that the basement may consist, at least in part, of plutonic rocks.\"","NameOrigin":"Tebenkov (1852) named this volcano \"So[pka] Shishaldinskaya,\" which was later transliterated to \"Shishaldin Volcano.\" G.A. Sarichev reported its Unangam Tunuu name as \"Agajedan (Grewingk, 1850). Wagner (1937) wrote that it was named Volcan de Fernandez, by Martinez (Orth, 1971)."},{"VolcanoId":"ak135","Vnum":311370,"Volcano":"Isanotski","OfficialName":"Isanotski Peaks","ParentVolcanoId":"ak135","ParentVolcano":"Isanotski","AgeClass":"Pleistocene","AgeSource":"According to Nye (personal commun., 2004), Isanotski's features show signs of glaciation and Holocene-appearing features are absent.","Composition":"unknown","IsMonitored":true,"VolcanoType":"Stratovolcano","NvewsThreat":null,"Description":"   From Miller and others (1998): \"Isanotski volcano, located near the eastern end of Unimak Island, is a dissected, snow- and ice-covered stratovolcano with a basal diameter of about 10 km.  It is much more deeply eroded than neighboring Shishaldin volcano and lies between Shishaldin and Roundtop along a roughly east-west alignment.\"","NameOrigin":"\"Isanotski Peaks\" was derived from Isanotski Strait, and published by Captain Tebenkov as \"Sop[ka] Isanotskaya\" meaning \"Isanotski Volcano\". Isanotski is an Unangam Tunuu name reported by Captain Lutke (1836) as \"Issanakh\" from the word \"isanaq\" which, according to R.H. Geoghegan, means \"tear (split or strait)\" (Orth, 1971). Bergsland (1994) reports the Unangam Tunuu placename as \"Iisan.\""},{"VolcanoId":"ak236","Vnum":311380,"Volcano":"Roundtop","OfficialName":"Roundtop Mountain","ParentVolcanoId":"ak236","ParentVolcano":"Roundtop","AgeClass":"Holocene","AgeSource":"Roundtop had an eruption dating to 9100-10,000 14C yr BP (Carson and others, 2002).","Composition":"unknown","IsMonitored":false,"VolcanoType":"Stratovolcano","NvewsThreat":"Moderate Threat","Description":"   From Wood and Kienle (1990): \"Roundtop is an eroded and glaciated stratovolcano, located ~13 km southwest of the village of False Pass.  In the 1930's warm springs were found on its slopes.  Recent field study indicates the presence of Holocene pyroclastic flows and a group of domes south of Roundtop, as well as a thick silicic pre-Holocene flow.\"","NameOrigin":"This feature was reported as \"Round Top\" by the U.S. Coast and Geodetic Survey in 1902, and called \"Dome\" by J.F. Moser, U.S. Navy, in 1897 (Orth, 1971)."},{"VolcanoId":"ak8","Vnum":311390,"Volcano":"Amak","OfficialName":"Amak Island","ParentVolcanoId":"ak8","ParentVolcano":"Amak","AgeClass":"SuspHist","AgeSource":"Possible historical eruptions (Marsh, in Wood and Kienle, 1990).","Composition":"andesite","IsMonitored":false,"VolcanoType":"Stratovolcano","NvewsThreat":"Low Threat","Description":"   From Wood and Kienle (1990): \"Amak is a small (~1 cubic km), young volcano in the Bering Sea some 50 km north of Frosty Peak volcano at Cold Bay at the western tip of the Alaska Peninsula.  It is unusual in its position, which is significantly north of the main Aleutian volcanic front; Bogoslof, some 250 km west, is the only other such Aleutian volcano.  In overall character, Amak is much like a large volcanic dome except that it has a well-formed crater from which granular, blocky leveed flows have erupted in historic times.  The earlier volcanism, perhaps some 4,000-5,000 yr ago, consisted mostly of thin (~3 m) platy to massive andesite.  U-shaped valleys in the older series of flows indicate significant glaciation during the latest ice phase some 6,700 yr BP.  The southern margin of Amak is a grassy, apparently wave-cut alluvial plain, which contains a flat-bottomed crater with a distinct upturned rim, which may be a maar.  Amak lavas are similar in overall composition to those of the Cold Bay volcanic center except in a small but significant higher concentration of potash in Amak rocks.\"","NameOrigin":"\"Amak volcano\" is an informal name applied to the peak on Amak Island.  \"Amak Island\" is an Unangam Tunuu name published as \"O[strov] Amak\" or \"Amak Island,\" by Captain Tebenkov (1852) and Amax by Bergslund (1994)."},{"VolcanoId":"ak108","Vnum":null,"Volcano":"Gilbert","OfficialName":"Mount Gilbert","ParentVolcanoId":"ak108","ParentVolcano":"Gilbert","AgeClass":"SuspHolo","AgeSource":null,"Composition":"unknown","IsMonitored":false,"VolcanoType":"Stratovolcano?","NvewsThreat":null,"Description":"   From Wood and Kienle (1990): \"Mount Gilbert is a small extinct volcano on northernmost Akun Island.  Its northern flank is steep and heavily eroded, presumably by the sea, while its southern flank is little dissected.  The summit region has been completely eroded and was presumably north of, and higher than, the present summit.  A 20,000 square m zone of slightly older fumarolically altered rock exists 1.5 km northeast of the current summit.  Prior to 1948, active fumaroles in this area produced steam plumes visible from a distance; fumarolic activity has since stopped.  The altered ground was the site of an unsuccessful attempt to mine sulfur in the 1920's.\"","NameOrigin":"Mount Gilbert's name was published in the 1947 Coast Pilot. It is possible that this volcano was named for John J. Gilbert, U.S. Coast and Geodetic Survey, commander of the steamer Pathfinder during 1900-01 (Orth, 1971)."},{"VolcanoId":"ak105","Vnum":312010,"Volcano":"Frosty","OfficialName":"Frosty Peak","ParentVolcanoId":"ak105","ParentVolcano":"Frosty","AgeClass":"SuspHolo","AgeSource":"Wilson and Forbes (2001) believe Frosty is a Holocene feature.","Composition":"andesite","IsMonitored":false,"VolcanoType":"Stratovolcanoes","NvewsThreat":"Moderate Threat","Description":"   From Smithsonian Institution, online database, accessed December 8, 2003: \"Frosty volcano, the youngest of two large volcanic structures of the Cold Bay volcanic complex, is the westernmost Holocene volcano of the Alaska Peninsula. The oldest products of the roughly 100 cu km Cold Bay complex, which lies SW of the village of Cold Bay, form the glacially dissected late-Pliocene to early Pleistocene Morzhovoi Volcanics at the southern end of the complex. Frosty Peak to the north is a symmetrical late-Pleistocene to Recent stratovolcano constructed within the southernmost of two coalescing craters. The western wall of the ice-filled northern crater is breached by a large valley glacier. The symmetrical summit cone rises about 600 m above the floor of the southern crater.\"","NameOrigin":"Frosty Peak was named by W.H. Dall of the U.S. Coast and Geodetic Survey, in 1882 (Orth, 1971)."},{"VolcanoId":"ak210","Vnum":312030,"Volcano":"Pavlof","OfficialName":"Pavlof Volcano","ParentVolcanoId":"ak210","ParentVolcano":"Pavlof","AgeClass":"Historical","AgeSource":"Historical eruptions.","Composition":"basaltic_andesite","IsMonitored":true,"VolcanoType":"Stratovolcano","NvewsThreat":"High Threat","Description":"   From Miller and others (1998): \"Pavlof Volcano is a largely snow-covered, cone-shaped mountain with a high ridge extending to the southwest towards the rim of Emmons Lake Caldera.  The volcano is approximately 7 km in diameter and has active vents on the north and east sides close to the summit (McNutt and others, 1991).  It is situated high on the northeastern flank of Emmons Lake Caldera along a northeast-trending alignment of vents that includes Pavlof Sister, and several intracaldera cones (Kennedy and Waldron, 1955).  The stratovolcano is relatively undissected and is mostly Holocene in age.  Pavlof lies within the Shumagin seismic gap (Davies and others, 1981).\"  The name Pavlof comes from Russian, translating to \"Paul\" or \"Saint Paul\".  This volcano name was first published as \"Pavlovskoi Volcan\" by Captain Lutke in 1836.","NameOrigin":"\"Pavlof Volcano\" is a Russian name, meaning \"Paul\" or \"Saint Paul,\" published as \"Pavlovskoi Volcan\" by Captain Lutke (1836), and as \"Pavlovskaya Sopka\" on a Russian Hydrographic Department Chart (1847) (Orth, 1971)."},{"VolcanoId":"ak301","Vnum":312070,"Volcano":"Veniaminof","OfficialName":"Mount Veniaminof","ParentVolcanoId":"ak301","ParentVolcano":"Veniaminof","AgeClass":"Historical","AgeSource":"Historical eruptions.","Composition":"mafic","IsMonitored":true,"VolcanoType":"Stratovolcano with a summit caldera","NvewsThreat":"High Threat","Description":"   From Miller and others (1998): \"Mount Veniaminof is a broad central mountain, 35 km wide at the base, truncated by a spectacular steep-walled summit caldera 8x11 km in diameter.  The caldera is filled by an ice field that ranges in elevation from approximately 1750 to 2000 m; ice obscures the south rim of the caldera and covers 220 square km of the south flank of the volcano.  Alpine glaciers descend from the caldera through gaps on the west and north sides of the rim and other alpine glaciers occupy valleys on the north-, east-, and west-facing slopes of the mountain.  In the western part of the caldera, an active intracaldera cone with a small summit crater has an elevation of 2156 m, approximately 330 m above the surrounding ice field.  The rim of a larger but more subdued intracaldera cone protrudes just above the ice surface in the northern part of the caldera; based on limited exposure and physiographic features, it may have a summit crater as much as 2.5 km in diameter.\r\n   \"Andesitic and dacitic ash-flow tuffs from the caldera-forming eruption occur in many of the valleys on the north slope of the volcano and are found as far away as 50 km from the caldera rim on both the Bering Sea and Pacific Ocean coasts.\r\n   \"A northwest-trending belt of post-caldera cinder and scoria cones, including the two intracaldera cones, extends from near the Bering Sea coast approximately 55 km across the main volcanic edifice and the Aleutian Range divide, well down the Pacific slope (Detterman and others, 1981).\"","NameOrigin":"Constantin Grewingk in 1849 wrote \"We have named this point on our maps 'Vukan Wenjaminow'.\"  Named in honor on Father Ioann [Ivan Popov] Veniaminov, 1797-1879, Russian Orthodox priest, Bishop of Russian America, and Metropolitan of Moscow, whose writings on Unangam Tunuu language and ethnology are still standard references (Orth, 1971)."},{"VolcanoId":"ak25","Vnum":312080,"Volcano":"Black Peak","OfficialName":"Black Peak","ParentVolcanoId":"ak25","ParentVolcano":"Black Peak","AgeClass":"Holocene","AgeSource":"Adleman (2005) reports Neal and McGimsey 14C dates of 500 14C yBP to 4,600 14 C yBP.","Composition":"andesite","IsMonitored":false,"VolcanoType":"Stratovolcano and lava domes","NvewsThreat":"Moderate Threat","Description":"   From Wood and Kienle (1990): \"Black Peak is a deeply eroded, highly altered stratovolcano/dome complex with a small caldera at its eastern edge.  The caldera is ice-free and contains two small lakes; most of the interior of the caldera is occupied by a complex of nested dacitic domes.  The volcano rests on a north-dipping basement of Pliocene volcanogenic non-marine sedimentary rocks.\r\n   \"The flows, domes, and volcaniclastic rocks that make up the pre-caldera cone range in composition from andesite to dacite.  Dacitic ash-flow tuffs and coarse block-and-ash flows fill the Bluff and Ash Creek valleys to as much as 100 m on the north and west sides of the volcano.   The pyroclastic flows that deposited these tuffs had limited distribution and appear to have been relatively sluggish; they also appear to have had a large air-fall component, judging from the crude stratification in the ash-flow tuff.  In spite of the caldera's small diameter, the widespread climactic air fall and the thickness of the ash-flow tuffs suggest a bulk eruption volume of \u003e10 cubic km.\"","NameOrigin":"The name \"Black Peak\" is a translation of the Russian name \"So[pka] Chornaia,\" published by Captain Tebenkov in 1852 (Orth, 1971)."},{"VolcanoId":"ak49","Vnum":312110,"Volcano":"Chiginagak","OfficialName":"Mount Chiginagak","ParentVolcanoId":"ak49","ParentVolcano":"Chiginagak","AgeClass":"SuspHist","AgeSource":"Possible historical eruptions.","Composition":"mixed","IsMonitored":false,"VolcanoType":"Stratovolcano with domes","NvewsThreat":"Moderate Threat","Description":"   From Miller and others (1998): \"Chiginagak volcano is a symmetric composite cone about 8 km in diameter built on late Tertiary volcanic rocks and Jurassic-Cretaceous sedimentary rocks and located on a southwest trending regional anticline (Detterman and others, 1983).  A deep breach on the south flank on the volcano extends to a small summit crater and exposes widespread alteration of interbedded lava flows and breccias near the summit of the volcano.  Snow and ice cover much of the uppermost 1000 m of the cone.\r\n   \"Monolithologic breccias (vb) low on the west side of the volcano represent at least two early periods of dome growth and collapse, separated by a period of lava extrusion.  The undissected form of the cone is the result of the eruption of andesitic lava flows and pyroclastic rocks (vu) following the emplacement of the youngest breccias.  Somewhat younger andesite and dacite flows occur on the west flank and basalt flows (some as young as Holocene) occur on the eastern flank of the volcano.  Satellitic dacite (?) domes of Holocene age occur high on the east and west flanks, the most recently active of which is the eastern dome which was the source of thin pyroclastic or epiclastic deposits (ba) that overlie nonglaciated basaltic lava flows.\"","NameOrigin":"Mount Chiginagak's name was first published in 1888 by the U.S. Bureau of Fisheries (Orth, 1971)."},{"VolcanoId":"ak295","Vnum":312130,"Volcano":"Ugashik-Peulik","OfficialName":null,"ParentVolcanoId":"ak295","ParentVolcano":"Ugashik-Peulik","AgeClass":"SuspHist","AgeSource":"Possible historical eruptions from Mount Peulik.","Composition":"mixed","IsMonitored":true,"VolcanoType":"Stratovolcano with summit and flank domes, overlapping Ugashik caldera","NvewsThreat":"High Threat","Description":"   From Miller and others (1998): \"Mount Peulik volcano, a small truncated stratovolcano with a basal diameter of about 10 km, is located just north of the main axis of the Aleutian Range near Becharof Lake on the Alaska Peninsula.  The volcano lies west of the axis of a northeast-striking syncline (Detterman and others, 1987) and is built upon Jurassic sedimentary rocks.  The volcano partially overlaps the north flank of Ugashik caldera, a small circular structure about 5 km in diameter and of probable late Pleistocene age.  A summit crater, about 1.5 km in diameter, has been breached on the west side and is occupied by a dome about 0.5 km in diameter.  This dome, and possibly earlier predecessors, were the source the a thick deposit of block-and-ash flows that underlie about 40 square km of the western flank of the volcano.  A smaller dome occurs on the east flank at an elevation of 1200 m and was the source of a small block-and-ash flow.  Avalanche deposits representing an earlier sector collapse (Miller, unpublished data) underlie an area of 75 square km northwest of the volcano.  Flows from flank eruptions of Peulik cover about 8 square km north of the volcano extending as far as Becharof Lake.\"","NameOrigin":"\"Ugashik-Peulik volcanic center\" is an informal name. The principal peaks in the center are Mount Peulik and Mount Ugashik."},{"VolcanoId":"ak112","Vnum":312190,"Volcano":"Griggs","OfficialName":"Mount Griggs","ParentVolcanoId":"ak112","ParentVolcano":"Griggs","AgeClass":"Holocene","AgeSource":"Fierstein (2007) shows that Griggs had an explosive eruption as recently as less than 3,460 14C yBP.","Composition":"andesite","IsMonitored":true,"VolcanoType":"Stratovolcano","NvewsThreat":"High Threat","Description":"   From Wood and Kienle (1990): \"A spectacular, little-dissected cone, Mount Griggs towers 1,700 m above the north margin of the Valley of Ten Thousand Smokes, its summit only 10 km north of Novarupta.  Uniquely among the stratovolcanoes of the Katmai district, it lies 10 km behind (northwest of) the remarkably linear (N66E-trending) volcanic front defined by Martin, Mageik, Trident, Katmai, and Snowy Mountain centers.\r\n   \"Griggs's truncated summit is an expression of 3 concentric craters, the outermost of which is 1.5 km wide, breached to the southwest, and filled by a semi-annulus of ice wrapped around a young central cone containing the nested inner craters.  The main outer crater probably originated by early Holocene collapse, and formation of a 1-cubic km-scale debris avalanche, remnants of which survive on the lower west-southwest flank and across the valley on Broken Mountain.  Much of the amphitheater was subsequently filled by the nested inner cone.  Outer slopes of the main and inner cones expose a few scoria flows and local scoria falls but principally consist of complexes of the thin brecciated lava tongues, overlapping and bifurcating in the manner so characteristic of summit-fed andesites on steep slopes.  The total volume of Mount Griggs is ~25 cubic km.\r\n   \"Griggs's products are chiefly olivine-pyroxene andesites; 27 samples range continuously from 54.5 to 63.5% SiO2.  They are consistently more potassic than products of the other Katmai cluster volcanoes, their K2O contents being 1.3-1.4% at 57.5% SiO2 and 1.7-1.9% at 60%.  Isotopic data also suggest a source mixture and plumbing system independent of the other nearby centers.\r\n   \"Numerous SO2-rich fumarolic jets occur between 1,940-m and 2,180-m elevation atop the inner cone and along a steep chute on its upper southwest slope.  Orifice temperatures (measured by Dave Johnston in 1978-9) range from 96 degrees to 108 degrees C, and their condensates have pH ~1.  Each orifice is constructing its own mound of sulfur sublimate.  Downhill fumaroles are hottest and loudest, their roar commonly audible from the valley floor.\"","NameOrigin":"Mount Griggs was named in 1956 by Gilbert Grosvenor, National Geographic Society, for Robert Fiske Griggs (1881-1952), botanist and leader of six National Geographic Society expeditions to the Katma District from 1915 to 1930. These expeditions lead to the 1918 creation of the Katmai National Monument. This volcano was previously called \"Knife Peak\" (Orth, 1971)."},{"VolcanoId":"ak257","Vnum":312200,"Volcano":"Snowy","OfficialName":"Snowy Mountain","ParentVolcanoId":"ak257","ParentVolcano":"Snowy","AgeClass":"Holocene","AgeSource":"Fierstein (2007) shows that Snowy's summit dome was emplaced less than 250 14C years BP, making it possibly historical.","Composition":"mafic","IsMonitored":true,"VolcanoType":"Lava domes","NvewsThreat":"High Threat","Description":"   From Hildreth and Fierstein, 2003: “Snowy Mountain is a small andesite-dacite volcanic center that straddles the rangecrest northeast of the main Katmai cluster, separated by about 10 km from Mount Griggs. Snowy Mountain was named during the National Geographic Society expedition to Katmai in 1917 (Griggs, 1922, p. 131). The name chosen evidently reflected how impressed those explorers were with its extensive mantle of snow and ice as seen from upper Katmai River, which was their closest approach to the edifice. Rising to an elevation of 7,090 ft (2,161 m), Snowy Mountain remains today the source of 10 substantial glaciers. Because glacial ice still covers nearly 90 percent of the edifice, the principal rock exposures are limited to narrow ice-bounded arêtes at higher elevations and ice-scoured lava-flow benches at lower elevations.\r\n   “Activity began at about 200 ka, and infrequent eruptions have since taken place from two vents 4 km apart that built contiguous subedifices which extensively overlap in age (Hildreth and others, 2001). Only the northeast vent has been active in the Holocene. Sector collapse of the hydrothermally weakened upper part of the northeast cone in the late Holocene produced a 22-square-km debris avalanche and left a 1.5-square-km amphitheater that was subsequently occupied by a blocky dacite lava dome. Many products of the southwest vent are olivine-bearing andesites (55-62 percent SiO2), whereas those of the northeast vent are largely pyroxene dacites (62-64 percent SiO2). Estimates of eruptive volume yield 8+/-2 cubic km for the northeastern edifice, 5 +/- 2 cubic km for the southwestern, and 13 +/- 4 cubic km for the Snowy Mountain center as a whole. Only half to two-thirds of this material remains in place on the glacially ravaged skeletal edifices today.\"\r\n   From Wood and Kienle, 1990: \"An active fumarole field on the summit of the tallest peak has melted holes through the ice.  A zone of active shallow-level seismicity beneath Snowy Mountain is probably a manifestation of a hydrothermal system.  This, together with its youthful, undissected form, suggests that volcanism at Snowy Mountain is recent.  But no historic activity has been reported.\"","NameOrigin":"\"Snowy Mountain\" was identified by R.F. Griggs in 1916 as \"Princess Peak\" and then, in 1919, as \"Snowy Mountain\", \"because of the extensive glaciers nearby\" (Orth, 1971)."},{"VolcanoId":"ak174","Vnum":312230,"Volcano":"Kukak","OfficialName":"Kukak Volcano","ParentVolcanoId":"ak174","ParentVolcano":"Kukak","AgeClass":"SuspPleist","AgeSource":"Although Kukak has active fumaroles, it's age of last eruption is unknown.","Composition":"unknown","IsMonitored":false,"VolcanoType":"Stratovolcano","NvewsThreat":"Moderate Threat","Description":"   From Smithsonian Institution, online database, accessed December 8, 2003: \"The almost completely ice-covered Kukak volcano lies west of Hallo Bay near the NE end of a glacier-mantled range extending from Mount Katmai. Kukak volcano contains a vigorous fumarole field at the southern base of the hydrothermally altered northern summit and is the only one of the Denison-Steller-Kukak chain of volcanoes to display geothermal activity. Two reports of historical eruptions at Kukak from Hantke (1959) appear to be erroneous. The report of a 1951 eruption is an apparent reference to a July 22, 1951 ashfall at Kukak Bay, which was attributed by Muller and others (1954) to Martin volcano. A 1953 explosive \"eruption\" was single large puff of steam followed by steaming from caverns in Hook Glacier (Muller and others 1954).\"","NameOrigin":"The U.S. Coast and Geodetic Survey reported the name \"Kugak Volcano\" for \"Kukak Volcano\" in 1908. The name was later officially changed to \"Kukak Volcano\" to agree with the name of nearby Kukak Bay (Orth, 1971)."},{"VolcanoId":"ak103","Vnum":312260,"Volcano":"Fourpeaked","OfficialName":"Fourpeaked Mountain","ParentVolcanoId":"ak103","ParentVolcano":"Fourpeaked","AgeClass":"Historical","AgeSource":"Historical eruption (2006 phreatic eruption.)","Composition":"andesite","IsMonitored":false,"VolcanoType":"Stratovolcano","NvewsThreat":"High Threat","Description":"   From Wood and Kienle (1990): \"Fourpeaked Mountain consists of small isolated volcanic exposures surrounded by the Fourpeaked Glacier.  The exposures are found along ridge crests and cliff faces on the sides of ridges that radiate out from the ice-covered summit.  Lava flows are interlayered with volcanic agglomerate in the isolated exposures.\r\n   \"Orientation of lava flows suggests the present summit of Fourpeaked is probably the vent for Fourpeaked volcano.  Extensive hydrothermal alteration of rocks in this area is consistent with this vent location.\r\n   \"Fourpeaked is known only from limited reconnaissance studies.  The lavas are porphyritic andesite.\"","NameOrigin":"\"Fourpeaked Mountain\" is a descriptive name, transladed from \"G[ora] Chetyrekglavaya\" by George Davidson, U.S. Coast and Geodetic Survey. \"Gora Chetyrekglavaya\" means \"four-headed mountain,\" and was published by Tebenkov in 1852. The Russian Hydrographic Department had previously published \"G[ora] Chetyrekh,\" meaning \"mountain of four heads\" in 1847. This may be a mountain called \"Saint Dolmat\" on a 1748 Russian manuscript map (Wagner, 1937; Orth, 1971)."},{"VolcanoId":"ak14","Vnum":312090,"Volcano":"Aniakchak","OfficialName":"Aniakchak Crater","ParentVolcanoId":"ak14","ParentVolcano":"Aniakchak","AgeClass":"Historical","AgeSource":"Historical eruption.","Composition":"unknown","IsMonitored":true,"VolcanoType":"Stratovolcano with summit caldera, intracaldera domes, cones, and vents","NvewsThreat":"High Threat","Description":"   From Miller and others (1998): \"Aniakchak Crater is an ice-free, circular caldera about 10 km in diameter and a maximum of 1 km deep which was first described by Smith (1925).  The pre-caldera cone was built upon a basement of Tertiary sedimentary and volcanic rocks and Jurassic-Cretaceous sedimentary rocks, which are exposed high on the east and south walls of the caldera (Detterman and others, 1981).  The elevation of the caldera rim varies from 1,341 m to 610 m.  Surprise Lake, a 3.2-km-long lake in the northeast part of the caldera at an elevation of about 335 m is the source of the Aniakchak River, which flows through a breach in the eastern wall of the caldera.  Numerous domes, flows, and cones occupy the interior of the caldera (Neal and others, 1992); the largest cone is Vent Mountain, 2.5 km in diameter and rising 430 m above the floor of the caldera.  The pre-caldera cone was built on the west side of a basement high.  The cone was deeply dissected by numerous glaciers that cut U-shaped valleys into the slopes before the caldera-forming eruption.\r\n   \"Ash flows from the caldera-forming eruption - 3430 +/- 10 yrs B.P. (Miller and Smith, 1987) - reached both the Bering Sea and the Pacific Ocean (Miller and Smith, 1977).  They are typically non-welded and fill glacial valleys to a depth of at least 75 m adjacent to the caldera rim.  The ash flows were highly mobile, over-running 260-meter-high passes in the Aleutian Range and traveling as far as 50 km from the caldera rim (Miller and Smith, 1977).\"","NameOrigin":"Sargent and Smith (1922) named Aniakchak Crater and Aniakchak peak. The name was probably derived from nearby Aniakchak Bay (Orth, 1971)."},{"VolcanoId":"ak280","Vnum":311080,"Volcano":"Tanaga","OfficialName":"Tanaga Volcano","ParentVolcanoId":"ak280","ParentVolcano":"Tanaga","AgeClass":"Historical","AgeSource":"Historical eruptions.","Composition":"mixed","IsMonitored":true,"VolcanoType":"Stratovolcano with two flanking stratovolcanoes","NvewsThreat":"Moderate Threat","Description":"   Tanaga Island lies in the Andreanof Islands approximately 100 km (62 miles) west of the community of Adak and 2025 km (1260 miles) SW of Anchorage. The northern half of the island is home to the Tanaga volcanic complex, comprising three main volcanic edifices. Tanaga volcano is the tallest of these (1,806 m or 5,925 ft) and lies in the center of the complex.  The last known eruption of Tanaga occurred in 1914 and earlier eruptions were reported in 1763-1770, 1791, and 1829. Reports of these eruptions are vague, but deposits on the flanks of the volcano show that typical eruptions produce blocky lava flows and occasional ash clouds. Eruptions have occurred both from the summit vent and a 1,584 m (5,197 ft)-high satellite vent on the volcano's northeast flank. Immediately west of Tanaga volcano lies Sajaka, a 1,354 m (4,443 ft)-high compound edifice with an older cone to the east that collapsed into the sea within the last few thousand years, and a new cone that has grown in the breach. The new cone is 1,312 m (4,305 ft) high and consists of steeply dipping, interbedded cinders and thin, spatter-fed lava flows. To the east of Tanaga lies Takawangha, which is separated from the other active volcanic vents by a ridge of older rock. Takawangha's 1,449 m (4,754 ft)-high summit is mostly ice-covered, except for four young craters that have erupted ash and lava flows in the last few thousand years. Parts of Takawangha's edifice are hydrothermally altered and may be unstable, and could produce localized debris avalanches. No historical eruptions are known from Sajaka or Takawangha; however, field work shows that recent eruptions have occurred and it is possible that historic eruptions attributed only to Tanaga may instead have come from these other vents.","NameOrigin":"\"Tanaga Volcano\" was published in the 1944 Aleutian Coast Pilot (Orth, 1971)."},{"VolcanoId":"ak144","Vnum":311110,"Volcano":"Kanaga","OfficialName":"Kanaga Volcano","ParentVolcanoId":"ak144","ParentVolcano":"Kanaga","AgeClass":"Historical","AgeSource":"Historical eruptions.","Composition":"andesite","IsMonitored":true,"VolcanoType":"Stratovolcano within caldera","NvewsThreat":"High Threat","Description":"   From Miller and others (1998): \"Kanaga Volcano occupies the northern corner of Kanaga Island, one of the most southerly members of the Aleutian chain.  It is a symmetric composite cone 1307 m high and 4.8 km in diameter at sea level, built of interbedded basaltic and andesitic lava flows, scoria layers, and pyroclastic rocks.  Mudflow deposits and other volcaniclastic rocks occur on the volcano's lower slopes.  A circular summit crater, approximately 200 m across and 60 m deep, contains recent deposits of vent agglomerate, and several active fumaroles.\r\n   \"A mantle of volcanic ash and pumice, up to 7 m thick, and containing several soil horizons, blankets the northern half of the island.  Most of this deposit was probably erupted from Kanaga Volcano, although some may be derived from explosive eruptions on nearby islands (Coats, 1956, p. 74; Fraser and Barnett, 1959, p. 226).  A thin layer of andesitic and basaltic pumice, younger than the ash-and-pumice mantle, coats the volcano's upper slopes, and blocks of dense basalt occur across the island.  Fragments of the latter material have produced impact craters up to 4 km from the summit.  Four young andesitic flows extend from fissures near the summit of the cone on the south, southwest, and northeast flanks (unit Qkb).\r\n   \"Kanaga Volcano is flanked on the south and east by an arcuate ridge up to 800 m in elevation; a soma lake, 2 km in diameter, is situated between Kanaga Volcano and the southeast corner of the arcuate ridge.  The ridge and associated scarp may represent the eroded remnant of a caldera rim.  Two observations support the caldera origin of the ridge.  First, although dissected, remnants of the ridge are located along 150 degrees of an approximately circular arc and the radially outward dip of the comprising flows indicates a central source near the present summit of Kanaga Volcano.  Secondly, a thin (0.6-9 m)) but widespread blanket of andesitic crystal-lithic tuff (unit Qat) occurs over northern Kanaga Island south and east of Kanaga Volcano (Coats, 1956) where relative age and lithologic character suggest that it may be the product of a caldera-forming eruption.\r\n   \"Coats (1950, 1956) suggested the caldera formed through collapse of a Tertiary volcano (Mount Kanaton) near the end of Pleistocene time.  However, Miller and Kirianov (1994) suggested periods of caldera formation on Kanaga occurred ~6000, ~4,500, and ~3,000 yBP based on tephrachronology studies on nearby Adak Island.\r\n   \"Precaldera rocks include flows and pyroclastic rocks and minor intrusive rocks.  Coats (1956), and Fraser and Barnett (1959) have assigned a late Tertiary to Pleistocene age to these older rocks.  Apparently several episodes of volcanism preceded construction of modern Kanaga Volcano.  Low outward dips imply that most of the older rocks were part of a broad, shield-shaped volcano with a vent area near the site of Kanaga Volcano.  There is, however, some evidence that at least one composite cone was constructed on the site before formation of the caldera, and of other vent eruptions form the flanks of the ancient volcano (Coats, 1956).\r\n   \"Evidence of glaciation has not been noted on Kanaga Island, although adjacent islands such as Tanaga display signs of glacial erosion down to sea level.\"","NameOrigin":"Kanaga Volcano's name is derived from Kanaga Island. Kanaga Island is an Unangam Tunuu name published by Sarichev (1826) and Tebenkov (1852) as \"O[strov] Kanaga\" or \"Kanaga Island.\" Baker (1906) suggests that this may be the island called \"Kanaton\" by Captain James Cook in 1778 (Orth, 1971)."},{"VolcanoId":"ak34","Vnum":311010,"Volcano":"Buldir","OfficialName":"Buldir Volcano","ParentVolcanoId":"ak34","ParentVolcano":"Buldir","AgeClass":"SuspHolo","AgeSource":"Smith and Shaw (1975) suggest a Holocene age for Buldir, although Coats (1956) thought Pleistocene.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Stratovolcano cluster","NvewsThreat":"Low Threat","Description":"   From Wood and Kienle (1990): \"Buldir Island is the westernmost volcanic center of the present Pleistocene to Recent Aleutian volcanic front.  The next westward subaerial volcanism is in Kamchatka.  Buldir is a small (~2 cubic km), isolated, and mountainous island consisting of two volcanoes, the older of which is Buldir volcano and the younger East Cape volcano.  Although broadly of similar age, a significant lapse of time between their formation allowed considerable marine and subaerial erosion, the products of which fill the lowlands.  Buldir volcano, which once had a parasitic cone, consists of a few thin (3-m), olivine-bearing, high alumina basalt flows and much volcaniclastic debris.  East Cape volcano has two vents: the principal vent forms an eruptive cone cored by a late stage plug, whereas the secondary vent is a large flank dome of hornblende andesite.\r\n   \"Buldir Island is unusual in its restricted flora relative to neighboring islands, suggesting that it is comparatively young and not a fragment of a much older, larger subaerial island.  The once nearly extinct Aleutian goose (a lesser Canada goose) was rekindled from relict nestings on Buldir.\"","NameOrigin":"The name Buldir Volcano, on Buldir Island, was first reported by Coats (1953). Concerning the name of Buldir Island, however, the October 28, 1741 entry in the log book of the St. Peter, commanded by Vitus Bering, reads \"by the will of God Stephan Buldirev [later written as Stephan Bogdriev], naval cooper, died of scurvy\" (Golder, 1922). The same day Bering named an island \"St. Stephen.\" Many scholars, including Golder, correlate the island of Bering with that of present-day Buldir Island, and, if so, it may have been named for the sailor that died on its discovery day. The name \"Ostrov Buldir\" was published on a 1791 map by Lt. Sarichev, and thus he may be responsible for the naming (Orth, 1971)."},{"VolcanoId":"ak277","Vnum":311090,"Volcano":"Takawangha","OfficialName":null,"ParentVolcanoId":"ak277","ParentVolcano":"Takawangha","AgeClass":"SuspHolo","AgeSource":"Coombs and others (2007) report Takawangha active in the Holocene.","Composition":"mixed","IsMonitored":true,"VolcanoType":"Stratovolcano","NvewsThreat":"Moderate Threat","Description":"   From Smithsonian Institution, Global Volcanism Program online database, accessed December 8, 2003: \"Takawangha is a 1449-m-high, youthful volcano with an ice-filled caldera on northern Tanaga Island, near the western end of the Andreanof Islands. Takawangha lies across a saddle from historically active Tanaga volcano to the west; older, deeply eroded volcanoes lie adjacent to Takawangha on the east. Numerous small post-caldera tephra cones are located within the caldera and on its rim and flanks. The youngest cones are some of those inside the caldera of the basaltic-to-dacitic volcano. No historical eruptions are known from Takawangha.\"","NameOrigin":"Takawangha is an alternate name for Tanaga Island, and unofficially used to describe the youthful volcano on northern Tanaga Island, east from Tanaga Volcano."},{"VolcanoId":"ak28","Vnum":311100,"Volcano":"Bobrof","OfficialName":"Bobrof Volcano","ParentVolcanoId":"ak28","ParentVolcano":"Bobrof","AgeClass":"SuspHolo","AgeSource":"Smith and others (1987) considered Bobrof to be possibly Holocene in age.","Composition":"unknown","IsMonitored":false,"VolcanoType":"Stratovolcano","NvewsThreat":"Low Threat","Description":"   From Wood and Kienle (1990): \"Andesitic pyroclastic flows sampled at a seismic station (Adak network) are indicative of explosive eruptions; lavas at the same site indicate that more quiescent extrusive activity also occurred.  Texturally, the rocks resemble those of Moffet volcano 50 km to the east.  The geology of this small island and the timing of its volcanism are unknown.\"","NameOrigin":"Bobrof Volcano, comprising Bobrof Island, bears the name of the island. The name \"Bobrof Island\" was reported in 1790 by Commodore Joseph Billings. Captain Tebenkov (1852) published the name \"O[strov] Bobrovoy Vilga\" or \"Sea Otter Vilga Island.\" (Orth, 1971). Bergsland (1994) reports the Unangam Tunuu name of Bobrof Island as \"Walĝa\", meaning \"the one on this side (tribal boundary).\""},{"VolcanoId":"ak192","Vnum":311111,"Volcano":"Moffett","OfficialName":"Mount Moffett","ParentVolcanoId":"ak192","ParentVolcano":"Moffett","AgeClass":"SuspHolo","AgeSource":"Waythomas (1994) believes Mount Moffett had eruptions in the Holocene.","Composition":"mafic","IsMonitored":false,"VolcanoType":"Stratovolcano","NvewsThreat":"High Threat","Description":"   From Wood and Kienle (1990): \"Adak is a large Tertiary island in the central Aleutians with a small (~40 cubic km) volcanic center at its northern extremity.  Kanaga lies to the west and Great Sitkin to the east.  Because of its easy access, Adak is certainly the most frequently visited and sampled island in the Aleutians.  Andrew Bay (~350 m, oldest), Mount Moffet (1,200 m), and Mount Adagdak (650 m) volcanoes have produced essentially all the Recent volcanic material.  Only the erosional vestiges of Andrew Bay volcano remain (now filled by Andrew Bay and Lake); it was apparently obliterated by caldera formation, encroachment of the sea, and glaciation.  Heavily glaciated, Mount Moffet consists of principally of thick andesite flows, flank domes, and a substantial parasitic cone of many thin basalt flows.  The scoriaceous, blocky dome on the outward south flank of Mount Moffet may be one of the youngest volcanic features of this center.  Mount Adagdak is a model composite cone with a distinct lower shield of one or two basalt flows and interbedded scoria.  At ~350 m the small stratovolcano begins, consisting mainly of volcaniclastic debris and an occasionally thin, fragmentary andesitic flow.  The summit crater, with a well-defined south rim, is occupied by a hornblende andesite plug; in places it has vertical, smooth walls peppered with indigenous xenoliths.  At one time this plug may have been partly a Pelean spine, large blocks of which are scattered across the shield.  A northwesterly directed explosion and ash flow may have strongly breached the summit crater prior to the vent-filling event.  A late stage basaltic dome lies on the southeast flank.\r\n   \"Although Moffet and Adagdak are certainly volcanoes, when compared to large Aleutian volcanoes, both vents represent small, almost futile outpourings.  This is perhaps reflected in the heterogeneous nature and composition of the erupted materials.  Mafic, olivine-rich xenolithic material is common in a thick andesite flow on the north shore of Mount Moffet, and also in an apparently phreatic vent on the west shield of Mount Adagdak; gabbroic and dioritic xenoliths are found along the bouldery beach north of Mount Adagdak.\"","NameOrigin":"Mount Moffett was named by the U.S. Navy Hydrographic Office in 1936, after Rear-Admiral William Adger Moffett (Orth, 1971)."},{"VolcanoId":"ak3","Vnum":null,"Volcano":"Adagdak","OfficialName":"Mount Adagdak","ParentVolcanoId":"ak3","ParentVolcano":"Adagdak","AgeClass":"SuspHolo","AgeSource":"Mount Adagdak may have had Holocene eruptions (Waythomas, 1995).","Composition":"andesite","IsMonitored":false,"VolcanoType":"Stratovolcano","NvewsThreat":"Moderate Threat","Description":"   From Baten (2002)@3667@: \"Mt. Adagdak is located on the northeastern portion of Adak Island, central Aleutian Islands, Alaska.  Mt. Adagdak is built from three primary stages of volcanism: 1) the shield stage composed primarily of thick basaltic lava flows, 2) two composite cones, the older cone yields an 40Ar/39Ar date of 2.20 +/- 0.37 Ma (2 sigma error) and the younger cone has a date of 1.2 +/- 0.15 Ma and 3) three domes, one of which has a date of 0.21 +/- 0.05 Ma.\"\r\n   From Wood and Kienle (1990)@3284@: \"Adak is a large Tertiary island in the central Aleutians with a small (~40 cubic km) volcanic center at its northern extremity.  Kanaga lies to the west and Great Sitkin to the east.  Because of its easy access, Adak is certainly the most frequently visited and sampled island in the Aleutians.  Andrew Bay (~350 m, oldest), Mount Moffet (1,200 m), and Mount Adagdak (650 m) volcanoes have produced essentially all the Recent volcanic material.  Only the erosional vestiges of Andrew Bay volcano remain (now filled by Andrew Bay and Lake); it was apparently obliterated by caldera formation, encroachment of the sea, and glaciation.  Heavily glaciated, Mount Moffet consists of principally of thick andesite flows, flank domes, and a substantial parasitic cone of many thin basalt flows.  The scoriaceous, blocky dome on the outward south flank of Mount Moffet may be one of the youngest volcanic features of this center.  Mount Adagdak is a model composite cone with a distinct lower shield of one or two basalt flows and interbedded scoria.  At ~350 m the small stratovolcano begins, consisting mainly of volcaniclastic debris and an occasionally thin, fragmentary andesitic flow.  The summit crater, with a well-defined south rim, is occupied by a hornblende andesite plug; in places it has vertical, smooth walls peppered with indigenous xenoliths.  At one time this plug may have been partly a Pelean spine, large blocks of which are scattered across the shield.  A northwesterly directed explosion and ash flow may have strongly breached the summit crater prior to the vent-filling event.  A late stage basaltic dome lies on the southeast flank.\r\n   \"Although Moffet and Adagdak are certainly volcanoes, when compared to large Aleutian volcanoes, both vents represent small, almost futile outpourings.  This is perhaps reflected in the heterogeneous nature and composition of the erupted materials.  Mafic, olivine-rich xenolithic material is common in a thick andesite flow on the north shore of Mount Moffet, and also in an apparently phreatic vent on the west shield of Mount Adagdak; gabbroic and dioritic xenoliths are found along the bouldery beach north of Mount Adagdak.\"","NameOrigin":"Mount Adagdak's name was derived in 1948 by the U.S. Geological Survey from the name of nearby Cape Adagdak (Orth, 1971)."},{"VolcanoId":"ak146","Vnum":311130,"Volcano":"Kasatochi","OfficialName":"Kasatochi Island","ParentVolcanoId":"ak146","ParentVolcano":"Kasatochi","AgeClass":"Historical","AgeSource":"Historical eruption.","Composition":"unknown","IsMonitored":false,"VolcanoType":"Stratovolcano","NvewsThreat":"High Threat","Description":"   From Miller and others (1998): \"Kasatochi Island, like Gareloi, Bogoslof, and several other volcanoes in the western Aleutian arc, represents the emergent summit of a predominantly submarine volcano.  The island consists of a single, undissected cone with a central lake-filled crater about 0.75 km in diameter.  A maximum height of 314 m is on the southern crater rim; elevation of the lake is less than about 60 m.   Kay (1990) reports a lava dome on the northwest side of the cone at an elevation of ~150 m.\r\n   \"Coats (1956) referred to Kasatochi as one of a group of little-known volcanoes that appear to be stratovolcanoes composed of basaltic and andesitic flows and pyroclastics.  The mean slope of the southern flank (about 18 degrees) is considerably less than the mean slope of the northern flank (about 45 degrees).  This asymmetry of form may reflect a predominance of lava flows low on the southern flanks, or, it may be due to a higher rate of erosion by wave action from the north.  Bathymetry indicated that Kasatochi is at the northern end of a 15-km-long, 6-km-wide submarine ridge that is normal to the trend of the Andreanof Islands.  Water depths along the ridge are less than 90 m; if Kasatochi is constructed entirely on the ridge, the total height of the volcanic pile is only a little more than 400 m.\"","NameOrigin":"\"Kasatochi Island\" is a Russian name published as \"Kosatochyey\" by Lieutenant Sarichev (1802), shown as \"L'ile Kassatotchy\" by Lutke (1836), and as \"O[strov] Kasatochiy\" on the Russian Hydrographic Department Chart 1400 (1848) (Orth, 1971). Bergsland (1959) records the Unangam Tunuu place name of Kasatochi as \"qana-tanar,\" meaning \"which island,\" as in \"which island is it that is emerging out there.\""},{"VolcanoId":"ak17","Vnum":311160,"Volcano":"Atka volcanic complex","OfficialName":"Atka Island","ParentVolcanoId":"ak17","ParentVolcano":"Atka volcanic complex","AgeClass":"Historical","AgeSource":"Historical eruptions from Kliuchef.","Composition":"basalt","IsMonitored":true,"VolcanoType":"Stratocone with caldera and multiple satellite vents and stratovolcanoes","NvewsThreat":"High Threat","Description":"   From Wood and Kienle (1990): \"Atka is the largest (~200 cubic km) volcanic center in the central Aleutians.  There are no larger centers westward, and the closest larger center is Umnak, some 300 km east.  Seguam lies directly to the east, and Great Sitkin to the west.  The overall structure of the center is that of a broad central shield which once supported a large (~2,200 m) center cone (Atka volcano) ringed by as many as 7 or 8 smaller satellite volcanoes.  The central cone was lost to caldera formation, shutting down the whole system, and the satellite vents still remain at various stages of erosional decay.  Sarichef is perhaps the youngest satellite vent and has survived erosion largely unscathed.  More often, summit ice buildup has breached the crater walls, forming active cirques, which have deeply incised the satellite vents.  Tangential to these vents are U-shaped valleys, formed by moving ice.\r\n   \"Kliuchef volcano grew on the north rim of the now ice-filled Atka caldera and formed a series of five vents striking northeast.  The two main summit vents and the easternmost vent are fresh; the latter is most likely the source of the 1812 eruption attributed to Sarichef.  Double-coned Korovin volcano next appeared, although overlapping considerably in time with Kliuchef.  Six km north of Kliuchef, Konia volcano occupies the middle ground between Korovin and Kliuchef and is as old as much of Korovin itself.  Korovin has been and remains the principal active volcano on Atka.  It is unusual in that its summit crater marks an open, cylindrical vent reaching nearly to sea level; it has been observed by pilots flying over to sometimes contain a crater lake and at other times to be brimming with magma.  This vent is the source of most recent eruptions.\r\n   \"All the volcanoes consist principally of crystal-rich, thin, (\u003c~3m) basaltic lavas with interbedded scoria yielding increasing amounts of pyroclastic debris, autobreccias, and lahars.  The summit of Kliuchef is mostly glassy dacite as are some late flows of Korovin and Konia.  A thick (~400 m) pink dacite with pumiceous and glassy cooling units was erupted upon formation of Atka caldera, but no ash flows have been found.  Thick, expansive lahar aprons fill many early Pleistocene glacial valleys.  These have been cut by parse dikes spanning the volcanic center, whose emplacement apparently attended caldera collapse.  The lavas themselves are overwhelmingly (\u003eor= 90% by volume) high-alumina basalt, strikingly free of xenoliths.  The basalt contains plagioclase, orthopyroxene, magnetite, and clinopyroxene.  The andesite and dacite contain orthopyroxene at the expense of olivine; trace amounts of biotite are also found in the dacite.  No hydrous phases are found in any basalt or andesite lava.  Three hot spring areas are found apparently associated with Kliuchef and Atka caldera, and a fourth spring occurs some 7.5 km west of Kliuchef.\"","NameOrigin":"\"Atka Island\" comes from an Unangam Tunuu name reported by early Russian traders; published as \"Atchu Island\" by Rev. Coxe (1780), \"Atghka\" by Captain Cook (1785), \"Atkha Ile\" by Captain Lutke (1836), and \"O[strov] Atka on Captain Tebenkov's 1852 map (Orth, 1971)."},{"VolcanoId":"ak329","Vnum":311210,"Volcano":"Yunaska","OfficialName":"Yunaska Island","ParentVolcanoId":"ak329","ParentVolcano":"Yunaska","AgeClass":"Historical","AgeSource":"Historical eruptions.","Composition":"mixed","IsMonitored":false,"VolcanoType":"Shield volcano with caldera and associated stratovolcanoes, cinder cones, and lava field","NvewsThreat":"Moderate Threat","Description":"   From Miller and others (1998): \"Yunaska Island lies near the west end of the Islands of the Four Mountains group and is flanked by Chagulak and Amukta Islands on the west and the remainder of the group on the east.  Yunaska Island is roughly oval in form and about 23 km long.  It consists of two volcanic centers separated by a flat valley with moderately sloping walls.  The western volcano, 950 m high, is the eroded remnant of a series of four overlapping stratocones (Nicolaysen and others, 1992); a group of cinder cones and fissure flows extends from the west end of the complex.  This western volcano has presumably not been active in historical time.\r\n   \"The eastern volcanic center, to which all recent Yunaska volcanism has been attributed, has been described by Nicolaysen and other (1992) in preliminary reports as a large shield volcano topped by two overlapping calderas.  No age has been reported for caldera formation but the fresh morphology of the younger caldera and the non-glaciated nature of the associated pyroclastic rocks suggests it is at least Holocene in age.  The older of the two calderas (caldera CI, Lamb and others, 1992) has a diameter of 10-13 km, the younger (caldera CII) about 3 km.  Low ridges and peaks along the northern and eastern shores of the island define the postulated caldera (see physiographic descriptions in Sekora, 1973).  Sinuous ridges and small cones, craters, and lava flows of the active field occur both within and outside caldera II.  The most prominent flow extends 1.5 km south from the southwestern lip of caldera II but does not reach the sea.  A second area of relatively young lava flows lies north of the caldera, and a smaller flow is situated on the east flank.\r\n   \"Known cones and inferred lava vents outside the caldera are located within 1 km of the rim.  Within the caldera is a 500 m cone that has its own small summit crater.  Low relief on the eastern part of Yunaska Island implies that either the pre-caldera volcano had a shield-like form, or that a former cone has been subsequently destroyed.  No hot springs or active fumaroles are known to exist on the island.\"","NameOrigin":"\"Yunaska Island\" is an Unangax name, published by Sarichev (1826) as \"Os[trov] Yunaska\" (Orth, 1971)."},{"VolcanoId":"ak117","Vnum":311220,"Volcano":"Herbert","OfficialName":"Herbert Island","ParentVolcanoId":"ak117","ParentVolcano":"Herbert","AgeClass":"SuspHolo","AgeSource":"Fieldwork at Tana and Herbert (C. Neal and K. Nicolaysen,\r\npersonal commun., 2016) revealed the presence of high-temperature fumaroles. On the basis of morphology, Herbert is assumed to have had Holocene eruptions.","Composition":"unknown","IsMonitored":false,"VolcanoType":"Stratovolcano with caldera and linear ridge","NvewsThreat":"Low Threat","Description":"   From Wood and Kienle (1990): \"Herbert is a classic stratovolcano with a 2.1-km-wide caldera, which the topographic map indicates is breached to the northwest.  Radar images do not show the breach.  No geologic studies have been published on this volcano.  A grab sample from the tip of the island's southwest point is an andesite (59% SiO2, with 0.82% K2O).\"","NameOrigin":"Herbert Island was named by the U.S. Navy Hydrographic Office in 1894 for Hilary Abner Herbert, 1834-1919, Secretary of the Navy (Orth, 1971)."},{"VolcanoId":"ak52","Vnum":311240,"Volcano":"Cleveland","OfficialName":"Mount Cleveland","ParentVolcanoId":"ak52","ParentVolcano":"Cleveland","AgeClass":"Historical","AgeSource":"Historical eruptions.","Composition":"unknown","IsMonitored":true,"VolcanoType":"Stratovolcano","NvewsThreat":"High Threat","Description":"   From Miller and others (1998): \"Mt. Cleveland is a stratovolcano that comprises the entire western half of Chuginadak Island, 40 km west of Umnak.  Distinctively conical and symmetrical in form, Cleveland is about 8.5  km in diameter and is joined to the rugged, though lower, eastern half of the island by a low, narrow strip of land.  Sekora (1973) reports that this strip is dotted with \"lava flow, cinder, and ash patches, and conical hills.\"\r\n   \"Although it is the tallest member of the Four Mountains group, Mt. Cleveland is reported to lose snow more rapidly than neighboring peaks presumably from anomalous heat generation (Sekora, 1973, p. 27).  Hot springs were noted at the base of a volcano on Chuginadak Island in the 1800's (Waring, 1965).\r\n   \"Like many other Aleutian volcanoes, the lower flanks of Mt. Cleveland up to about the 300 m elevation are more irregular and dissected than the upper flanks.  The cones on the eastern half of Chuginadak Island are dissected by broad valleys presumably eroded in part by glaciers; in contrast, the upper cone of Mt. Cleveland is virtually undissected.\"","NameOrigin":"Mount Cleveland was named in 1898 by John A. Flemer, U.S. Coast and Geodetic Survey, possibly after Stephen Grover Cleveland, the 22nd and 24th President of the United States (Orth, 1971)."},{"VolcanoId":"ak307","Vnum":311270,"Volcano":"Vsevidof","OfficialName":"Mount Vsevidof","ParentVolcanoId":"ak307","ParentVolcano":"Vsevidof","AgeClass":"SuspHist","AgeSource":"Byers (1959) mapped Vsevidof as Holocene; may have had historical eruptions.","Composition":"mixed","IsMonitored":false,"VolcanoType":"Stratovolcano","NvewsThreat":"Moderate Threat","Description":"   From Miller and others (1998): \"Mount Vsevidof is a symmetrical stratovolcano near the southwest end of Umnak Island.  It is about 10 km wide at the base and steepens from 15 degrees at 300 m altitude to about 30 degrees near the summit.  A circular crater, 1.2 km in diameter, occupies the summit.  Glacial ice fills the crater and extends down the north and east flanks of the cone; some of these glacial tongues have incised narrow canyons up to 120 m deep.\r\n   \"A chain of small cinder cones (unit Qc) below altitude 1220 m parallels a rift on the western flank (Byers, 1959).  Young flows of andesite and dacite (unit Qvf) were extruded from this rift and from other vents on north and south flanks of the cone.  Pyroclastic deposits, apparently products of a culminating summit eruption, attain a thickness of more than 30 m at the crater but thin downslope.\r\n   \"The oldest Vsevidof flows (unit Qvba), are overlain by till of the last major glaciation, but the bulk of the cone is believed to be of post-glacial, i.e., Holocene, age.  The cone is locally underlain by hypersthene-andesite lava flows and pyroclastic rocks of the more deeply eroded Mount Recheschnoi.  Lava flows from both Recheschnoi and Vsevidof unconformably overlie a basement of probable early to middle Tertiary age including plutonic rocks (unit Tdp) and altered sedimentary and metamorphic rocks.\"","NameOrigin":"Mount Vsevidof's name is derived from the nearby Vsevidof Island, although Mount Vsevidof is located on Umnak Island. Vsevidof Island may have been named for Andrei Vsevidof, a Russian fur trader in the Aleutians circa 1747 (Orth, 1971)."},{"VolcanoId":"ak6","Vnum":311320,"Volcano":"Akutan","OfficialName":"Akutan Peak","ParentVolcanoId":"ak6","ParentVolcano":"Akutan","AgeClass":"Historical","AgeSource":"Historical eruptions.","Composition":"mafic","IsMonitored":true,"VolcanoType":"Stratovolcano with caldera","NvewsThreat":"Very High Threat","Description":"   From Miller and others (1998): \"Akutan volcano is a composite stratovolcano with a circular summit caldera about 2 km across and 60 to 365 m deep (Byers and Barth, 1953; Romick and others, 1990; Motyka and others, 1981) and an active intracaldera cinder cone.  The caldera rim reaches a maximum altitude of 1303 m at Akutan Peak, the remnant of a pre-caldera cone now filled with a lava plug.  The caldera is breached to the north.  Caldera subsidence accompanied or followed eruptions from a series of rim vents.  The vestige of a larger caldera, of probable late Pleistocene age and at least in part older than the cone of Akutan Peak, extends 1.5 km southwest of Akutan Peak and is terminated to the north by the younger caldera.  Small glaciers fill the older crater and lie within the southwest and southeast margins of the younger caldera.\r\n   \"The active intracaldera cinder cone is over 200 m high, about 1 km in diameter, and located in the northeast quarter of the caldera.  Three small sulfur-lined craters occupy its summit and several fumarole zones are present along its south and southwest flank (Byers and Barth, 1953).  A crescent-shaped lake along the inner southwest rim of the caldera and a hot and slightly acidic lake along the northern caldera wall were noted by Byers and Barth in 1948 but Motyka and others (1981) speculate that these lakes may have been obliterated by more recent activity.  Both lakes drained to the north through a gap in the caldera wall.\r\n   \"The lava flows and pyroclastic deposits of Akutan volcano are no older than Pleistocene as Romick and others (1990) report ages of 1.1 +/- 0.1 to 1.8 +/- 0.8 Ma for the oldest of these rocks.  The caldera-forming eruption occurred about 5,200 yBP (Reeder, 1983) and was the source of small volume andesitic pyroclastic-flow deposits in valleys on the north, south, and east sides of the volcano (Miller and Smith, 1987; Romick and others, 1990).  Young basaltic lava flows, some of which were erupted in 1929, cover the caldera floor south and north of the cinder cone and extend several hundred m downslope through the crater rim gap.  Flows extruded in 1947 blanket the central portion of the northwest end of the island at Lava Point, where about 4 square kilometers of jagged aa basalt occurs adjacent to several cinder cones.  The entire island is mantled by an ash layer that thickens toward Akutan Peak; landslide and mud flow deposits have concentrated this ejecta in the valleys north and northeast of the caldera and a maximum fill depth of 7 m occurs at Wooly Cove (Finch, 1935).\r\n   \"Active hot springs occur northeast of the caldera at the head of Hot Springs Bay valley and along the shore of Hot Springs Bay; Byers and Barth (1953) and Motyka and others (1990) recorded temperatures between 67 and 84 degrees C and a pH range of 6.6 to 7.  Surface waters of the hot caldera lake were 50 degrees C with a pH of 5.0 and steam issuing from fumaroles along the cinder cone base averaged 96 degrees C (Finch, 1935).\"","NameOrigin":"According to Orth, 1971, Akutan Peak's name was reported in 1873 by the U.S. Coast and Geodetic Survey, and presumably named by that agency.  Orth also reports that R.H. Geoghegan states that the name \"Akutan\" may be from the Aleut word \"hakuta,\" meaning, \"I made a mistake.\" However, Bergsland (1994) reports the Unangam Tunuu placename for Akutan Island as Akutanax̂, meaning \"the island over there, Akutan Island.\""},{"VolcanoId":"ak322","Vnum":311340,"Volcano":"Westdahl","OfficialName":"Westdahl Peak","ParentVolcanoId":"ak322","ParentVolcano":"Westdahl","AgeClass":"Historical","AgeSource":"Historical eruptions.","Composition":"mafic","IsMonitored":true,"VolcanoType":"Shield volcano","NvewsThreat":"High Threat","Description":"   From Miller and others (1998): \"Westdahl Peak, including nearby Faris Peak and Pogromni volcano, is located on a gently sloping plateau (mean elevation 1220 m) that may represent the surface of a truncated ancestral cone.  Westdahl Peak is about 18 km in diameter at the base.\r\n   \"The size of the postulated ancestral cone is about 19 x 30 km at sea level, making it one of the largest volcanoes in the Aleutian Islands be it a stratovolcano or a shield.  The entire ancestral cone has been extensively dissected by erosion, with the northeast-facing slopes steeper and of greater relief than the other slopes.\r\n   \"Based on the degree of erosional dissection, most of the postulated stratovolcano must have formed before early post-glacial time.  Pogromni Volcano is moderately dissected and has broad valleys that have probably been glacially eroded.  Such glacial erosion could have occurred during neoglaciation beginning about 3000 years ago (Black, 1974, table 1), although one or two thousand years seem inadequate to account for the degree of dissection.  Pogromni volcano was probably active by latest Pleistocene time, which implies that truncation of the ancestral stratovolcano must have occurred earlier.\"","NameOrigin":"Westdahl Peak was named in 1902 by O.H. Tittmann, for Ferdinand Westdahl of the U.S. Coast and Geodetic Survey, who determined its geographic position in 1901 (Orth, 1971)."},{"VolcanoId":"ak83","Vnum":312011,"Volcano":"Dutton","OfficialName":"Mount Dutton","ParentVolcanoId":"ak83","ParentVolcano":"Dutton","AgeClass":"Holocene","AgeSource":"Chertkoff and others (1999) believe that some of Dutton's domes are Holocene, based on morphology and 14C landslide dates.","Composition":"andesite","IsMonitored":true,"VolcanoType":"Stratovolcano with summit dome complex","NvewsThreat":"Moderate Threat","Description":"   From Miller and others (1998): \"Mount Dutton is a small snow- and ice-covered calc-alkaline volcanic center with an approximate diameter of 5 km (not including the isolated large intra-canyon lava flow 5 km southwest of the summit) and an estimated volume of 7-15 cubic km.  The volcano is built on an east-sloping basement of hydrothermally altered Tertiary volcanic rocks (Kennedy and Waldron, 1955).\r\n   \"The volcano consists of a central multiple dome complex (Davies and others, 1988) in which successive domes shouldered aside earlier domes and the enclosing cone-building volcanic rocks.  Some hydrothermal alteration occurs along vertical contacts between adjacent domes.  The dome-building activity and associated collapse has caused extensive destruction of cone-building lava flows and, to a lesser extent the domes themselves.  This has resulted in the massive, thick-bedded debris flows 100-200 m thick that surround and mantle the central dome complex.\r\n   \"A headwall scarp about 300 m high and dipping to the northwest about 45 degrees forms the west side of the summit.  Debris avalanches from this and lower areas moved down either side of the east-west oriented range crest.  The resulting avalanche deposits include blocks up to 5 m in diameter and are characterized by hummocky topography and small closed depressions.  The avalanche deposits cover a total area of about 11.4 square km and have an estimated volume of about 0.17 cubic km.\r\n   \"Only slightly dissected debris flows and pyroclastic flows occur on the east flank of the volcano.  Two flank-domes occur 3.5 km north-northeast of the summit of Mount Dutton at an elevation of 520 m.  These non-glaciated flank domes are assumed to represent Holocene eruptions.  Most, if not all, of the avalanche and debris flows that mantle the volcano's flanks are also Holocene in age.\"","NameOrigin":"T.A. Jagger named Mount Dutton in 1927, for Clarence Edward Dutton, a 19th century volcanologist (Orth, 1971)."},{"VolcanoId":"ak93","Vnum":312020,"Volcano":"Emmons Lake Volcanic Center","OfficialName":null,"ParentVolcanoId":"ak93","ParentVolcano":"Emmons Lake Volcanic Center","AgeClass":"Holocene","AgeSource":"Active fumaroles at Mt. Hague; CFEs in Pleistocene, intra-caldera eruptions in Holocene (Waythomas and others, 2006).","Composition":"mixed","IsMonitored":false,"VolcanoType":"Stratovolcano with caldera","NvewsThreat":"Moderate Threat","Description":"   From Wood and Kienle (1990): \"The Emmons Lake volcanic center is the site of a large stratovolcano with a pre-caldera volume of 300-400 cubic km and one of the largest calderas in the Aleutian arc.  The center is very complex; at least two large caldera-forming eruptions have occurred in Late Quaternary time, and voluminous post-caldera volcanism continues to the present.  The entire area has been subjected to multiple glaciations, and ice fields present occur in the caldera.  A small lake in the southwest corner of the caldera drains to the Pacific Ocean through a breach in the southeast rim of the caldera.\r\n   \"The pre-caldera Emmons Lake volcano was built on the northeast flank of a topographic basement high composed of Tertiary volcanogenic and intrusive rocks that are exposed at an elevation of over 900 m in the caldera wall west of Emmons Lake.  This period of volcanism consisted of an outpouring of andesitic basalt and volcaniclastic rocks over an area of 700 square km or more.  Following deep erosion and glaciation, a major caldera-forming eruption occurred, resulting in the deposition of welded ash-flow tuffs of rhyolitic composition on both the Bering Sea and Pacific Ocean flanks of the volcano.  In some cases, these welded tuffs filled deep valleys in the pre-caldera cone.  At least some post-caldera basaltic volcanism appears to have occurred at this time, principally associated with Mount Emmons.\r\n   \"A second caldera-forming eruption, probably in late Wisconsin time, resulted in the emplacement of non-welded rhyolitic ash-flow tuffs in all quadrants around the volcano to distances \u003e30 km from the caldera rim.\r\n   \"Renewed post-caldera volcanism appears to have been chiefly basaltic in character.  Within the caldera this activity has been characterized by aa and block lava flows emitted from several small cinder cones and vents.  Some of the young Holocene flows moved through the breach in the southern caldera wall and are found within a kilometer of the Pacific Ocean.  A large fumarolic area occurs on the south side of Mount Hague, which is near the eastern margin of the caldera.\"","NameOrigin":"\"Emmons Lake Volcanic Center\" is an informal name applied to the cluster of volcanoes near Mount Emmons and Emmons Lake."},{"VolcanoId":"ak211","Vnum":312040,"Volcano":"Pavlof Sister","OfficialName":"Pavlof Sister","ParentVolcanoId":"ak211","ParentVolcano":"Pavlof Sister","AgeClass":"SuspHolo","AgeSource":"Possible historical eruption. Waythomas and others (2006) believe that this volcano was active within the last 15,000 to near-historical times.","Composition":"basaltic_andesite","IsMonitored":false,"VolcanoType":"Stratovolcano","NvewsThreat":"Moderate Threat","Description":"   From Smithsonian Institution, online database, accessed December 8, 2003: \"Located at the end of a chain of volcanoes trending NE from Emmons Lake caldera, the symmetrical Pavlof Sister stratovolcano is somewhat more eroded than its twin volcano to the SW, Pavlof. The 2142-m-high Pavlof Sister is almost 400 m lower than Pavlof and has a sharper-peaked summit. Only one historical eruption, in the 18th century, was recorded from Pavlof Sister. The two symmetrical volcanoes form a dramatic backdrop to Pavlof Bay and Volcano Bay near the western end of the Alaska Peninsula.\"","NameOrigin":"The U.S. Geological Survey named Pavlof Sister in 1929 (Orth, 1971)."},{"VolcanoId":"ak72","Vnum":312050,"Volcano":"Dana","OfficialName":"Mount Dana","ParentVolcanoId":"ak72","ParentVolcano":"Dana","AgeClass":"Holocene","AgeSource":"Wilson and others (1995) have a 14C date of 3,840 +/- 100 for an organic layer underlying multiple ash layers and a block-and-ash flow from Mt. Dana.","Composition":"dacite","IsMonitored":false,"VolcanoType":"Dome complex","NvewsThreat":"Moderate Threat","Description":"   From Wood and Kienle (1990): \"Mount Dana is a small calc-alkaline volcanic center consisting largely of volcaniclastic debris surrounding a central dome or domes, reminiscent of Augustine volcano.  The volcano rests on relatively undeformed Jurassic and Cretaceous marine sandstone and shale.  Mesozoic sedimentary rocks, dipping steeply southwest, form the southwest crater rim and are exposed in the canyon at the crater outlet.  Remnants of a high-silica andesite dome are exposed on the west crater rim and in a small mound on the east side of Knutson Lake.  A block-and-ash flow erupted 3,840 yBP fills valleys south and west of the crater.  A 200-m-wide tufa mound and several cold springs occur at elevations of 490 to 520 m on the southwest flank.\"","NameOrigin":"\"Mount Dana\" is a local name for this volcano, reported by the U.S. Geological Survey in 1929 (Orth, 1971)."},{"VolcanoId":"ak305","Vnum":null,"Volcano":"Stepovak Bay 3","OfficialName":null,"ParentVolcanoId":"ak305","ParentVolcano":"Stepovak Bay 3","AgeClass":"Holocene","AgeSource":"Wilson (1989) says this volcano has a thick Holocene lava flow.","Composition":"andesite","IsMonitored":false,"VolcanoType":"Cinder cones","NvewsThreat":"Low Threat","Description":"   This volcano is a member of the Stepovak Bay group.  From Wood and Kienle (1990): \"The Stepovak Bay group is a chain of five volcanoes at the southwest end of a N40 degrees E oriented linear segment of the Aleutian arc on the Alaska Peninsula.  This same segment includes the better known Veniaminof and Aniakchak calderas.  Three of the Stepovak Bay volcanoes [2, 4, and Kupreanof] have clearly had Holocene eruptions, resulting in three small debris flows filling late Pleistocene glacial valleys, and a small cinder cone and associated lava flow.  The other two volcanoes (1 and 3) do not show unmistakable evidence of Holocene activity.  They have ice-filled summit craters 500 m (1) and 300 m (3) in diameter that may be late Pleistocene age.  These volcanoes have contributed to extensive late Tertiary and Quaternary lava flows, some extending near sea level.\"","NameOrigin":"\"Stepovak Bay 3\" is an informal name, after the nearby Stepovak Bay. As there are four unnamed volcanoes in this vicinity, they have been given numbers 1-4."},{"VolcanoId":"ak175","Vnum":312060,"Volcano":"Kupreanof","OfficialName":"Mount Kupreanof","ParentVolcanoId":"ak175","ParentVolcano":"Kupreanof","AgeClass":"SuspHist","AgeSource":"Kupreanof has had a possible historical eruption, and, based on morphology, is definitely Holocene.","Composition":"andesite","IsMonitored":false,"VolcanoType":"Stratovolcano","NvewsThreat":"Moderate Threat","Description":"   From Wood and Kienle (1990): \"The Stepovak Bay group is a chain of five volcanoes at the southwest end of a N40E oriented linear segment of the Aleutian arc on the Alaska Peninsula.  This same segment includes the better known Veniaminof and Aniakchak calderas.  Three of the Stepovak Bay volcanoes (2, 4, and Kupreanof) have clearly had Holocene eruptions, resulting in three small debris flows filling late Pleistocene glacial valleys, and a small cinder cone and associated lava flow.  The other two volcanoes (1 and 3) do not show unmistakable evidence of Holocene activity.  They have ice-filled summit craters 500 m (1) and 300 m (3) in diameter that may be late Pleistocene age.  These volcanoes have contributed to extensive late Tertiary and Quaternary lava flows, some extending near sea level.\r\n   \"Kupreanof is the largest and best known volcano of the group.  In 1982, reconnaissance mapping located the three southernmost volcanoes.  Later work further delineated these three, and located an additional center (4).  Mapping and K-Ar dating indicate the area has been the locus of voluminous volcanic activity for approximately the last 4 million years.  A fumarole occurs at Kupreanof volcano; another has been reported on volcano 4.  Air photos from the late 1940s also suggest the presence of a fumarole on volcano 1.\r\n   \"Northwest of the line of volcanoes a projected fault vertically offsets the volcanoes from flows that are related to the early history of the centers.  These flows, which dip away from the centers, yield K-Ar ages between 3.9 and 1.7 Ma.  Along the trend, and 7 to 12 km southwest of the volcanoes, is another area of early (?) Quaternary flows possibly related to a yet unrecognized center; outcrops of hypabyssal rocks in a snowfield among these flows may be this center.  The group of volcanoes overlies sedimentary rocks of Oligocene to late Miocene age; the southern centers also overlie thick tuff deposits of uncertain but presumably late Tertiary or early Quaternary age.\"","NameOrigin":null},{"VolcanoId":"ak328","Vnum":312100,"Volcano":"Yantarni","OfficialName":"Yantarni Volcano","ParentVolcanoId":"ak328","ParentVolcano":"Yantarni","AgeClass":"Holocene","AgeSource":"Riehle and others (1987) show that Yantarni had a catastrophic eruption no more than 3,500 years ago, and possibly as young as 2,000 years (using tephrochronology and radiocarbon dating).","Composition":"andesite","IsMonitored":false,"VolcanoType":"Stratovolcano with domes","NvewsThreat":"Moderate Threat","Description":"   From Wood and Kienle (1990): \"Yantarni volcano is an andesitic stratovolcano comprising ~3.5 cubic km located adjacent to, and within the same arc segment as, Mount Chiginagak.  The volcano was not discovered until 1979, owing to its modest summit elevation, remote location, and lack of documented historic activity.  Its name is taken from the adjacent bay, named on a Russian chart as \"Z. Yantarni\" for amber purportedly found there.  First mapped at a 1:250,000 scale, the volcano has since been mapped at 1:63,360 and its eruptive history and chemistry determined in greater detail.\r\n   \"The volcano formed near a high-angle fault at a site of previous Tertiary magmatism.  The current cycle of eruptive activity began in middle Pleistocene time with extrusion of andesitic lava flows, perhaps from multiple vents.  By the late Pleistocene, central-vent volcanism had initiated construction of a small stratovolcano.  The cone was breached in late Holocene time (between 2,000 and 3,500 yr ago?), forming a debris-avalanche deposit which was possibly accompanied by a directed blast and closely followed by emplacement of a dome and pyroclastic flows.  The pyroclastic flows are about 1 cubic km in volume and extend 4 km down-valley.\r\n   \"Disequilibrium phenocryst assemblages, a lack of correlation between phenocryst assemblages, and whole-rock compositions, eruption of different compositions of magma in close succession, and the small volume of eruptive products suggest Yantarni is an immature volcano lacking a large, shallow magma chamber.\"","NameOrigin":"Yantarni Volcano is named after nearby Yantarni Bay and Yantarni Creek. Russian explorers named Yantarni Bay and Yantarni Creek for the abundance of \"yantar\" or amber, found in the area (U.S. Board of Geographic Names GNIS, accessed February 12, 2009)."},{"VolcanoId":"ak151","Vnum":312120,"Volcano":"Kialagvik","OfficialName":null,"ParentVolcanoId":"ak151","ParentVolcano":"Kialagvik","AgeClass":"SuspHolo","AgeSource":"Detterman and others (1987), on the basis of the unglaciated morphology of some block-and-ash flows, think that Kialagvik has had eruptions in the Holocene.","Composition":"unknown","IsMonitored":false,"VolcanoType":"Stratovolcano with dome","NvewsThreat":"Moderate Threat","Description":"   From Wood and Kienle (1990): \"Kialagvik volcano is a small (~5 cubic km), poorly known central-vent volcano adjacent to, and in the same arc segment as Chiginagak volcano.  The volcano is informally named after the Eskimo word for the adjacent Wide Bay.  The published geologic map is at 1:250,000 scale; owing to remoteness and extensive snow and ice cover, little additional work has been done.\r\n   \"The volcano is constructed partly on and adjacent to older, early Quaternary (?) or Tertiary hypabyssal and extrusive rocks from other vents; consequently, the exact extent of the deposits properly assigned to the Kialagvik vent is uncertain.  Probable Kialagvik deposits comprise lava flows of andesitic composition and overlying dacitic block-and-ash flow deposits similar in composition to the Holocene (?) dome.  Except for lacking an exposed stratovolcano edifice, Kialagvik has probably been most similar in eruptive style to Yantarni volcano to the southwest.\"","NameOrigin":"\"Kialagvik volcano\" is an informal name, derived from nearby Kialagvik Creek."},{"VolcanoId":"ak296","Vnum":312131,"Volcano":"Ukinrek Maars","OfficialName":"Ukinrek Maars","ParentVolcanoId":"ak296","ParentVolcano":"Ukinrek Maars","AgeClass":"Historical","AgeSource":"Historical eruption (1977).","Composition":"basalt","IsMonitored":true,"VolcanoType":"Two maars","NvewsThreat":"Moderate Threat","Description":"   From Miller and others (1998): \"Ukinrek Maars are a pair of phreatomagmatic explosion vents that formed on a low (less than 100 m high), 4-km-long, ridge in the Bering Sea Lowland 1.5 km south of Becharof Lake and 12 km northwest of Peulik Volcano.  West Maar, elliptical in shape and up to 170 m in diameter and 35 m deep, formed on the northwest end of the ridge (Kienle and others, 1980).  East Maar lies 600 m east of West Maar at a lower elevation.  It is circular, up to 300 m in diameter and 70 m deep, and has a 49-m-high central lava dome that is now partly covered by a crater lake.  Location of the maars apparently coincides with, and may be controlled by, the intersection of the Bruin Bay fault and regional structures (Kienle and others, 1980; Detterman and others, 1983).\"","NameOrigin":"\"Ukinrek\" is a Yup'ik word meaning \"two holes.\" This feature was named after its formation in 1977."},{"VolcanoId":"ak299","Vnum":312132,"Volcano":"Unnamed (near Ukinrek Maars)","OfficialName":null,"ParentVolcanoId":"ak299","ParentVolcano":"Unnamed (near Ukinrek Maars)","AgeClass":"SuspHolo","AgeSource":"Detterman and others (1987) suggest that this dome is Holocene.","Composition":"unknown","IsMonitored":false,"VolcanoType":"Lava dome","NvewsThreat":"Low Threat","Description":"   From Smithsonian Institution (online database, accessed 2004): \"A small unnamed lava dome and an associated lava flow about 30 km east of Becharof Lake and 8 km NW of Alinchak Bay are not significantly modified by glacial erosion. Detterman and others (1987) suggested a Holocene age for the small dome, whose summit lies only about 300 m above sea level.\"","NameOrigin":"This feature does not have a formal or informal name."},{"VolcanoId":"ak189","Vnum":312140,"Volcano":"Martin","OfficialName":"Mount Martin","ParentVolcanoId":"ak189","ParentVolcano":"Martin","AgeClass":"Holocene","AgeSource":"Fierstein (2007) shows that Mt. Martin erupted lava coulees more than 6,000 years ago, and two tephras at ~3,700 and 2,700 14C yBP.","Composition":"andesite","IsMonitored":true,"VolcanoType":"Stratovolcano and lava-flow field","NvewsThreat":"High Threat","Description":"   From Miller and others (1998): \"Mount Martin is located near the center of a high (\u003e1400 m) ridge of altered basement rocks that extends more than 12 km, west-southwest form Mount Mageik (Riehle and others, 1987).  A crater, approximately 300 m in diameter and breached on its southeast side, occurs high on the east side of the summit cone.  The crater is the site of intense fumarolic activity and steam emission, and contains an ephemeral crater lake.  The summit cone and the voluminous lava-flow field, which fill the upper valley of Angle Creek northwest of the volcano, which are of Holocene age.  This flow-field, which erupted from a vent low on the north flank of the summit cone, covers approximately 31 square km and has volume in excess of 5 cubic km.  Martin's extent has previously been overestimated because the young volcano lies adjacent to the glaciated remnants of a mid-Pleistocene andesitic edifice (Alagogshak volcano).\"","NameOrigin":"R.F. Griggs named Mount Martin in 1919, after George C. Martin of the U.S. Geological Survey, who wrote the first authoritative report of the 1912 eruption of Novarupta and Katmai (Orth, 1971)."},{"VolcanoId":"ak187","Vnum":312150,"Volcano":"Mageik","OfficialName":"Mount Mageik","ParentVolcanoId":"ak187","ParentVolcano":"Mageik","AgeClass":"Holocene","AgeSource":"Fierstein (2007) shows that Mt. Mageik has frequently erupted during the Holocene, including seven explosive events from 9,400 to 2,400 14C yBP.","Composition":"andesite","IsMonitored":true,"VolcanoType":"Composite volcano","NvewsThreat":"High Threat","Description":"   From Miller and others (1998): \"Mount Mageik is a broad cone-shaped volcano that rests on a basement of Jurassic sedimentary rocks at the northeast end of a 12-km-long basement ridge shared by neighboring Mount Martin.  The summit area, which is largely ice-covered, consists of a central high peak (elevation 2165 m) and three smaller topographic highs, each a separate vent-cone.  A small (\u003c1 km in diameter) phreatic crater on the northeast side of the central peak contains a crater lake and supports vigorous fumarolic activity accompanied by sulfur deposition.  The slopes of the volcano are moderately dissected by glacial ice, except the young lava flows of the east side.  Two small debris avalanches, including the Mageik landslide - one of which occurred during the 1912 Katmai eruption (Griggs, 1922) originated from areas high and low on the south flank.  The 1912 avalanches, containing boulders as big as 3 to 5 m, traveled 6 km down the broad valley of Martin Creek, south and east of Mount Mageik.\"","NameOrigin":"\"Mount Mageik\" is reported in 1917 by R.F. Griggs as a Native name, and \"Mageik Volcano\" on his map and \"Mount Mageik\" in his text (Orth, 1971)."},{"VolcanoId":"ak288","Vnum":312160,"Volcano":"Trident","OfficialName":"Trident Volcano","ParentVolcanoId":"ak288","ParentVolcano":"Trident","AgeClass":"Historical","AgeSource":"Historical eruptions from Southwest Trident (1953-1974).","Composition":"andesite","IsMonitored":true,"VolcanoType":"Stratovolcano cluster","NvewsThreat":"High Threat","Description":"   From Miller and others (1998): \"Trident is an eroded volcanic complex consisting of three stratovolcanoes and numerous domes, as high as 1864 m in elevation, along a northeast-southwest oriented volcanic front on the Alaska Peninsula (Hildreth, 1987).  A new fragmental cone was built beginning in 1953 at an altitude of 1097 m in an amphitheater on the southwest flank of the southwest peak.\"","NameOrigin":"\"Trident Volcano\" is a descriptive name given by R.F. Griggs in 1916, because of its three prominent peaks (Orth, 1971)."},{"VolcanoId":"ak147","Vnum":312170,"Volcano":"Katmai","OfficialName":"Mount Katmai","ParentVolcanoId":"ak147","ParentVolcano":"Katmai","AgeClass":"Historical","AgeSource":"Historical eruption (1912).","Composition":"andesite","IsMonitored":true,"VolcanoType":"Stratovolcano with central caldera","NvewsThreat":"High Threat","Description":"   From Miller and others (1998): \"Katmai volcano is a large stratovolcano about 10 km in diameter with a central lake-filled caldera whose rim is about 4.2 by 2.5 km in area.  The caldera rim has a maximum elevation of 2047 m and in 1975 the lake surface was at an elevation of about 1236 m.  The estimated elevation of the caldera floor is about 995 m.\r\n   \"The volcano is one of five stratovolcanoes near the Novarupta dome, source of the voluminous pyroclastic flows erupted in 1912 (Hildreth, 1983).  It consists chiefly of lava flows, pyroclastic rocks, and non-welded to agglutinated air fall (Fenner, 1920; Hildreth, 1983).  The Quaternary volcanic rocks at Katmai and adjacent cones are less than 1500 m thick (Hildreth, 1983).  Much of the volcano is mantled by snow and ice and several valley glaciers radiate out from the flanks and three glaciers originating from the upper caldera walls descend into the crater to the lake (Motyka and Benson, 1975).\r\n   \"Katmai volcano is built on the sedimentary rocks of the Naknek Formation of Late Jurassic age, which are exposed just west of the caldera rim at an elevation of about 1520 m, as well as north and southeast of the crater (Curtis, 1968; Riehle and others, 1987).\"","NameOrigin":"This locality was published as \"Katmai Volcano\" in 1910 by the U.S. Coast and Geodetic Survey, and as \"Mount Katmai\" by G.C. Martin in 1913. \"Mount Katmai\" is the current proper name (Orth, 1971)."},{"VolcanoId":"ak203","Vnum":312180,"Volcano":"Novarupta","OfficialName":"Novarupta","ParentVolcanoId":"ak203","ParentVolcano":"Novarupta","AgeClass":"Historical","AgeSource":"Historical eruption (1912).","Composition":"mixed","IsMonitored":true,"VolcanoType":"Plinian pyroclastic vent with plug dome","NvewsThreat":"High Threat","Description":"   From Miller and others (1998): \"The Novarupta dome is about 400 m in diameter and 65 m high at its center (Curtis, 1968), and is surrounded by a 2-km-wide, funnel-shaped structure (Hildreth, 1983; Goodliffe and others, 1991).  The surface of the dome is completely fractured into chaotic blocks and crumble breccia.  The dome is a plug-like feature emplaced within a low ejecta ring.  Prominent scarps along the flanks of Baked, Falling, and Broken Mountains surrounding the Novarupta depression indicate considerable subsidence occurred following the 1912 eruption.  Nearby stratovolcanoes (including Trident and Katmai) form a volcanic front trending N65E; Novarupta lies about 4 km behind the front.  Linear fractures normal to the front extend between Novarupta and Trident (Hildreth, 1987).\"","NameOrigin":"R.F. Griggs named Novarupta in 1916. \"Novarupta\" means \"new eruption\"; the dome formed during the 1912 eruption of Novarupta and Katmai (Orth, 1971)."},{"VolcanoId":"ak74","Vnum":312210,"Volcano":"Denison","OfficialName":"Mount Denison","ParentVolcanoId":"ak74","ParentVolcano":"Denison","AgeClass":"SuspHolo","AgeSource":"Nye and others (1998) presumed Denison was Holocene in age.","Composition":"andesite","IsMonitored":false,"VolcanoType":"Stratovolcano","NvewsThreat":"Moderate Threat","Description":"   From Smithsonian Institution, online database, accessed December 8, 2003: \"Mount Denison lies near the head of the Serpent Tongue, Hook, and Hallo glaciers NE of Snowy volcano. This poorly known section of Katmai National Park contains a cluster of four closely spaced and mostly ice-covered vents. Mount Denison lies at the SW end of this volcanic chain, which also includes Steller, Kukak, and Devils Desk volcanoes. Orientation of lava flows and a thick cross-bedded tephra deposit suggest that a vent is located near Mount Denison (Swanson, in Wood and Kienle 1990). The precise age of the most recent activity at Denison is not known, but the volcano was considered to have been active during the Holocene (Nye and others, 1998).\"","NameOrigin":"Mount Denison's name was suggested by K.F. Mather, an alumnus of Denison University, Granville, Ohio. Brooks published the name in 1925 (Orth, 1971)."},{"VolcanoId":"ak265","Vnum":312220,"Volcano":"Steller","OfficialName":"Mount Steller","ParentVolcanoId":"ak265","ParentVolcano":"Steller","AgeClass":"SuspHolo","AgeSource":"Nye and others (1998) presumed Steller was Holocene in age.","Composition":"andesite","IsMonitored":false,"VolcanoType":"Stratovolcano?","NvewsThreat":"Moderate Threat","Description":"   From Smithsonian Institution, online database, accessed December 8, 2003: \"Mount Steller is part of a chain of closely spaced NE-SW-trending vents in Katmai National Park and lies between Mount Denision and Kukak volcanoes. Uncertainty surrounds the number and location of volcanic vents in this heavily glaciated area. The precise age of the most recent activity at Steller volcano is not known, but the volcano was considered to have been active during the Holocene (Nye and others, 1998).\"","NameOrigin":"Mount Steller was named in 1928 by the U.S. Geological Survey, for George Wilhelm Steller, a naturalist with Vitus Bering's 1741 voyage (Orth, 1971)."},{"VolcanoId":"ak77","Vnum":null,"Volcano":"Devils Desk","OfficialName":"Devils Desk","ParentVolcanoId":"ak77","ParentVolcano":"Devils Desk","AgeClass":"Pleistocene","AgeSource":"Hildreth and others (2003) have a K-Ar date for Devils Desk at about 245 ka.","Composition":"andesite","IsMonitored":false,"VolcanoType":"Stratovolcano","NvewsThreat":null,"Description":"From Wood and Kienle (1990)@3284@: \"Devils Desk is a volcanic neck of a former stratovolcano now completely surrounded by Hook Glacier.  Total relief from the top of Hook Glacier to the top of Devils Desk is ~450 m.  Extensive erosion has removed most of the stratovolcano.  Three radial dikes (now exposed as ridges) extend outward from the Desk toward the east.\" Hildreth and others (2003)@3470@ dated a block of lava from the southwest face of Devils Desk at 245 +/- 42 ka.","NameOrigin":"R.H. Sargent named Devils Desk in 1924 (Orth, 1971)."},{"VolcanoId":"ak143","Vnum":312250,"Volcano":"Kaguyak","OfficialName":"Kaguyak Crater","ParentVolcanoId":"ak143","ParentVolcano":"Kaguyak","AgeClass":"Holocene","AgeSource":"Fierstein (2007) shows that Kaguyak had a caldera forming event at 5,800 14C yBP.","Composition":"mixed","IsMonitored":false,"VolcanoType":"Stratovolcano with caldera","NvewsThreat":"High Threat","Description":"   From Wood and Kienle (1990): \"Kaguyak is a stratovolcano abbreviated by a caldera.  The highest point on the caldera rim (901 m) is over 550 m above a crater lake (depth \u003e180 m) that partially fills the caldera.  The lake is 2.5 km in diameter.  Exposed in the walls of the caldera are pre-caldera agglomerates, lava flows, dikes, and some small plugs.  A saddle on the northwest rim of the caldera represents a pre-caldera stream valley that was beheaded by caldera formation.\r\n   \"An extensive apron of pyroclastic flow deposits surrounds Kaguyak crater.  These deposits consist of white dacitic tephra and pumice and are the result of the caldera-forming eruptions.  Immediately after eruption, the pyroclastic flows filled the stream valleys around the volcano.  Subsequent stream erosion has provided exposures up to 30 m thick of the pyroclastic flows, but the base of the deposits has not been observed.  A paleosol immediately on top of the pyroclastic flow deposits yields a C14 date of 1,060 yr BP; this is a minimum age for the caldera-forming eruption.  The caldera has not been modified by glacial activity, thus making its origin post-glacial.\r\n   \"Both pre- and post-caldera domes are found at Kaguyak Crater.  A pre-caldera dome (elevation 706 m) on the southeast flank of the volcano is heavily mantled by caldera-related pumice, while a post-caldera dome (elevation 616 m) on the east flank does not have any pumice mantle.  Within the caldera two large post-caldera domes (elevation 614 m, 1 km diameter) have coalesced on the southwest edge of the caldera.  A smaller dome forms an island rising ~10 m above the center of the lake.  Weak solfataric activity has been reported from this dome but was not seen in 1982.\r\n   \"Kaguyak is better known than some of the other Katmai volcanoes.  Caldera formation resulted from the eruption of a dacite with phenocrysts of augite, hypersthene, hornblende, quartz, and plagioclase.  The extensive pyroclastic deposits surrounding Kaguyak suggest that tephra from the eruption might be widespread and, indeed, possible correlative tephras have been found 100 km from the volcano.  Work is in progress to better define the timing of caldera formation and the petrochemical evolution of the Kaguyak system.\"","NameOrigin":"Kaguyak Crater was named in 1951 by the U.S. Geological Survey after the nearby village of Kaguyak, which is now abandoned (Orth, 1971)."},{"VolcanoId":"ak80","Vnum":312270,"Volcano":"Douglas","OfficialName":"Mount Douglas","ParentVolcanoId":"ak80","ParentVolcano":"Douglas","AgeClass":"SuspHolo","AgeSource":"Nye and others (1998) considered Douglas to have erupted during the Holocene.","Composition":"andesite","IsMonitored":false,"VolcanoType":"Stratovolcano","NvewsThreat":"High Threat","Description":"   From Wood and Kienle (1990): \"Mount Douglas is a dissected stratovolcano covered by ice of the Spotted Glacier.  The summit of the volcano is marked by a crater with a small (160 m wide) crater lake.  An active fumarole field on the north side of the crater keeps the area free of ice.  A black scum floating on the lake in 1980 was probably sulfide minerals of some sort (consistent with a lake temperature of 25 degrees C and a pH of 1 measured in 1982).\r\n   \"Much of the volcano has been subjected to glacial erosion, but a ramp of lava flows on the northwest flank is relatively uneroded.  Most of the volcano is ice-covered, but isolated outcrops of lava flows (high-silica andesite) are found within the ice.  Reconnaissance geologic surveys suggest that the lavas extend to elevations lower than glacier's, but this has not been confirmed on the ground.\r\n   \"No historic activity has been reported for Mount Douglas; however, the presence of unglaciated lava flows and the active fumaroles indicate recent activity.\"","NameOrigin":"Mount Douglas' name was derived from Cape Douglas, and reported by G.C. Martin in 1904 (Orth, 1971)."},{"VolcanoId":"ak260","Vnum":313040,"Volcano":"Spurr","OfficialName":"Mount Spurr","ParentVolcanoId":"ak260","ParentVolcano":"Spurr","AgeClass":"Historical","AgeSource":"Historical eruptions (1953, 1992)","Composition":"andesite","IsMonitored":true,"VolcanoType":"Stratovolcano and explosion caldera","NvewsThreat":"Very High Threat","Description":"   From Miller and others (1998): \"Mount Spurr is a Quaternary stratovolcano located near the northeastern end of the Aleutian volcanic arc.  It is the easternmost historically active volcano in the Aleutian arc and is the highest of several snow- and ice-covered peaks that appear to define a large, dissected stratovolcano (Juhle and Coulter, 1955).\r\n   \"Capps (1929) suggested that a summit caldera, largely buried by ice, is associated with Mount Spurr.  Later, Juhle and Coulter (1955) disagreed with the caldera interpretation suggesting that the peaks around Mount Spurr only coincidentally resemble the rim of a large subsidence structure.  Most recent studies, however, suggest that ancestral Mt. Spurr, constructed during late Pleistocene time (Turner and Nye, 1986), was partially destroyed by a major Bezymianny-type eruption possibly as late as early Holocene time (Riehle, 1985; Nye and Turner, 1990).  The eruption produced a voluminous volcanic debris avalanche and subsequent pyroclastic flows that resulted in the formation of a 5- to 6-km-diameter explosion caldera.  The volcanic debris avalanche contains blocks as much as 100 m in diameter and traveled a minimum of 25 km.  The overlying pyroclastic flows are partially welded and are composed chiefly of high silica andesite.  Present Mt. Spurr is the highest of several post-caldera, centrally located, ice-carved cones or domes.\r\n   \"The youngest volcanic feature at Mount Spurr is a satellitic cone, Crater Peak, located in the breach in the caldera about 3.2 km south of Mount Spurr.  Crater Peak has a summit crater that is itself slightly breached along the south rim; the north wall of the crater exposes the truncated remains of an older dome or lava lake.  Crater Peak has been the source of all Late Holocene eruptive activity at Mt. Spurr (Riehle, 1985).  Before the 1992 eruption, a small crater lake occupied the bottom of the crater.\"","NameOrigin":"A.H. Brooks named Mount Spurr in 1900, for Josiah Edward Spurr, a U.S. Geological Survey geologist who led an expedition in the area in 1898 (Orth, 1971)."},{"VolcanoId":"ak116","Vnum":313050,"Volcano":"Hayes","OfficialName":"Hayes Volcano","ParentVolcanoId":"ak116","ParentVolcano":"Hayes","AgeClass":"Holocene","AgeSource":"Riehle and others (1990) date a set of tephra layers from Hays to between 3800 and 3500 14C yBP (4190 and 3780 cal yr).","Composition":"unknown","IsMonitored":false,"VolcanoType":"Stratovolcano remnant","NvewsThreat":"High Threat","Description":"From Wood and Kienle (1990): \"Hayes volcano was discovered in 1975 and is informally named for the adjacent Hayes Glacier.  Hayes is almost totally ice-covered.  No fumaroles have been observed during site visits in three different years.  Little is known of the volcano except that it is the site of catastrophic eruptions that deposited six regional tephra beds to the south, east, and northeast between about 3,500 and 3,800 yr ago.  The average volume of each of the six beds is about 2.4 cubic km.  The tephra-forming eruptions may have been accompanied by emplacement of a dome, although no such feature has been positively identified.  A thin, poorly preserved tephra bed northeast of the vent may be evidence of late Holocene activity subsequent to the catastrophic eruptions.\"","NameOrigin":"Hayes Volcano was officially named in 1999. The name is associated with Hayes Glacier, which was named for Charles Willard Hayes (1858-1916), a geologist and explorer \u003ca href=\"https://edits.nationalmap.gov/apps/gaz-domestic/public/gaz-record/1841449\"\u003e(link to GNIS)\u003c/a\u003e."},{"VolcanoId":"ak125","Vnum":314020,"Volcano":"Imuruk Lake Volc Field","OfficialName":null,"ParentVolcanoId":"ak125","ParentVolcano":"Imuruk Lake Volc Field","AgeClass":"Holocene","AgeSource":"Wood and Kienle (1990) report that The Lost Jim Flow, part of the Imuruk Lake volcanics, was erupted 1,655 yBP (radiocarbon dating).","Composition":"basalt","IsMonitored":false,"VolcanoType":"Monogenetic volcano field","NvewsThreat":"Very Low Threat","Description":"   From Wood and Kienle (1990): \"The Imuruk basaltic volcanic field consists of ~75 vents (mostly small cones) surrounded by lava flows.  Cones generally fed a single flow, and range in height from as little as 3 m to as much as 30 m.  Some cones are little more than spatter ramparts at the highest parts of flows.  The largest, and most recent, cone is the Holocene Lost Jim cone which is 30 m high and surmounted by a crater 30 m in diameter and 12 m deep.  There are a few small shield-shaped volcanoes which were also probably monogenetic.  Representative of these are the Twin Calderas, which are 120 m high with craters 500 to 750 m in diameter and 15 to 35 m deep.  Flows are generally pahoehoe and have surface relief averaging only a few meters.  There are a few aa and block lava flows.  Lava flows are a few to a few tens of meters thick at their distal ends and up to a few tens of kilometers long.  Only two flows are young enough that their geometry can be recognized clearly: the Late Pleistocene Camille flow extends 39 km west from its vent, and the Holocene Lost Jim flow extends 35 km west and 9 km north of its vent and covers ~230 square km.\r\n   \"Four major stratigraphic units have been recognized based on degree of weathering and nature of overlying deposits.  From youngest to oldest these are: the Holocene Lost Jim Flow, the Pleistocene Camille Flow, and the Pliocene and early Pleistocene Gosling and Imuruk volcanics.  The Lost Jim Flow erupted 1,655 yr BP, and the Gosling volcanics have ages of 0.9 and 0.8 Ma.  The Imuruk volcanics have been dated at 5.7 to 2.2 Ma.  A fifth unit, the Kugruk volcanics, is Oligocene and probably unrelated to late Cenozoic volcanism.  Ages of the Gosling and Imuruk volcanics are typical of other basalt fields in the Bering Sea region.  The Imuruk volcanics have the greatest areal extent of the lava units and cover nearly 2,300 square km.  The Imuruk basalt field lies in an area of broad structural warping accompanied by normal faulting.  Fault scarps as high as 30 m, and as long as 5 km, trend northwest and north-northeast cutting units as young as the Gosling volcanics.\r\n   \"Geochemical data are sparse but suggest that among Quaternary basalts the older, more voluminous Imuruk volcanics are dominantly subalkaline while the younger, less voluminous basalts are mainly alkalic.  The latter contains ultramafic nodules.\"","NameOrigin":"\"Imuruk Lake\" is an Inupiaq name reported in 1901 as \"Emuruk\" by Mendenhall in 1902 (Orth, 1971)."},{"VolcanoId":"ak169","Vnum":314030,"Volcano":"Kookooligit Mountains","OfficialName":"Kookooligit Mountains","ParentVolcanoId":"ak169","ParentVolcano":"Kookooligit Mountains","AgeClass":"Pleistocene","AgeSource":"Patton and Csejtey (1980) published 5 K-Ar age dates for Kookooligit lava flows, ranging from 1.46 Ma to 0.24 Ma. Mukasa and others (2007) have a single 40Ar/39Ar age date of 1.22 +/-0.02 Ma.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Shield volcano with cinder cones","NvewsThreat":null,"Description":"   From Wood and Kienle (1990): \"The Kookooligit volcanic field, on northern St. Lawrence Island, is one of a number of basalt fields in the Bering Sea region.  The field consists of an elongate shield volcano over 500 m high composed of massive columnar-jointed basalt flows overlain by \u003e100 small cones (20 to 60 m high) aligned east-west along a volcanic highlands.  The older volcanic flows are chiefly alkali olivine basalts and olivine tholeiite.  The younger cones and flows are dominantly basanite and alkali olivine basalt with subordinate hawaiite and nephelanite.  Most of the basanite and nephelanite flows and cones contain inclusions of deformed periodotite or gabbro; some also contain megacrysts of anorthoclase.\r\n   \"Most of the young volcanic rocks have primitive whole-rock compositions characterized by high MgO and low SiO2 contents.  The suite is characterized by decreasing total alkalies with increasing SiO2, similar to the trend observed in Hawaiian lavas.\"","NameOrigin":"\"Kookooligit Mountains\" is a  Yup'ik name reported in 1921 by the U.S. Coast and Geodetic Survey (Orth, 1971)."},{"VolcanoId":"ak262","Vnum":314040,"Volcano":"St. Michael","OfficialName":"Saint Michael Island","ParentVolcanoId":"ak262","ParentVolcano":"St. Michael","AgeClass":"SuspHolo","AgeSource":"Mukasa and others (2007) produced several 40Ar/39Ar age dates for the St. Michael volcanic field: from 0.80 +/-0.03 Ma, to (at Crater Mountain) 0.37+/-0.02 Ma). Aboriginal legends suggest that that most recent eruptions were 2000-3000 years ago.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Monogenetic cone field","NvewsThreat":"Moderate Threat","Description":"   From Wood and Kienle (1990): \"The St. Michael volcanic field is one of a number of late Tertiary and Quaternary, alkaline to subalkaline basaltic volcanic fields in the Bering Sea region of western Alaska.  The volcanic field covers all of St. Michael and Stuart Islands, extending inland as far as the Golsovia and Kogok rivers.  It consists of \u003e55 cones and craters and numerous flat-lying flows and tuffs covering \u003e3,000 square km.  The section of flows has a maximum thickness of 40 m exposed in sea cliffs along Norton Sound, but is probably much thicker in the interior of the field.  Most of the volcanic field consists of flat-lying tholeiitic or alkali-olivine basalt flows which appear to be erupted from broad shield volcanoes, such as those comprising St. Michael Mountain and Stuart Mountain.  These older dissected shield volcanoes are ~4 km across and 150 m high.  Young steep-sided cinder cones consisting of alkali-olivine basalt, basanite, or hawaiite overlie the flat-lying flows.  The cones and flows surrounding Crater Mountain, in the western part of the field, consist of highly alkalic basanite containing lherzolite nodules.  Most of the cones in \"The Sisters\" region are basanite or alkali olivine basalt, although a small group of cones ~4 km northeast of \"The Sisters\" are olivine tholeiite.  The alkalic cones in \"The Sisters\" region are aligned east-west, possibly following a fracture.  These young, small cones are 200-700 m across and ~40-75 m high.  A Holocene flow and two associated cones in the south-central part of the volcanic field are tholeiite.  Seven maar volcanoes occur on St. Michael Island in the northwest part of the field.  The western half of Stuart Island is made of young tholeiitic aa flows, probably erupted from a vent at West Hill.\"","NameOrigin":"\"St. Michael volcanic field\" is an informal name, after Saint Michael Island. The volcanic field covers Saint Michael Island, as well as Stuart Island, and extends inland as well. Saint Michael Island's name was reported as \"Ostrov Mikhaila\" by Zagoskin (Orth,1971)."},{"VolcanoId":"ak127","Vnum":314030,"Volcano":"Ingakslugwat Hills","OfficialName":"Ingakslugwat Hills","ParentVolcanoId":"ak127","ParentVolcano":"Ingakslugwat Hills","AgeClass":"SuspHolo","AgeSource":"Moll-Stalcup, in Wood and Kienle (1990) suggested that some of the activity at Ingakslugwat Hills has occurred in the Holocene.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Monogenetic volcano field, at least 32 small cinder cones and 8 larger craters","NvewsThreat":"Low Threat","Description":"   From Wood and Kienle (1990): \"The Ingakslugwat Hills volcanic field consists of \u003e32 small cinder cones and 8 larger craters with associated flows, all covering an area of \u003e500 square km.  Older vents are low, wide cones with saucer-shaped craters up to 1.5 km in diameter; younger eruptions formed relatively small, steep cones 30 to 90 m high and 90 to 150 m wide.  Numerous small spatter cones and cinder cones ~30 m high occur on the northwest side of the volcanic field.  Some cones are aligned west-northwest, apparently defining a fracture.  One low cone with a lake ~400 m across may be a maar.  The rocks are chiefly alkali olivine basalt with lesser amounts of  basanite and nephelanite.  The eruptive history of this field is unknown, but the well-preserved volcanic morphology suggests that some of the activity occurred in the Holocene.\r\n   \"Inclusions of lherzolite, layered gabbro, and granular gabbro occur in nephelnite ash and in an alkali basalt flow erupted from a cone in the southwest part of the Ingakslugwat Hills.\"","NameOrigin":"\"Ingakslugwat Hills\" is a Yup'ik name reported in 1948 by U.S. Coast and Geodetic Survey, who reported it means \"little old small mountains\".  They are referred to as \"The Volcanoes\" by the \"bush pilots\", according to Orth, 1965 (Orth, 1971)."},{"VolcanoId":"ak204","Vnum":314060,"Volcano":"Nunivak Island","OfficialName":"Nunivak Island","ParentVolcanoId":"ak204","ParentVolcano":"Nunivak Island","AgeClass":"Pleistocene","AgeSource":"Hoare and others (1968) obtained K-Ar dates for Nunivak Island ranging from 1.6 to 0.6 Ma. Mukasa and others (2007) obtained 40Ar/30Ar dates for the eastern end of Nunivak Island of 0.7 Ma and 0.15 Ma.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Shield?","NvewsThreat":null,"Description":"   From Wood and Kienle (1990): \"The volcanic carapace of Nunivak Island is built on Cretaceous sedimentary rocks in the eastern Bering Sea, within 50 km of western Alaska.  The surface of the island is dominated by broad thin pahoehoe lava flows, with subsidiary alkalic basalts forming small lava flows, ~60 cinder cones and 4 maars.  The pahoehoe flows are 3-15 m thick and build small shield volcanoes.  Exposures are best at sea cliffs and among the young flows of the eastern part of the island, which is otherwise covered with tundra and shallow lakes.  Permafrost is ubiquitous.\r\n   \"Alkali basalt lava flows are \u003c3.5 km long, and most erupted from cinder cones.  Some flows contain collapsed lava tubes and rafted segments of cinder cones.  Although many true cinder cones occur on Nunivak Island, some alkali basalt cones (e.g. Twin Mountain) have small summit craters and steep flanks, much more like small stratovolcanoes.  Alkali basalts also erupted phreatomagmatically, forming 4 maars in an east-west line: Binalik, Ahkiwiksnuk, Nanwaksjiak, and \"385,\" which is the elevation in feet of the crater lake of an otherwise unnamed maar.  The latter 2 maars have ~200 m of relief, with floors near sea level.  Although various types of nodules are found in many of the alkali basalt cones, ejecta from Nanwaksjiak includes lherzolite xenoliths within tholeiite boulders, an apparently unique occurrence.\r\n   \"Detailed radiometric dating demonstrated that volcanism occurred in distinct episodes, and systematically migrated eastward (~50 km/5 Ma).  Additionally, tholeiites and alkali basalts erupted nearly simultaneously.  Five pulses of volcanism (some combined in listing above), each lasting ~0.1-0.2 m.y., and separated by quiescent intervals of 1-2 m.y., occurred between 6 and 1.5 Ma.  Since 0.9 Ma volcanism has been frequent, with both tholeiite and alkali basalt common, but since 0.3 Ma only alkali basalt has been erupted.  The overlapping occurrence of the two magma types differs from the more familiar patter of tholeiite followed by alkali basalt in Hawaii, and suggests that at Nunivak the latter is not derived from the former.\"","NameOrigin":"Captain Lieutenant M.N. Vasiliev \"discovered\" Nunivak Island on July 21, 1821, and named it after his ship the Otkritie. A.K. Etolin and Khromchenko of the Russian American Company found the island at about the same time. Captain F.P. Lutke stated that the Native name \"Nounivak\" had been properly retained on charts, and added, had this course been followed in other cases, much confusion and embarrassment would have been avoided (Orth, 1971)."},{"VolcanoId":"ak264","Vnum":314010,"Volcano":"St. Paul Island","OfficialName":"Saint Paul Island","ParentVolcanoId":"ak264","ParentVolcano":"St. Paul Island","AgeClass":"Holocene","AgeSource":"Winer and others (2003) present 40Ar/39Ar age dates for St. Paul that have volcanism beginning 540,000 years ago, and continuing to at least 3230 yBP.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Monogenetic volcano field","NvewsThreat":"Very Low Threat","Description":"   From Wood and Kienle (1990): \"St. Paul is the largest of the Pribilof Islands, the emergent parts of a lava-topped structural high on the western edge of the Bering Sea shelf.  St. George Island is described elsewhere in this volume; Otter and Walrus Islands and Sea Lion Rock are smaller volcanic islands of unknown age in the group.  Most of St. Paul consists of coalescing small volcanoes, each composed of a central cinder cone and a surrounding shield of Quaternary lava flows.  Most flows are of the pahoehoe type, but at least three are aa.\r\n   \"There is no evidence of glaciation on St. Paul, but the youthful volcanic topography has been modified by frost action, deposition of wind-blown sand, faulting, and perhaps, folding.  A lava flow near Tolstoi Point has been broken up by closely spaced and gaping tectonic faults and fissures as much as 30 m deep, 50 m wide, and hundreds of meters long.\r\n   \"The lava flows are interbedded with marine sediments, and pillow lava is exposed in Einahnuhto Bluffs (western St. Paul).  Eolian and colluvial sediments are also interbedded with or cover many of the flows.  Most of the northern and eastern parts of the island are covered by wind-blown sand.\r\n   \"The cinder cones or cone complexes rise 30-100 m above their bases; 12-15 cones or cone complexes exceed 0.5 km in basal diameter.  The cones are composed of pyroclastic material that includes primarily basaltic tuff; there is one rare occurrence of rhyolitic pumice in the central eastern part of the island.  A maar is exposed in cross-section at Black Bluffs (east of the village of St. Paul), and many flows are patchily zeolitized, a process that may have occurred during initial cooling.  A tuffaceous marine gravel at the base of Black Bluffs that hosts Pliocene diatom flora indicates a history of Miocene or Pliocene volcanism.\"","NameOrigin":"\"St. Paul Island volcanic field\" is an informal name, after Saint Paul Island, which is covered by the volcanic field. Saint Paul Island was named by Russian hunters, on June 28, 1787, when they could see Saint Paul Island from Saint George Island. They originally named it \"Saint Peter and Saint Paul\" because it was the dedicated day of those two Apostles. The first half of the name was soon lost in popular usage (Orth, 1971)."},{"VolcanoId":"ak35","Vnum":315001,"Volcano":"Buzzard Creek","OfficialName":null,"ParentVolcanoId":"ak35","ParentVolcano":"Buzzard Creek","AgeClass":"Holocene","AgeSource":"Albanese (1980) gives three 14C dates which provide an age of eruption of ~3,000 yr BP. Andronikov and Mukasa (2010) attempted to use 40Ar/39Ar to date Buzzard Creek maars, and obtained a less than 10,000 years old result.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Tuff rings","NvewsThreat":"Low Threat","Description":"   From Wood and Kienle (1990): \"The Buzzard Creek craters are two tuff rings at the headwaters of Buzzard Creek, a tributary of the Totatlanika River, near Healy at the northern foot of the central Alaska Range.  The two craters are shallow and contain small lakes.  Rim ejecta contain 80% country rock fragments and 20% juvenile basaltic material, suggesting a phreatomagmatic origin.  The basalt rests on the youngest glacial terraces on Buzzard Creek, which are correlated with the Riley Creek glaciation that ended ~10,000 yr BP.  Three C14 dates from charcoal samples above and below the basaltic ejecta give an age of eruption of ~3,000 yr BP, in agreement with stratigraphic evidence of a Holocene age.  A 300-m-wide ejecta blanket associated with the larger crater can be traced 1.6 km from the vent.  The total volume of the ejecta probably does not exceed 1 million cubic m, of which only 20% is volcanic, consisting of vesicular basalt lapilli and small bombs.\r\n   \"The Buzzard Creek craters, though insignificant in the volume of ejecta, are of regional tectonic interest because they occur on trend with the Aleutian arc structure and are situated directly over the northernmost corner of the subducting Pacific plate.  The easternmost known volcano of the Aleutian arc is Hayes volcano, 320 km southwest of the Buzzard Creek craters.  Whether the craters are tectonically linked to the Aleutian subduction zone is not clear.\"","NameOrigin":"The Buzzard Creek craters are informally named after the nearby Buzzard Creek. Buzzard Creek was named by early prospectors, and reported as a place name in 1907 (Brooks, Orth, 1971)."},{"VolcanoId":"ak242","Vnum":315010,"Volcano":"Sanford","OfficialName":"Mount Sanford","ParentVolcanoId":"ak242","ParentVolcano":"Sanford","AgeClass":"Pleistocene","AgeSource":"Richter and others (2006) place Mt. Sanford's age from 0.9 to 0.5 Ma.","Composition":"andesite","IsMonitored":false,"VolcanoType":"Shield volcano?","NvewsThreat":null,"Description":"   From Wood and Kienle (1990): \"Mount Sanford, a very large dissected shield with an impressive bulbous top, is the highest volcano in the Wrangell volcanic field.  Most of the upper part (\u003e2,500 m) is covered by perennial snow and ice, making study and observation difficult.  The principal \"window\" through the ice cap is the great amphitheater at the head of the Sanford Glacier which rises more than 2,400 m in less than 1,500 m.  Data from unpublished geologic mapping around the volcano's base, and fly-by observations of the great amphitheater and other cirques, indicate that the upper part of Mount Sanford is a young feature, * * * that developed on a base of at least three coalescing andesitic shield volcanoes, referred to as the north, west, and south Sanford eruptive centers.  The centers may contain shallow dacite and andesite intrusives, dike complexes, vent deposits, and may be the locus of linear rift vents; all centers are marked by topographic highs.\"","NameOrigin":"Mount Sanford was named in 1885 by Lieutenant Allen, for the Sanford family; his great-grandfather was Reuben Sanford (Orth, 1971)."},{"VolcanoId":"ak109","Vnum":315021,"Volcano":"Gordon","OfficialName":"Mount Gordon","ParentVolcanoId":"ak109","ParentVolcano":"Gordon","AgeClass":"SuspPleist","AgeSource":"Richter and others (2006) believe Gordon is Pleistocene in age.","Composition":"mafic","IsMonitored":false,"VolcanoType":"Cinder cones","NvewsThreat":null,"Description":"   From Miller and Richter (1994): \"This is the largest of the young (\u003c1.5 Ma) basalt-basaltic andesite cinder cones that are common in the northwestern part of the Wrangell volcanic field.  The cone of Mt. Gordon, about 5 km in diameter and 600 m high above its base of older Wrangell lava, also erupted a significant volume of basaltic lava flows (Richter and Smith, 1976).\"","NameOrigin":"Mount Gordon was named for a prospector who was in the area in 1899. F.C. Schrader, U.S. Geological Survey, reported the name in 1903 (Orth, 1971)."},{"VolcanoId":"ak82","Vnum":315050,"Volcano":"Duncan Canal volcanic field","OfficialName":null,"ParentVolcanoId":"ak82","ParentVolcano":"Duncan Canal volcanic field","AgeClass":"SuspHolo","AgeSource":"Brew and others (1985) suspected Duncan Canal volcanics might be Holocene in age, due to fresh morphology, but Brew and others (1996) map calls them Quaternary or Tertiary.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Volcanic field","NvewsThreat":"Very Low Threat","Description":"   From Wood and Kienle (1990): \"Olivine-bearing tholeiitic basalt with average K-content, together with minor sodic alkalic basalts, overlie volcanic-rich gravel and glacial till along the southern coast of Kupreanof Island west of Duncan Canal.  The flows are recognized in the field by their conspicuous fresh-appearing pahoehoe and aa surfaces.  Two probable vents lie within the Mesozoic and Paleozoic rocks of the Duncan Canal fault zone north of the main exposures; the northern one contains scattered peridotite nodules.  The relations of the main exposures to the subjacent middle Tertiary volcanic rocks of the Kuiu-Etolin volcanicplutonic belt are not clear at the western end of the field because the Holocene basalt is difficult to differentiate from the adjacent older basalt.\"","NameOrigin":"\"Duncan Canal volcanic field\", as applied to the group of volcanic vents near the Duncan Canal waterway, is an informal name."},{"VolcanoId":"ak284","Vnum":315060,"Volcano":"Tlevak Strait volcanic field","OfficialName":null,"ParentVolcanoId":"ak284","ParentVolcano":"Tlevak Strait volcanic field","AgeClass":"SuspHolo","AgeSource":"Although Eberlein and others (1983) suspect Quaternary or Holocene age for the Tlevak Strait-Suemez Island volcanics, Brew and others (1996) map them as Quaternary-Tertiary.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Low gradient lava flows","NvewsThreat":"Very Low Threat","Description":"   From Wood and Kienle (1990): \"Flat-lying sodic alkalic olivine basalt flows with fresh pahoehoe surfaces occur in the vicinity of Tlevak Strait west of Prince of Wales Island, at Trocadero Bay on Suemez Island, and in valleys on northern Dall Island.  The outcrop areas are indicated by Qb on the map [Eberlein and others, 1983].\"","NameOrigin":"\"Tlevak Strait\", as applied to the group of volcanic vents near Tlevak Strait waterway, is an informal name."},{"VolcanoId":"ak12","Vnum":null,"Volcano":"Andrew Bay volcano","OfficialName":null,"ParentVolcanoId":"ak12","ParentVolcano":"Andrew Bay volcano","AgeClass":"","AgeSource":"Coats (1956) suspected Andrew Bay was Tertiary. (Delete from record?)","Composition":"andesite","IsMonitored":false,"VolcanoType":"Volcano remnant","NvewsThreat":null,"Description":"   From Wood and Kienle (1990): \"Adak is a large Tertiary island in the central Aleutians with a small (~40 cubic km) volcanic center at its northern extremity.  Kanaga lies to the west and Great Sitkin to the east.  Because of its easy access, Adak is certainly the most frequently visited and sampled island in the Aleutians.  Andrew Bay (~350 m, oldest), Mount Moffet (1,200 m), and Mount Adagdak (650 m) volcanoes have produced essentially all the Recent volcanic material.  Only the erosional vestiges of Andrew Bay volcano remain (now filled by Andrew Bay and Lake); it was apparently obliterated by caldera formation, encroachment of the sea, and glaciation.  Heavily glaciated, Mount Moffet consists of principally of thick andesite flows, flank domes, and a substantial parasitic cone of many thin basalt flows.  The scoriaceous, blocky dome on the outward south flank of Mount Moffet may be one of the youngest volcanic features of this center.  Mount Adagdak is a model composite cone with a distinct lower shield of one or two basalt flows and interbedded scoria.  At ~350 m the small stratovolcano begins, consisting mainly of volcaniclastic debris and an occasionally thin, fragmentary andesitic flow.  The summit crater, with a well-defined south rim, is occupied by a hornblende andesite plug; in places it has vertical, smooth walls peppered with indigenous xenoliths.  At one time this plug may have been partly a Pelean spine, large blocks of which are scattered across the shield.  A northwesterly directed explosion and ash flow may have strongly breached the summit crater prior to the vent-filling event.  A late stage basaltic dome lies on the southeast flank.\r\n   \"Although Moffet and Adagdak are certainly volcanoes, when compared to large Aleutian volcanoes, both vents represent small, almost futile outpourings.  This is perhaps reflected in the heterogeneous nature and composition of the erupted materials.  Mafic, olivine-rich xenolithic material is common in a thick andesite flow on the north shore of Mount Moffet, and also in an apparently phreatic vent on the west shield of Mount Adagdak; gabbroic and dioritic xenoliths are found along the bouldery beach north of Mount Adagdak.\"","NameOrigin":"\"Andrew Bay volcano\" is an informal name applied to the remnants of a volcano at Andrew Bay. The name Andrew Bay comes from a translation of \"Z[aliv] Andreyana,\" published in 1852 by Captain Tebenkov (Orth, 1971)."},{"VolcanoId":"ak11","Vnum":null,"Volcano":"Ancient Mount Kanaton","OfficialName":null,"ParentVolcanoId":"ak144","ParentVolcano":"Kanaga","AgeClass":"SuspPleist","AgeSource":"Coats (1956) believes this volcano is Tertiary to Quaternary.","Composition":"basaltic_andesite","IsMonitored":false,"VolcanoType":"Pleistocene caldera","NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak214","Vnum":null,"Volcano":"Pogromni","OfficialName":"Pogromni Volcano","ParentVolcanoId":"ak322","ParentVolcano":"Westdahl","AgeClass":"Pleistocene","AgeSource":"Calvert and others (2005) obtained a 40Ar/39Ar age of 76+/-25 ky for a sample from Pogromni.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Stratovolcano","NvewsThreat":null,"Description":"   From Wood and Kienle (1990): \"Pogromni volcano is a steep-sided stratovolcano on the southwest end of Unimak Island.  All of the lavas analyzed from Pogromni are tholeiitic basalt.  A single glacier is found on Pogromni.  Outcrops in the glacially scoured walls of Pogromni suggest a caldera collapse was followed by building of the present cone.  Another peak (Pogromni's Sister, 1,230 m) may be a remnant of this older vent.\r\n   \"Five cinder cones are aligned with Pogromni volcano along a northwest-southeast trend.  The monogenetic cones are 50-100 m high and are strongly oxidized on the surface.\r\n   \"Pogromni volcano is little know.  Reconnaissance petrologic studies report a few analyses from the satellitic cinder cones.\"","NameOrigin":"According to the 1883 Coast Pilot, this volcano's name was published by Lutke in 1836 as \"Pogromnoi Volcan.\" Russian Hydrographic Department Chart 1379 (1847) shows it as \"Sopka Pogromnaya,\" meaning \"Desolation Peak.\" Its Aleut name, according to Grewingk (1850) is \"Kugidach Jagutscha\" (Orth, 1971)."},{"VolcanoId":"ak198","Vnum":null,"Volcano":"Nelson Island","OfficialName":"Nelson Island","ParentVolcanoId":"ak198","ParentVolcano":"Nelson Island","AgeClass":"SuspPleist","AgeSource":"Moll-Stalcup, in Wood and Kienle (1990), states that Nelson Island volcanics are perhaps late Tertiary rather than Quaternary, although Ingariak Hills, Tern Mountain, Cheching Mounta, and benchmark Kinia appear younger.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Lava flow field?","NvewsThreat":null,"Description":"   From Wood and Kienle (1990): \"Reconnaissance geologic mapping of Nelson Island revealed basaltic lava flows ~30 m thick dipping gently eastward.  The topography of the island suggests it is highly dissected and probably late Tertiary rather than Quaternary in age.  Younger looking isolated cones are evident to the south at Ingariak Hills, Tern Mountain, Cheching Mountain, and benchmark Kinia.\"","NameOrigin":"Nelson Island was named in 1880 by Henry Gannet, for Edward William Nelson, who spent about five years in this area as an observer for the U.S. Signal Service and a collector for the Smithsonian Institution (Orth, 1971)."},{"VolcanoId":"ak172","Vnum":null,"Volcano":"Koyuk-Buckland volcanics","OfficialName":null,"ParentVolcanoId":"ak172","ParentVolcano":"Koyuk-Buckland volcanics","AgeClass":"SuspPleist","AgeSource":"Patton and Miller (1968) label the Koyuk-Buckland volcanics as Quaternary or Tertiary in age.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Monogenetic volcano field","NvewsThreat":null,"Description":"   From Wood and Kienle (1990): \"The Koyuk-Buckland monogenetic volcano field is the largest basalt field in Alaska, and among the least known.  It is mostly contained within the Candle quadrangle.  The field consists of basalt flows, with local aggregate thickness of 150 m, which have erupted from ~46 cinder cones and small shield volcanoes.  Most of the basalts are flat-lying, but some have been gently folded.  The age of the basalts is unknown, but they are thought to be correlative with the Imuruk basalt field 100 km to the west.  The composition of the field is also unknown, but the presence of ultramafic nodules suggests that at least some flows are alkaline.\"","NameOrigin":"\"Koyuk-Buckland volcanics\" is an informal name, derived from the names of nearby villages."},{"VolcanoId":"ak241","Vnum":null,"Volcano":"Sajaka Two","OfficialName":"Cape Sajaka","ParentVolcanoId":"ak280","ParentVolcano":"Tanaga","AgeClass":"Holocene","AgeSource":"Coombs and others (2007) report radiometric age dates at Sajaka from 5,000 years ago to the present.","Composition":"unknown","IsMonitored":false,"VolcanoType":"Stratocone","NvewsThreat":null,"Description":null,"NameOrigin":"The volcanic cone \"Sajaka\" is informally called after Cape Sajaka, which it forms. Cape Sajaka was named \"Cape Sajaga\" by the North Pacific Exploring Expedition of 1855. Captain Tebenkob (1852) called \"M[ys] N.W.\" or \"Northwest Cape.\" The adopted form \"Cape Sajaka\" was published in the 1944 Aleutian Coast Pilot (Orth, 1971)."},{"VolcanoId":"ak286","Vnum":null,"Volcano":"Togiak volcanics","OfficialName":null,"ParentVolcanoId":"ak286","ParentVolcano":"Togiak volcanics","AgeClass":"Pleistocene","AgeSource":"Hoare and Coonrad (1980) report a single K-Ar date of 0.76 Ma for the Togiak volcanics.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Lava field","NvewsThreat":null,"Description":"   From Wood and Kienle (1990): \"The Togiak volcanics are a late Pleistocene set of thin (\u003c20 m thick) lava flows underlying ~450 square km of the Togiak River valley in southwest Alaska.  The flows are largely covered by glacial deposits, but excellent exposures occur in sea cliffs on Togiak Bay and along cutbanks of various rivers.  Three probable vents have been detected; the most interesting is a 300-m-high tuya or subglacial volcano.  Togiak Tuya is 6 km long x 2.5 km wide and is elongated parallel to regional faults and the flow of glacial ice.  The elongated shape suggests formation in an actively flowing glacier; most other tuyas apparently formed in stagnant ice.  Sideromelane tuff and pillow basalts make up the main mass of the tuya, but the top 40-50 m are subaerial flows, formed where the volcano grew above the glacier.  It has been speculated that the tuya may have formed during a glacial period ~39,000 yr ago, and a single K-Ar age of 0.76 Ma is recorded for the underlying basalts, all of which have normal magnetic polarity.  The lavas are confined to a graben between northeast-trending faults, and appear to have erupted from vents along the faults.\"","NameOrigin":"\"Togiak volcanics\" is an informal name. The volcanics  are located near Togiak village and the Togiak River."},{"VolcanoId":"ak39","Vnum":null,"Volcano":"Capital","OfficialName":"Capital Mountain","ParentVolcanoId":"ak39","ParentVolcano":"Capital","AgeClass":"Pleistocene","AgeSource":"Richter and others (2006) show Capital Mountain as being 1 Ma.","Composition":"andesite","IsMonitored":false,"VolcanoType":"Shield volcano","NvewsThreat":null,"Description":"   From Wood and Kienle (1990): \"Capital Mountain is a relatively small andesitic shield volcano with a roughly circular summit caldera 4 km in diameter.  The shield consists chiefly of lava flows and subordinate volcaniclastic rocks that dip 3 to 25 degrees away from the summit area.  The caldera, apparently of non-explosive origin, is filled with thick, flat-lying flows.  Talus, flow breccias, and pillow lavas occur locally between the caldera wall and intracaldera flows.  A prominent andesite plug, 100 m high, marks the general center of an area of post-caldera-fill activity and is the locus of a spectacular radial dike swarm.  Shield and intracaldera lavas are chiefly hypersthene andesite, but shield lavas range in composition from basalt to dacite.  Dikes are also chiefly andesite; one prominent rhyolite dike originating from a small rhyolite laccolith extends almost completely across the volcano.\"","NameOrigin":"The name Capital Mountain was recorded by T.G. Gerdine as a local name (Mendenhall, 1905; Orth, 1971)."},{"VolcanoId":"ak81","Vnum":null,"Volcano":"Drum","OfficialName":"Mount Drum","ParentVolcanoId":"ak81","ParentVolcano":"Drum","AgeClass":"Pleistocene","AgeSource":"Richter and others (2006) show Drum as being from 0.6 to 0.2 Ma.","Composition":"mixed","IsMonitored":false,"VolcanoType":"Stratovolcano","NvewsThreat":null,"Description":"   From Wood and Kienle (1990): \"Mount Drum, the westernmost volcano in the Wrangell volcanic field, was formed between ~0.65 and 0.24 Ma during at least two cycles of cone-building and ring-dome extrusion.  The first cycle began with the construction of a cone consisting chiefly of andesite and dacite lava flows, breccias, lahars, and tuffs, and culminated with the emplacement of a series of rhyolite ring domes around the cone's southeast flank.  The second cycle of activity, following without an apparent time break, continued to build the cone but with more dacitic flows and fewer pyroclastic and volcaniclastic deposits.  This stage was followed by the emplacement of at least nine dacitic domes that lie on 270 degrees of arc, crudely defining a circle ~12-13 km in diameter centered approximately at the present summit of Mount Drum.  The rhyodacite dome of Snider Peak and its massive dacite flows erupted late in the second cycle, probably marking the end of major constructive activity.  Following the second cycle, paroxysmal explosive activity, probably from the central vent area, destroyed the south half of the stratovolcano and deposited ~7 cubic km of hot and cold avalanche debris over an area \u003e200 square km.\"","NameOrigin":"Mount Drum was named by Lt. Allen in 1885, for Adj. General Richard Coulter Drum, 1825-1909, who entered the army in 1846, served in the Mexican War, participated in an expedition against the Sioux Indians in 1856, and became a Brigadier General during the Civil War (Orth, 1971)."},{"VolcanoId":"ak133","Vnum":null,"Volcano":"Ingrisarak Mtn","OfficialName":"Ingrisarak Mountain","ParentVolcanoId":"ak133","ParentVolcano":"Ingrisarak Mtn","AgeClass":"SuspPleist","AgeSource":"Hoare and Condon (1968) believe Ingrisarak Mountain is Quaternary in age.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Cinder cone","NvewsThreat":null,"Description":"   From Wood and Kienle (1990): \"Ingrisarak Mountain is a volcanic vent, composed entirely of red and black basalt scoria.  It is 10 x 11 km in size.\" From Hoare and Condon, 1968: \"Basalt (Qb) forms Ingrisarak Mountain, a volcanic vent, and also crops out near the eastern edge of the quadrangle on the flank of a similar vent in the adjoining Marshall quadrangle. Red and black fragments of basalt scoria are widespread in both areas, but no rock was found in place. The fragments have not moved far; they are angular, unweathered, and commonly show ropy flow features. The basalt consists of scattered phenocrysts of pyroxene and olivine in a fine-grained matrix. The basalt is assigned a Quaternary age because it is very fresh appearing and because the volcanic vents, although modified, are still physiographically expressed. Paleomagnetic measurements on oriented specimens from similar volcanic vents in the adjoning Marshall and Kwiguk quadrangles show that the basalt is normally magnetized. The physiographic expression and normal magnetic polarity suggests that the basalt was extruded during the latest (Brunhes) normal polarity epoch (Cox and others, 1964, 1965). Recent studies (Dalrymple and others, 1965, Doell and othres, 1966) indicate that the Brunhes epoch began about 0.7 million years ago.\"","NameOrigin":"\"Ingrisarak Mountain\" is a Yup'ik name reported in 1951 by the U.S. Coast and Geodetic Survey (Orth, 1971)."},{"VolcanoId":"ak84","Vnum":null,"Volcano":"East Cape","OfficialName":"East Cape Volcano","ParentVolcanoId":"ak34","ParentVolcano":"Buldir","AgeClass":"SuspHolo","AgeSource":"Smith and Shaw (1975) suggest a Holocene age for Buldir, although Coats (1956) thought Pleistocene.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Stratovolcano","NvewsThreat":null,"Description":"   From Wood and Kienle (1990): \"Buldir Island is the westernmost volcanic center of the present Pleistocene to Recent Aleutian volcanic front.  The next westward subaerial volcanism is in Kamchatka.  Buldir is a small (~2 cubic km), isolated, and mountainous island consisting of two volcanoes, the older of which is Buldir volcano and the younger East Cape volcano.  Although broadly of similar age, a significant lapse of time between their formation allowed considerable marine and subaerial erosion, the products of which fill the lowlands.  Buldir volcano, which once had a parasitic cone, consists of a few thin (3-m), olivine-bearing, high alumina basalt flows and much volcaniclastic debris.  East Cape volcano has two vents: the principal vent forms an eruptive cone cored by a late stage plug, whereas the secondary vent is a large flank dome of hornblende andesite.\r\n   \"Buldir Island is unusual in its restricted flora relative to neighboring islands, suggesting that it is comparatively young and not a fragment of a much older, larger subaerial island.  The once nearly extinct Aleutian goose (a lesser Canada goose) was rekindled from relict nestings on Buldir.\"","NameOrigin":"East Cape Volcano's name was reported by Coats (1953)."},{"VolcanoId":"ak298","Vnum":null,"Volcano":"Ungulungwak Hill-Ingrichuak Hill","OfficialName":null,"ParentVolcanoId":"ak298","ParentVolcano":"Ungulungwak Hill-Ingrichuak Hill","AgeClass":"SuspPleist","AgeSource":"Hoare and Condon (1971) assign Ungulungwak Hill - Ingrichuak Hill volcanics a Quaternary age, based on morphology and paleomagnetic measurements.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Lava shield field","NvewsThreat":null,"Description":"   From Wood and Kienle (1990): \"This field consists of numerous lava flows 1.5 to 4.5 m thick, and at least five low shield volcanoes from 30 to 188 m high (four are 166 to 188 m high) and 5 to 11 km across.  Although the volcanoes are modified by erosion and widely covered with silt, they are inferred to be Quaternary in age based on their physiographic expression.  The volcanoes consist of vesicular and scoriaceous olivine basalt.\"","NameOrigin":"\"Ungulungwak Hill - Ingrichuak Hill\" is an informal name, after the principal peaks in the volcanic field, Ungulungwak Hill and Ingrichuak Hill, although there are at least five shield volcanoes in the field. \"Ungulungwak\" and \"Ingrichuak\" are both local Native names, reported in the late 1800s."},{"VolcanoId":"ak166","Vnum":null,"Volcano":"Kochilagok Hill","OfficialName":null,"ParentVolcanoId":"ak166","ParentVolcano":"Kochilagok Hill","AgeClass":"SuspPleist","AgeSource":"Hoare and Condon (1971) assign Kochilagok Hill volcanics a Quaternary age, based on morphology and paleomagnetic measurements.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Cinder cone and lava flow","NvewsThreat":null,"Description":"   From Wood and Kienle (1990): \"A low vent and associated flow occur at Kochilagok Hill.  Geologic maps designate the volcano as chiefly basalt scoria.\"","NameOrigin":"\"Kochilagok Hill\" is a Yup'ik name that refers to the \"crake\" (lesser sandhill crane, Grus canadensis canadensis) and reported by the U.S. Coast and Geodetic Survey in 1949. Gabrielson and Lincoln (1959) report that the name means \"color body, red\" (Orth, 1971)."},{"VolcanoId":"ak205","Vnum":null,"Volcano":"Nushkolik Mountain volcanic field","OfficialName":null,"ParentVolcanoId":"ak205","ParentVolcano":"Nushkolik Mountain volcanic field","AgeClass":"SuspPleist","AgeSource":"Hoare and Condon (1971) assign Nushkolik Mountain volcanics a Quaternary age, based on morphology and paleomagnetic measurements.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Shield volcano?","NvewsThreat":null,"Description":"   Nushkolik Mountain volcanic field is a shield volcano (?), 8 to 195 m high, measuring 12 x 14 km, with no historic activity.  Volcanic rocks are of olivine basalt composition (Wood and Kienle, 1990).","NameOrigin":"\"Nushkolik Mountain volcanic field\" is an informal name, after Nushkolik Mountain, which is part of the field. Nushkolik Mountain was reported as a Yup'ik name by the U.S. Coast and Geodetic Survey in 1951 (Orth, 1971)."},{"VolcanoId":"ak45","Vnum":null,"Volcano":"Cerberus, Mt","OfficialName":"Mount Cerberus","ParentVolcanoId":"ak288","ParentVolcano":"Trident","AgeClass":"Pleistocene","AgeSource":"Hildreth and others (2003) give a K-Ar age of 114 +/- 46 ka for Mount Cerberus.","Composition":"dacite","IsMonitored":false,"VolcanoType":"Lava dome","NvewsThreat":null,"Description":"   From Wood and Kienle (1990): \"Falling Mountain and Mount Cerberus are the twin domes of pyroxene dacite (64% SiO2) that frame the entrance to Katmai Pass.  They are similar in volume (each 0.25 cubic km), composition, lithology, and weathering.  Although undated, they are thought to be of early Holocene age because their carapaces are degraded but not significantly glaciated.  The two domes are compositionally similar (but not identical) to 1912 dacite.  Together with the rhyolitic Novarupta dome, they define a 3-km-long line parallel to, but 4 km behind, the volcanic front.\"","NameOrigin":"R.F. Griggs named Mount Cerberus in 1917, writing that it was descriptive of Mount Cerberus \"being the [three-headed] watchdog guarding Hades [Valley of Ten Thousand Smokes]\" (Orth, 1971)."},{"VolcanoId":"ak96","Vnum":null,"Volcano":"Falling Mtn","OfficialName":"Falling Mountain","ParentVolcanoId":"ak288","ParentVolcano":"Trident","AgeClass":"Pleistocene","AgeSource":"Hildreth and others (2003) give a K-Ar age of 70 +/- 8 ka for Falling Mountain.","Composition":"dacite","IsMonitored":false,"VolcanoType":"Dome","NvewsThreat":null,"Description":"   From Wood and Kienle (1990): \"Falling Mountain and Mount Cerberus are the twin domes of pyroxene dacite (64% SiO2) that frame the entrance to Katmai Pass.  They are similar in volume (each 0.25 cubic km), composition, lithology, and weathering.  Although undated, they are thought to be of early Holocene age because their carapaces are degraded but not significantly glaciated.  The two domes are compositionally similar (but not identical) to 1912 dacite.  Together with the rhyolitic Novarupta dome, they define a 3-km-long line parallel to, but 4 km behind, the volcanic front.\"","NameOrigin":"Falling Mountain was named in 1917 by R.F. Griggs, because of the freqent avalanches down its flanks (Orth, 1971)."},{"VolcanoId":"ak148","Vnum":null,"Volcano":"Kejulik","OfficialName":null,"ParentVolcanoId":"ak148","ParentVolcano":"Kejulik","AgeClass":"SuspPleist","AgeSource":"Riehle and others (1993) label Kejulik as late Tertiary or Pleistocene.","Composition":"andesite","IsMonitored":false,"VolcanoType":"Dissected stratovolcano?","NvewsThreat":null,"Description":"   From Wood and Kienle (1990): \"Kejulik is a remnant of a volcano in the southwestern Kejulik Mountains. A radial system of glacially carved valleys surrounds the present topographic high.  Extensive glacial erosion has removed most of the lavas, but remnants of lava flows and lahars are preserved on the radial ridges.  A series of dikes intrudes the near-horizontal Mesozoic sedimentary rocks beneath the flows.  A zone of hydrothermally altered breccia near the present summit marks the former vent of the volcano.\r\n   \"Little information has been published on Kejulik.  All of the analyzed samples are porphyritic andesites.  No recent activity is known.\"","NameOrigin":"\"Kejulik volcano\" is an informal name, derived from the surrounding Kejulik Mountains."},{"VolcanoId":"ak279","Vnum":null,"Volcano":"Tanada Peak","OfficialName":null,"ParentVolcanoId":"ak279","ParentVolcano":"Tanada Peak","AgeClass":"Pleistocene","AgeSource":"Richter and others (2006) provide dates of 1.8 to 0.9 Ma for Tanada Peak.","Composition":"andesite","IsMonitored":false,"VolcanoType":"Shield volcano","NvewsThreat":null,"Description":"   From Wood and Kienle (1990): \"Tanada Peak is the erosional remnant of an andesitic shield volcano that contained an oval-shaped summit caldera , ~8 km long x 6 km wide.  Very little of the original shield, which covered more than 400 square km, remains; rugged Tanada Peak, highest point on the volcano, is composed entirely of flat-lying intracaldera? flows.  Tanada was built on a thick sequence of andesitic flows, flow breccias, and laharic deposits probably of late Pliocene to early Pleistocene age.  A riftlike chain of younger basalt and basaltic andesite cones mantles part of the northern flank of the shield, and much of the volcano's southern flank is covered by flows and pyroclastic deposits from younger unmapped eruptive centers.\r\n   \"Tanada shield lavas consist chiefly of thin (\u003c10 m) andesite flows that dip 1 to 20 degrees away from the summit area.  The summit caldera, of apparent non-explosive origin, is filled with \u003e900 m of massive, flat-lying andesite flows and dacitic agglutinates.  The dacitic rocks are restricted to the uppermost part of the caldera fill, suggesting a temporally related change in magma chemistry.  A few post-caldera dikes are either andesitic or dacitic in composition.  The caldera wall dips 20 to 50 degrees inward and is mantled locally by thin pyroclastic beds and rubbly breccias.  Most of the remaining exposed wall is composed of the older andesite sequence; only on the east side of the volcano, and locally elsewhere, are shield lavas still present in the wall.\"","NameOrigin":"Tanada Peak was named in 1902 by D.C. Witherspoon, for nearby Tanada Lake. \"Tanada Lake\" is a Native name reported by W.J. Peters in 1899 (Orth, 1971)."},{"VolcanoId":"ak138","Vnum":null,"Volcano":"Jarvis","OfficialName":"Mount Jarvis","ParentVolcanoId":"ak138","ParentVolcano":"Jarvis","AgeClass":"Pleistocene","AgeSource":"Richter and others (2006) provide dates of 1.7 - 1.0 Ma for Mount Jarvis.","Composition":"andesite","IsMonitored":false,"VolcanoType":"Eroded stratocone","NvewsThreat":null,"Description":"   From Miller and Richter (1994): \"This mountain is the high point of a slightly curvilinear, north-trending, 10-km-long, 4,000-m-high ridge.  The snow- and ice-covered ridge is composed of a thick sequence of dacitic and andesitic lava flows and capped by either a massive dacite flow or by a series of smaller dacite domes.  One K-Ar age on basal (?) Jarvis flows suggests an age of about 1.6 Ma (Richter and Smith, 1976).\"","NameOrigin":"Mount Jarvis was named in 1903 by F.C. Schrader, for Captain D.H. Jarvis, who spent several years in Alaska (Orth, 1971)."},{"VolcanoId":"ak255","Vnum":null,"Volcano":"Skookum Creek","OfficialName":null,"ParentVolcanoId":"ak255","ParentVolcano":"Skookum Creek","AgeClass":"Pleistocene","AgeSource":"Richter and others (2006) provide dates of 3.2-2.0 Ma (from Miller and Richter, 1997 and Lowe and others, 1982) for the Skookum Creek volcanic center, making it possibly just barely Pleistocene.","Composition":"mixed","IsMonitored":false,"VolcanoType":"Andesite and basaltic andesite flows; dacite and rhyolite domes","NvewsThreat":null,"Description":"   From Miller and Richter (1994): \"The Skookum Creek eruptive center is an erosionally dissected complex that may, in part, be as young as Quaternary.  It consists principally of a series of rhyolite, rhyodacite, and andesite domes and their associated pyroclastic deposits, with an age of about 3.7 Ma, and an extensive sequence of relatively flat-lying andesite flows, some of which have been dated at 2.8 Ma (Lowe and others, 1982).  Both the domes and the flows are intruded by a few rhyodacite and andesitic dikes that appear to originate from a rhyodacite dome near the center of the complex.  Relations between the volcanic units of the complex suggest that the flat-lying flows fill a caldera that is defined by the crude arcuate alignment of the domes.\"","NameOrigin":"\"Skookum Creek eruptive center\" is an informal name, after the nearby Skookum Creek.  \"Skookum\" is a Chinook jargon word meaning \"strong, brave, bold, or best.\""},{"VolcanoId":"ak181","Vnum":null,"Volcano":"Little Pavlof","OfficialName":"Little Pavlof","ParentVolcanoId":"ak210","ParentVolcano":"Pavlof","AgeClass":"SuspHolo","AgeSource":"Waythomas and others (2006) believe that Little Pavlof has been active within the last 10,000 years.","Composition":"mafic","IsMonitored":false,"VolcanoType":"Parasitic polygenetic cone","NvewsThreat":null,"Description":null,"NameOrigin":"The U.S. Geological Survey named Little Pavlof in 1929 (Orth, 1971)."},{"VolcanoId":"ak78","Vnum":null,"Volcano":"Double Crater","OfficialName":null,"ParentVolcanoId":"ak93","ParentVolcano":"Emmons Lake Volcanic Center","AgeClass":"SuspHolo","AgeSource":"Waythomas and others (2006) suspect Double Crater has had Holocene eruptions, based on vent morphology.","Composition":"andesite","IsMonitored":false,"VolcanoType":"Stratovolcano","NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak261","Vnum":null,"Volcano":"St. George volcanic field","OfficialName":null,"ParentVolcanoId":"ak261","ParentVolcano":"St. George volcanic field","AgeClass":"Pleistocene","AgeSource":"Mukasa and other (2007) provide 40Ar/39Ar age dates of 2.5-1.5 Ma for St. George volcanics.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Monogenetic volcano field","NvewsThreat":null,"Description":"   From Wood and Kienle (1990): \"St. George is the second largest of the Pribilof Islands, a group of late Tertiary and Quaternary volcanic piles on the western edge of the Bering Sea shelf.  The volcanic rocks on St. George are Pliocene and early Pleistocene in age and are interbedded with marine sand and gravel, glacially derived sediments, frost breccia, and wind-blown sediments.  Along the southeastern coast, the St. George volcanic field has an exposed basement of serpentinized peridotite intruded by quartz diorite.  The lavas on St. George are older than those on nearby St. Paul, and the original volcanic topography has been subdued by weathering and later redefined by faulting, uplift, and glaciation.  Vestiges of cinder cones, with filled craters and slopes reduced by frost and mass-wasting processes, occur as flat-topped or domical hillocks.  Apparently alternating lava flows and pyroclastic eruptions in the eroded volcanic cones are actually evidence of much fountaining, which produced near-vent pumice interbedded with some flows in one eruptive event.\r\n   \"Sea cliffs provide the best exposures of the products of repeated eruptions; for example, the cliff at Tolstoi Point on the eastern tip of St. George is made up of seven flows as much as 7.6 m thick, with associated pyroclastic layers.  Similar to those on St. Paul Island, the St. George lavas consist of alkali olivine basalt and basanite, but the St. George samples and those from submarine dredge hauls near St. George have a broader range in SiO2 and include hypersthene-normative as well as nepheline-normative chemistries.  Mafic inclusions are common, and some flows contain granitic inclusions.  Many flows display a patchy zeolitization, which may have resulted from alteration during cooling shortly after emplacement.  Several flows that erupted during high sea-level episodes display thick and extensive pillow breccias and palagonite tuff sequences.\"","NameOrigin":"\"St. George volcanic field\" is an informal name, after Saint George Island, which is covered by the volcanic field. Saint George Island was \"discovered\" and named by G.G. Pribilov in 1786. He named it after his vessel, the Sveti Georgiy (Orth, 1971)."},{"VolcanoId":"ak221","Vnum":null,"Volcano":"Prindle Volcano","OfficialName":"Prindle Volcano","ParentVolcanoId":"ak221","ParentVolcano":"Prindle Volcano","AgeClass":"Pleistocene","AgeSource":"Blondes and others (2007) provide a date of 176 +/- 16 ka for Prindle Volcano, using (U-Th)/He dating of zircons.  Andronikov and Mukasa (2010) obtained a 40Ar/39Ar age of 0.2 Ma +/- 0.06.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Cinder cone and lava flow","NvewsThreat":null,"Description":"      From Wood and Kienle (1990): \"Prindle volcano is a small isolated basaltic cone in the midst of the metamorphic and granitic terrane of the Yukon-Tanana upland, east-central Alaska.  The cone is ~900 to 1,000 m in diameter at its base and has as crater ~90 m deep, which is breached on the south.  A lava flow extends from the breached crater ~6.4 km to the southeast, where it turns southwest and continues an additional 4.8 km in a river valley.\r\n   \"The cone and lava flow are vesicular basanite, rich in phenocrystal and xenocrystal olivine as well as inclusions of peridotite ranging up to 13 cm in diameter.  Fragments of crystalline schists of the granulite facies with gneissose structure also occur as inclusions, but are less abundant than peridotite inclusions.\"\r\n   Blondes and others (2007) report an eruption age for Prindle of 176,000 years, +/- 16,000. Andronikov and Mukasa (2010) report a 40Ar/39Ar age of 200,000 years, +/- 60,000.","NameOrigin":"Waldo Smith, of the U.S. Geological Survey, named Prindle Volcano in 1926 for Louis Marcus Prindle, a U.S. Geological Survey geologist who published a photograph of the cone (Orth, 1971)."},{"VolcanoId":"ak303","Vnum":null,"Volcano":"Stepovak Bay 1","OfficialName":null,"ParentVolcanoId":"ak303","ParentVolcano":"Stepovak Bay 1","AgeClass":"Pleistocene","AgeSource":"Wilson (1989) obtained two K-Ar age dates for this volcano: 0.53 Ma and 0.4 Ma.","Composition":"andesite","IsMonitored":false,"VolcanoType":"Stratovolcano","NvewsThreat":"Low Threat","Description":"   This volcano is a member of the Stepovak Bay group.  From Wood and Kienle (1990): \"The Stepovak Bay group is a chain of five volcanoes at the southwest end of a N40 degrees E oriented linear segment of the Aleutian arc on the Alaska Peninsula.  This same segment includes the better known Veniaminof and Aniakchak calderas.  Three of the Stepovak Bay volcanoes [2, 4, and Kupreanof] have clearly had Holocene eruptions, resulting in three small debris flows filling late Pleistocene glacial valleys, and a small cinder cone and associated lava flow.  The other two volcanoes (1 and 3) do not show unmistakable evidence of Holocene activity.  They have ice-filled summit craters 500 m (1) and 300 m (3) in diameter that may be late Pleistocene age.  These volcanoes have contributed to extensive late Tertiary and Quaternary lava flows, some extending near sea level.\"","NameOrigin":"\"Stepovak Bay 1\" is an informal name, after the nearby Stepovak Bay. As there are four unnamed volcanoes in this vicinity, they have been given numbers 1-4."},{"VolcanoId":"ak304","Vnum":null,"Volcano":"Stepovak Bay 2","OfficialName":null,"ParentVolcanoId":"ak304","ParentVolcano":"Stepovak Bay 2","AgeClass":"Holocene","AgeSource":"Wilson (1989) states that this volcano has \"clearly had Holocene eruptions.\"","Composition":"andesite","IsMonitored":false,"VolcanoType":"Stratovolcano","NvewsThreat":"Low Threat","Description":"   This volcano is a member of the Stepovak Bay group.  From Wood and Kienle (1990): \"The Stepovak Bay group is a chain of five volcanoes at the southwest end of a N40 degrees E oriented linear segment of the Aleutian arc on the Alaska Peninsula.  This same segment includes the better known Veniaminof and Aniakchak calderas.  Three of the Stepovak Bay volcanoes [2, 4, and Kupreanof] have clearly had Holocene eruptions, resulting in three small debris flows filling late Pleistocene glacial valleys, and a small cinder cone and associated lava flow.  The other two volcanoes (1 and 3) do not show unmistakable evidence of Holocene activity.  They have ice-filled summit craters 500 m (1) and 300 m (3) in diameter that may be late Pleistocene age.  These volcanoes have contributed to extensive late Tertiary and Quaternary lava flows, some extending near sea level.\"","NameOrigin":"\"Stepovak Bay 2\" is an informal name, after the nearby Stepovak Bay. As there are four unnamed volcanoes in this vicinity, they have been given numbers 1-4."},{"VolcanoId":"ak306","Vnum":null,"Volcano":"Stepovak Bay 4","OfficialName":null,"ParentVolcanoId":"ak306","ParentVolcano":"Stepovak Bay 4","AgeClass":"Holocene","AgeSource":"Wilson (1989) states that this volcano has \"clearly had Holocene eruptions.\"","Composition":"andesite","IsMonitored":false,"VolcanoType":"Stratovolcano","NvewsThreat":"Low Threat","Description":"   This volcano is a member of the Stepovak Bay group.  From Wood and Kienle (1990): \"The Stepovak Bay group is a chain of five volcanoes at the southwest end of a N40 degrees E oriented linear segment of the Aleutian arc on the Alaska Peninsula.  This same segment includes the better known Veniaminof and Aniakchak calderas.  Three of the Stepovak Bay volcanoes [2, 4, and Kupreanof] have clearly had Holocene eruptions, resulting in three small debris flows filling late Pleistocene glacial valleys, and a small cinder cone and associated lava flow.  The other two volcanoes (1 and 3) do not show unmistakable evidence of Holocene activity.  They have ice-filled summit craters 500 m (1) and 300 m (3) in diameter that may be late Pleistocene age.  These volcanoes have contributed to extensive late Tertiary and Quaternary lava flows, some extending near sea level.\"","NameOrigin":"\"Stepovak Bay 4\" is an informal name, after the nearby Stepovak Bay. As there are four unnamed volcanoes in this vicinity, they have been given numbers 1-4."},{"VolcanoId":"ak150","Vnum":null,"Volcano":"Khvostof","OfficialName":"Khvostof Island","ParentVolcanoId":"ak73","ParentVolcano":"Davidof","AgeClass":"SuspHolo","AgeSource":"Smith and others (1978) suggest Holocene for Davidof.","Composition":"unknown","IsMonitored":false,"VolcanoType":"Caldera remnant","NvewsThreat":null,"Description":"   From Wood and Kienle (1990): \"Davidof, Khvostof, and nearby small islands Pyramid and Lopy rise 100 m above a submarine platform as the remnants of a collapsed caldera.  This 'Aleutian Krakatoa' is thought to have formed during the late Tertiary, but the volcano is essentially unstudied.  The islands are covered by vegetation; however lava flows can be recognized on aerial photographs.  Lavas and pyroclastic layers form the islands, and rocks on the northern part of Davidof and Lopy Island are intensely hydrothermally altered.\"","NameOrigin":"\"Khvostof Island\" was probably a Russian name given by Admiral von Krusenstern (1827), as \"Khwostov,\" for Nikolai Alexandrovich Khwostov, a Russian naval officer who explored Alaska in 1802-04 with G.I. Davidof. Captain Lutke (1836) applied the name \"Khvostoff ile\" to the entire group of islands that includes Khvostof Island (Orth, 1971)."},{"VolcanoId":"ak7","Vnum":null,"Volcano":"Alagogshak","OfficialName":null,"ParentVolcanoId":"ak7","ParentVolcano":"Alagogshak","AgeClass":"Pleistocene","AgeSource":"Hildreth and others (1999) report Pleistocene K-Ar ages for Alagogshak.","Composition":"andesite","IsMonitored":false,"VolcanoType":"Stratocone","NvewsThreat":null,"Description":"   From Hildreth and others (1999): \"Alagogshak volcano, a newly recognized volcanic-front stratovolcano on the Alaska Peninsula rangecrest, 15 km southwest of Katmai Pass, produced 10-18 km3 of andesite-dacite eruptive products during several episodes of activity in the middle and late Pleistocene. From a central vent marked by hydrothermal alteration and remnants of a cratered fragmental cone on the present-day drainage divide, glacially incised stacks of lava flows (57-66 percent SiO,) dip radially and extend 6-10 km in most directions. Lava flows that make up four ridge-capping outliers well west of the volcano may also have erupted there. The medium-K calcalkaline Alagogshak eruptive suite is compositionally varied, probably reflecting independent evolution of different magma batches supplied in several episodes spread intermittently over at least 600,000 years.\"","NameOrigin":"\"Alagogshak volcano\" is an informal name, applied to this feature by Wes Hildreth, Judy Fierstein, Martin Lanphere, and David Siems. The volcano's name is derived from nearby Alagogshak Creek. Alagogshak Creek is a Native name published by Griggs (1922), as \"Alagogshuk Creek\" (Orth, 1971)."},{"VolcanoId":"ak79","Vnum":null,"Volcano":"Double Glacier","OfficialName":null,"ParentVolcanoId":"ak79","ParentVolcano":"Double Glacier","AgeClass":"Pleistocene","AgeSource":"Reed and others (1992) report K-Ar ages of 600-900 ka for Double Glacier. The samples have age dates of 627 +/-24 ka, 763+/-17 ka, and 887+/-15 ka (Reed and others, 1992).","Composition":"andesite","IsMonitored":false,"VolcanoType":"Pleistocene dome remnant","NvewsThreat":null,"Description":"   From Reed and others (1992): \"The volcano, located some 175 km southwest of Anchorage, lies in the 94-km-long interval between Redoubt and Spurr volcanoes. * * * The Double Glacier Volcano is exposed as a 2.3-km-long, northwest-trending oval-shaped nunatak surrounded by the Double Glacier.  The highest part of the 1.67 km square nunatak is about 430 m above the glacier surface.  Although glacial erratics have not been found on the top of the nunatak, it seems likely that the nunatak was covered by ice during one or more of the major glacial events of the Cook Inlet region as described by Schmoll and Yehle (1986).\r\n   \"Nearby outcrops of basement rock apparently limit the maximum diameter of the volcano to about 3.5 km.  A rough estimate of the original volume of volcanic rocks, assuming a cylindrical shape with a diameter of 2.3-3.5 km and a height of 500 m above the present ice surface, is 2-4.8 cubic km.  The volume of a cone of the same dimensions would be about 07.-1.6 cubic km.  These volumes suggest that DGV is small in comparison to most other Quaternary volcanoes in the Cook Inlet segment which have volumes that range from 15 to 50 cubic km (Miller and Richter, 1994).\"","NameOrigin":"\"Double Glacier volcano\" is an informal name applied to the volcano near Double Glacier. The glacier's name was a local name reported by the U.S. Geological Survey in 1958, and so-called because the glacier is divided into two lobes."},{"VolcanoId":"ak48","Vnum":null,"Volcano":"Chetaslina Vent","OfficialName":null,"ParentVolcanoId":"ak326","ParentVolcano":"Wrangell","AgeClass":"Pleistocene","AgeSource":"1.6-0.8 Ma, Richter and others, 2006. (SIM 2877)","Composition":"mafic","IsMonitored":false,"VolcanoType":"Stratocone remnant underlying modern Mt. Wrangell","NvewsThreat":null,"Description":null,"NameOrigin":"\"Chetaslina Vent\" is an informal name applied to this volcano; it is named after the nearby Chetaslina Glacier.  \"Chetaslina\" is an Ahtna name meaning \"marmot river, obtained in 1898 by Captain W.R. Abercrombie, who spelled it \"Chestalina\" (Orth, 1971)."},{"VolcanoId":"ak145","Vnum":null,"Volcano":"Kanaton Ridge","OfficialName":"Kanaton Ridge","ParentVolcanoId":"ak144","ParentVolcano":"Kanaga","AgeClass":"SuspPleist","AgeSource":"Coats (1956) believes this volcano is Tertiary to Quaternary.","Composition":"basaltic_andesite","IsMonitored":false,"VolcanoType":null,"NvewsThreat":null,"Description":null,"NameOrigin":"Kanaton Ridge's name was published in 1951 on a U.S. Geological Survey map (Orth, 1971)."},{"VolcanoId":"ak99","Vnum":null,"Volcano":"Fire Island","OfficialName":"Fire Island","ParentVolcanoId":"ak29","ParentVolcano":"Bogoslof","AgeClass":"Historical","AgeSource":"Historical eruptions.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Eroded dome remnant","NvewsThreat":null,"Description":null,"NameOrigin":"Fire Island's name was published in 1943 by the U.S. Coast and Geodetic Survey, although it was previously called \"Old Bogoslof\" (Orth, 1971)."},{"VolcanoId":"ak164","Vnum":null,"Volcano":"Kliuchef","OfficialName":"Mount Kliuchef","ParentVolcanoId":"ak17","ParentVolcano":"Atka volcanic complex","AgeClass":"Historical","AgeSource":"Historical eruptions.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Satellite vent","NvewsThreat":null,"Description":null,"NameOrigin":"\"Mount Kliuchef\" was published on a 1952 U.S. Geological Survey map. This is a descriptive name, derived from the Russian \"Kliuchevskaia,\" meaning \"springs,\" applied because of the numerous warm springs on its west slope (Orth, 1971)."},{"VolcanoId":"ak171","Vnum":311161,"Volcano":"Korovin","OfficialName":"Korovin Volcano","ParentVolcanoId":"ak17","ParentVolcano":"Atka volcanic complex","AgeClass":"Historical","AgeSource":"Historical eruptions.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Stratovolcano","NvewsThreat":"High Threat","Description":"   From Miller and others (1998): \"The active volcano front runs through northern Atka Island which has been geologically mapped on a reconnaissance scale by Marsh (1990) who described the overall structure of the volcanic center as that of a broad central shield upon which a large stratocone (Atka volcano) had been built.  This cone was destroyed during caldera formation about 300,000 to 500,000 years ago.  Korovin, neighboring Kliuchef, and probably Konia are products of the latest stage of volcanic activity on the island, which began perhaps 100,000 years ago based on the degree of dissection (B. Marsh, written commun., 1982).\r\n   \"Korovin volcano is a stratovolcano, 1533 m high and almost 7 km in basal diameter, having two summit vents 0.6 km apart.  The northwestern summit vent is a symmetric cone with a small crater.  The southeastern summit vent is on the remnant of a cone with a steep-walled crater, about 1 km wide at the rim and at least several hundred meters deep.  Intercalated lava flows and pyroclastic rocks comprise the upper part of the crater wall, but the bottom one hundred meters or so are nearly vertical and apparently consist entirely of lava flows.  A turquoise green lake fills the lower part of the crater; the color suggests the occurrence of solfataric activity (Sekora, 1973).\r\n   \"The west side of Sarichef and east flank of Konia are extensively dissected; Konia has a relatively fresh cinder cone on its west flank.  Sarichef is most likely a satellite vent of the earlier Atka volcano as is Kliuchef which is located on the northern rim of the Atka caldera.  Korovin and Kliuchef are virtually undissected and are thus apparently of post-glacial age.  Hot springs and fumaroles occur on the south and west flanks of Mt. Kliuchef and near the head of a glacial valley 6 km southwest of Korovin volcano (Motyka and others, 1993).\"","NameOrigin":"Captain Lutke published the name \"Korovinskoi Volcano\" for \"Korovin Volcano\" in 1836 (Orth, 1971)."},{"VolcanoId":"ak243","Vnum":null,"Volcano":"Sarichef","OfficialName":"Sarichef Volcano","ParentVolcanoId":"ak17","ParentVolcano":"Atka volcanic complex","AgeClass":"SuspHolo","AgeSource":"Possible historical eruption, relatively undissected.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Satellite vent","NvewsThreat":null,"Description":null,"NameOrigin":"Coats published the name \"Sarichef Volcano\" for this feature in 1950 (Orth, 1971)."},{"VolcanoId":"ak167","Vnum":null,"Volcano":"Konia","OfficialName":null,"ParentVolcanoId":"ak17","ParentVolcano":"Atka volcanic complex","AgeClass":"SuspHolo","AgeSource":"Wood and Kienle (1990): Konia \"is as old as much of Korovin itself.\"","Composition":"basalt","IsMonitored":false,"VolcanoType":"Stratovolcano","NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak18","Vnum":null,"Volcano":"Atka caldera","OfficialName":null,"ParentVolcanoId":"ak17","ParentVolcano":"Atka volcanic complex","AgeClass":"Pleistocene","AgeSource":"Marsh, in Wood and Kienle (1990) believes Atka caldera formed 300,000 to 500,000 years ago.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Caldera","NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak128","Vnum":null,"Volcano":"Ingariak Hills","OfficialName":"Ingariak Hills","ParentVolcanoId":"ak198","ParentVolcano":"Nelson Island","AgeClass":"SuspPleist","AgeSource":"Moll-Stalcup, in Wood and Kienle (1990), states that Nelson Island volcanics are perhaps late Tertiary rather than Quaternary, although Ingariak Hills, Tern Mountain, Cheching Mounta, and benchmark Kinia appear younger.","Composition":"basalt","IsMonitored":false,"VolcanoType":null,"NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak281","Vnum":null,"Volcano":"Tern Mtn","OfficialName":"Tern Mountain","ParentVolcanoId":"ak198","ParentVolcano":"Nelson Island","AgeClass":"SuspPleist","AgeSource":"Moll-Stalcup, in Wood and Kienle (1990), states that Nelson Island volcanics are perhaps late Tertiary rather than Quaternary, although Ingariak Hills, Tern Mountain, Cheching Mounta, and benchmark Kinia appear younger.","Composition":"basalt","IsMonitored":false,"VolcanoType":null,"NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak47","Vnum":null,"Volcano":"Cheching Mtn","OfficialName":"Cheching Mountain","ParentVolcanoId":"ak198","ParentVolcano":"Nelson Island","AgeClass":"SuspPleist","AgeSource":"Moll-Stalcup, in Wood and Kienle (1990), states that Nelson Island volcanics are perhaps late Tertiary rather than Quaternary, although Ingariak Hills, Tern Mountain, Cheching Mounta, and benchmark Kinia appear younger.","Composition":"basalt","IsMonitored":false,"VolcanoType":null,"NvewsThreat":null,"Description":null,"NameOrigin":"\"Cheching Mountain\" is a Native name, reported in 1949 by the U.S. Coast and Geodetic Survey (Orth, 1971)."},{"VolcanoId":"ak159","Vnum":null,"Volcano":"Kinia, benchmark","OfficialName":null,"ParentVolcanoId":"ak198","ParentVolcano":"Nelson Island","AgeClass":"SuspPleist","AgeSource":"Moll-Stalcup, in Wood and Kienle (1990), states that Nelson Island volcanics are perhaps late Tertiary rather than Quaternary, although Ingariak Hills, Tern Mountain, Cheching Mounta, and benchmark Kinia appear younger.","Composition":"basalt","IsMonitored":false,"VolcanoType":null,"NvewsThreat":null,"Description":null,"NameOrigin":"The volcanic vent near the Kinia benchmark (near the Kinia River) is informally called \"Kinia, benchmark.\""},{"VolcanoId":"ak302","Vnum":null,"Volcano":"Vent Mtn","OfficialName":"Vent Mountain","ParentVolcanoId":"ak14","ParentVolcano":"Aniakchak","AgeClass":"Holocene","AgeSource":"Neal and others (2001) state that Vent Mountain is younger than the 3,500 y BP caldera at Aniakchak.","Composition":"dacite","IsMonitored":false,"VolcanoType":"Stratovolcano","NvewsThreat":null,"Description":null,"NameOrigin":"R.H. Sargent named Vent Mountain in 1923 (Orth, 1971)."},{"VolcanoId":"ak274","Vnum":null,"Volcano":"Surprise Lake","OfficialName":null,"ParentVolcanoId":"ak14","ParentVolcano":"Aniakchak","AgeClass":"Holocene","AgeSource":"Neal and others (2001) believe Surprise Lake had explosive eruptions 1,490 y BP.","Composition":"dacite","IsMonitored":false,"VolcanoType":"Intracaldera lake","NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak285","Vnum":null,"Volcano":"Togiak Tuya","OfficialName":null,"ParentVolcanoId":"ak286","ParentVolcano":"Togiak volcanics","AgeClass":"Pleistocene","AgeSource":"Hoare and Coonrad (1980) report a single K-Ar date of 0.76 Ma for the Togiak volcanics.","Composition":"basalt","IsMonitored":false,"VolcanoType":null,"NvewsThreat":null,"Description":null,"NameOrigin":"\"Togiak tuya\" is an informal name. The tuya is located near Togiak village and the Togiak River."},{"VolcanoId":"ak256","Vnum":null,"Volcano":"Snider Peak","OfficialName":"Snider Peak","ParentVolcanoId":"ak81","ParentVolcano":"Drum","AgeClass":"Pleistocene","AgeSource":"Richter and others (2006) show Drum as being from 0.6 to 0.2 Ma.","Composition":"rhyodacite","IsMonitored":false,"VolcanoType":"Rhyodacite dome with dacite flows","NvewsThreat":null,"Description":null,"NameOrigin":"\"Snider Peak\" was reported in 1903 as a local name, by T.G. Gerdine (Orth, 1971)."},{"VolcanoId":"ak237","Vnum":null,"Volcano":"Ruddy Mtn","OfficialName":"Ruddy Mountain","ParentVolcanoId":"ak81","ParentVolcano":"Drum","AgeClass":"Pleistocene","AgeSource":"Richter and others (2006) show Drum as being from 0.6 to 0.2 Ma.","Composition":"dacite","IsMonitored":false,"VolcanoType":"Dome","NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak330","Vnum":null,"Volcano":"Zanetti, Mt","OfficialName":"Mount Zanetti","ParentVolcanoId":"ak326","ParentVolcano":"Wrangell","AgeClass":"SuspPleist","AgeSource":"Shown as Q on Richter and others, 2006 (SIM 2877)","Composition":"basalt","IsMonitored":false,"VolcanoType":"Cinder-spatter cone","NvewsThreat":null,"Description":null,"NameOrigin":"\"Mount Zanetti\" is a local name, reported by Mendenhall in 1903 (Orth, 1971)."},{"VolcanoId":"ak202","Vnum":null,"Volcano":"North Crater","OfficialName":"North Crater","ParentVolcanoId":"ak326","ParentVolcano":"Wrangell","AgeClass":"SuspPleist","AgeSource":"Shown as Q on Richter and others, 2006 (SIM 2877)","Composition":"andesite","IsMonitored":false,"VolcanoType":"Crater","NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak75","Vnum":null,"Volcano":"Devil Mountain Lakes","OfficialName":"Devil Mountain Lakes","ParentVolcanoId":"ak95","ParentVolcano":"Espenberg","AgeClass":"Pleistocene","AgeSource":"Beget and others, 1996: Devil Mountain Maar is 17,500 years B.P.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Maar","NvewsThreat":null,"Description":null,"NameOrigin":"The U.S. Geological Survey reported the name of Devil Mountain Lakes in 1950, with their name derived from nearby Devil Mountain (Orth, 1971)."},{"VolcanoId":"ak119","Vnum":null,"Volcano":"Horseshoe Island","OfficialName":null,"ParentVolcanoId":"ak147","ParentVolcano":"Katmai","AgeClass":"Historical","AgeSource":"Historical eruption (1912).","Composition":"dacite","IsMonitored":false,"VolcanoType":null,"NvewsThreat":null,"Description":"From Hildreth and others, 2003: \"The Horseshoe Island dome on the floor of Katmai Caldera (unit khi) was emplaced after the caldera collapse but before the caldera interior was first seen in 1916 (Griggs, 1922; Hildreth, 1991). Its volume was less than 0.001 cubic km of dacite (66 percent SiO2; Fenner, 1930, 1950; Hildreth, 1983).\"","NameOrigin":null},{"VolcanoId":"ak85","Vnum":null,"Volcano":"East Crater","OfficialName":"East Crater","ParentVolcanoId":"ak326","ParentVolcano":"Wrangell","AgeClass":"SuspPleist","AgeSource":"Shown as Q on Richter and others, 2006 (SIM 2877)","Composition":"andesite","IsMonitored":false,"VolcanoType":"Crater","NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak293","Vnum":null,"Volcano":"Twin Mtn","OfficialName":null,"ParentVolcanoId":"ak204","ParentVolcano":"Nunivak Island","AgeClass":"Pleistocene","AgeSource":"Hoare and others (1968) say that Twin Mountain is in an area of Nunivak Island that was active from 0.9 to 0.3 Ma (K-Ar dating). Mukasa and others (2007) obtained 40Ar/30Ar dates for the eastern end of Nunivak Island of 0.7 Ma and 0.15 Ma.","Composition":"basalt","IsMonitored":false,"VolcanoType":null,"NvewsThreat":null,"Description":null,"NameOrigin":"The U.S. Coast and Geodetic Survey reported the name for this feature as \"Twin Mountain\" in 1912, because the breached volcanic crater gives the appearance of two mountains (Orth, 1971)."},{"VolcanoId":"ak23","Vnum":null,"Volcano":"Binalik Maar","OfficialName":"Binalik Crater","ParentVolcanoId":"ak204","ParentVolcano":"Nunivak Island","AgeClass":"Pleistocene","AgeSource":"Hoare and others (1968) say that Binalik Maar is in an area of Nunivak Island that was active from 0.9 to 0.3 Ma (K-Ar dating). Mukasa and others (2007) obtained 40Ar/30Ar dates for the eastern end of Nunivak Island of 0.7 Ma and 0.15 Ma.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Maar","NvewsThreat":null,"Description":null,"NameOrigin":"\"Binalik Crater\" is a Cupik name reported in 1937 to the U.S. Army Air Force (Orth, 1971)."},{"VolcanoId":"ak5","Vnum":null,"Volcano":"Ahkiwiksnuk Maar","OfficialName":"Ahkiwiksnuk Lake","ParentVolcanoId":"ak204","ParentVolcano":"Nunivak Island","AgeClass":"Pleistocene","AgeSource":"Hoare and others (1968) say that Ahkiwiksnuk Maar is in an area of Nunivak Island that was active from 0.9 to 0.3 Ma (K-Ar dating). Mukasa and others (2007) obtained 40Ar/30Ar dates for the eastern end of Nunivak Island of 0.7 Ma and 0.15 Ma.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Maar","NvewsThreat":null,"Description":null,"NameOrigin":"Orth, 1971, reports that \"Ahkiwiksuk Lake\" is a Cupik name for a small lake in a crater, reported in 1949 by the U.S. Coast and Geodetic Survey as Ahkiwixnux."},{"VolcanoId":"ak197","Vnum":null,"Volcano":"Nanwaksjiak Maar","OfficialName":"Nanwaksjiak Crater","ParentVolcanoId":"ak204","ParentVolcano":"Nunivak Island","AgeClass":"Pleistocene","AgeSource":"Hoare and others (1968) report K-Ar ages of 0.22 and 0.34 for Nanwaksjiak Crater.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Maar","NvewsThreat":null,"Description":null,"NameOrigin":"\"Nanwaksjiak Crater\" is a Cup'ik name, reported as meaning \"deep hole,\" reported by the U.S. Coast and Geodetic Survey in 1949 (Orth, 1971)."},{"VolcanoId":"ak2","Vnum":null,"Volcano":"385 Maar","OfficialName":null,"ParentVolcanoId":"ak204","ParentVolcano":"Nunivak Island","AgeClass":null,"AgeSource":null,"Composition":null,"IsMonitored":false,"VolcanoType":"Maar","NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak272","Vnum":null,"Volcano":"Sugarloaf Peak","OfficialName":"Sugarloaf Peak","ParentVolcanoId":"ak248","ParentVolcano":"Semisopochnoi","AgeClass":"SuspHist","AgeSource":"Historical eruptions from Cerberus, possible eruptions from Sugarloaf Peak.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Cone","NvewsThreat":null,"Description":null,"NameOrigin":"\"Sugarloaf Peak\" was named by the U.S. Navy North Pacific Exploring Expedition in 1855 (Orth, 1971)."},{"VolcanoId":"ak177","Vnum":null,"Volcano":"Lakeshore Cone","OfficialName":"Lakeshore Cone","ParentVolcanoId":"ak248","ParentVolcano":"Semisopochnoi","AgeClass":"SuspHolo","AgeSource":"Coats (1959) thought that Lakeshore Cone was Recent.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Cone","NvewsThreat":null,"Description":"From Coats, 1959: \"Small scoria mound, with a maximum altitude of 585 feet, on the western shore of Fenner Lake. From the northwest side of its base two flows have escaped. The younger one has crossed the older one and the irregularities of its front now make minor coves and peninsulas near the northern extremity of Fenner Lake. The cone was not examined at close range and nothing is known of the composition of its lava flows.\" Coats' map labels Lakeshore Cone as basalt, however.","NameOrigin":"The U.S. Geological Survey named Lakeshore Cone in 1950, after its proximity to Fenner Lake (Orth, 1971)."},{"VolcanoId":"ak44","Vnum":null,"Volcano":"Mount Young","OfficialName":"Mount Young","ParentVolcanoId":"ak248","ParentVolcano":"Semisopochnoi","AgeClass":"Historical","AgeSource":"Historical eruptions from Cerberus.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Three composite cones","NvewsThreat":null,"Description":"   From Miller and others (1998): \"Mount Cerberus comprises three young, relatively undissected composite cones, all of nearly equal height (800 m) and with basal diameters somewhat more than 3 km (Coats, 1959).  The cones all have summit craters and are built principally of andesitic lava flows and pyroclastic rocks.  The easternmost crater is the smallest and most irregular in shape of the three; its vent has apparently shifted position slightly during or between past eruptions.  Lava flows appear to have originated from flank eruptions below 500 m altitude.\r\n   \"About 1.6 km east of Mount Cerberus is a partially destroyed cone, 260 m above sea level.  In the northeast part of the caldera, a small scoria mount (Lakeshore Cone; unit Qbl) was the source of two small lava flows 4 km northeast of Mount Cerberus, and a small scoria and agglutinate mound occurs 1.9 km south of Mount Cerberus.\r\n   \"Lava flows (unit Qbc) on the north flanks of Mount Cerberus appear in general to be younger than those on the south flank.  The youngest flow, as distinguished by degree of ash and vegetation cover, extends 600 m from the north base of the west summit and is probably no more than a century old according to Coats (1959)..  Other individual flows, consisting of single or multiple pulses as defined by sets of lava levees, can be identified.  Many older flows, particularly those on the north flanks of Mount Cerberus, have been largely buried beneath loose detrital material washed from the upper reaches of the cone.\r\n   \"A widespread blanket of pre-Cerberus dacitic ash, and younger andesitic or basaltic ash derived from the eruptions of Cerberus and two neighboring cones - Sugarloaf Peak and Lakeshore - may also have been active in historical time (Coats, 1959).  The summit of Sugarloaf Peak, 855 m high, lies about 4.4 km southeast of Mount Cerberus on the south coast of Semisopochnoi Island.  Composed chiefly of pyroclastics with intercalcated lava flows up to 2 m thick (unit Qbs), it has a double parasitic cone on its south flank from which vapor is sporadically emitted.\r\n   \"The oldest rocks exposed on Semisopochnoi Island are deeply eroded remnants of a late Tertiary-early Pleistocene volcano that had an eruption center or centers somewhere within the central part of the present island.  These rocks, termed the Pochnoi Volcanics, crop out northeast and west of Cerberus (unit Qtpl) (Coats, 1959).  Remnants of composite cones, perhaps slightly younger than and parasitic to a main volcano, are exposed around the margins of the island (unit Qtp).  Four other cones, one of which may have contained a lava lake in its summit crater, and associated lava flows (unit Qlo) are distinguishable from the composite cone remnants by being less eroded (Coats, 1959). The aforementioned deposits are glacially eroded, although the youngest of the cones only slightly so.  After glaciation, large volumes of dacitic pumice and ash were erupted during formation of an elliptic caldera (8 km in greatest width) and formed pyroclastic-flow deposits on the flanks of the volcano.  Deposits of post-caldera, pre-Cerberus eruptions are limited to sparse pyroclastic deposits and thin flows (unit Qbt) which extend from within the caldera out through a breach in the southeast wall.  Flows from Cerberus and the smaller Lakeshore Cone have nearly covered the caldera floor; a small arcuate lake, 2.5 km long, lies along the inner northeast rim of the caldera.  Nearly all deposits of Mount Cerberus are contained within the southern and western portion of the caldera.  Flows have breached the southern caldera wall in two places and extend 2-5 km to the coast.\"","NameOrigin":"Mount Cerberus was named by the U.S. Navy Survey Expedition (1935) \"because the three connected summits comprising the volcano are analogous to the three-headed dog of Greek mythology, the guardian of the entrance to the underworld\" (Orth, 1971)."},{"VolcanoId":"ak224","Vnum":null,"Volcano":"Pyre Peak","OfficialName":"Pyre Peak","ParentVolcanoId":"ak246","ParentVolcano":"Seguam","AgeClass":"Historical","AgeSource":"Historical eruptions.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Stratovolcano","NvewsThreat":null,"Description":null,"NameOrigin":"The name \"Pyre Peak\" was published by the U.S. Coast and Geodetic Survey in the 1954 Coast Pilot (Orth, 1971)."},{"VolcanoId":"ak71","Vnum":null,"Volcano":"Crater Ridge","OfficialName":"Crater Ridge","ParentVolcanoId":"ak90","ParentVolcano":"Edgecumbe","AgeClass":"Holocene","AgeSource":"Riehle and others (1989 - I-1983) state dacite lava flows of Crater Ridge to Holocene; domes to Pleistocene.","Composition":"dacite","IsMonitored":false,"VolcanoType":"Dome","NvewsThreat":null,"Description":null,"NameOrigin":"Crater Ridge was named by the U.S. Forest Service in 1936, because it is the north rim of a volcanic crater (Orth, 1971)."},{"VolcanoId":"ak207","Vnum":null,"Volcano":"Otter Island","OfficialName":null,"ParentVolcanoId":"ak264","ParentVolcano":"St. Paul Island","AgeClass":"SuspPleist","AgeSource":"The age of volcanism for Otter Island is unknown.","Composition":"basalt","IsMonitored":false,"VolcanoType":null,"NvewsThreat":null,"Description":null,"NameOrigin":"\"Otter Island\" is a translation of the Russian name \"O[strov] Bobrovoy\" meaning \"Otter Island\" (Orth, 1971)."},{"VolcanoId":"ak315","Vnum":null,"Volcano":"Walrus Island","OfficialName":"Walrus Island","ParentVolcanoId":"ak264","ParentVolcano":"St. Paul Island","AgeClass":"SuspPleist","AgeSource":"The age of volcanism on Walrus Island is unknown.","Composition":"basalt","IsMonitored":false,"VolcanoType":null,"NvewsThreat":null,"Description":null,"NameOrigin":"\"Walrus Island\" is a translation from the Russian name, \"O[strov] Morzhovoy,\" meaning \"Walrus Island,\" published by Sarichev in 1826 (Orth, 1971)."},{"VolcanoId":"ak244","Vnum":null,"Volcano":"Sea Lion Rock","OfficialName":"Sea Lion Rock","ParentVolcanoId":"ak264","ParentVolcano":"St. Paul Island","AgeClass":"SuspPleist","AgeSource":"The age of volcanism on Sea Lion Rock is unknown.","Composition":"basalt","IsMonitored":false,"VolcanoType":null,"NvewsThreat":null,"Description":null,"NameOrigin":"This island had the Russian name \"sivuchiy,\" meaning \"sea-lion,\" translated and published by the U.S. Coast and Geodetic Survey in 1875. Elliott (1881) called it \"Seevitchie Kammin [sea-lion rock]\" (Orth, 1971)."},{"VolcanoId":"ak267","Vnum":null,"Volcano":"Stuart Hill","OfficialName":"Stuart Mountain","ParentVolcanoId":"ak262","ParentVolcano":"St. Michael","AgeClass":"SuspHolo","AgeSource":"Mukasa and others (2007) produced several 40Ar/39Ar age dates for the St. Michael volcanic field: from 0.80 +/-0.03 Ma, to (at Crater Mountain) 0.37+/-0.02 Ma). Aboriginal legends suggest that that most recent eruptions were 2000-3000 years ago.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Shield volcano","NvewsThreat":null,"Description":null,"NameOrigin":"The U.S. Coast and Geodetic Survey named Stuart Mountain in 1898 (Orth, 1971)."},{"VolcanoId":"ak69","Vnum":null,"Volcano":"Crater Mtn 1","OfficialName":null,"ParentVolcanoId":"ak262","ParentVolcano":"St. Michael","AgeClass":"SuspPleist","AgeSource":"Hoare and Condon (1971) map this as Pleistocene.\r\nMukasa and others (2007) produced several 40Ar/39Ar age dates for the St. Michael volcanic field: from 0.80 +/-0.03 Ma, to (at Crater Mountain) 0.37+/-0.02 Ma). Aboriginal legends suggest that that most re","Composition":"basalt","IsMonitored":false,"VolcanoType":"Cone","NvewsThreat":null,"Description":null,"NameOrigin":"Crater Mountain was named in 1898 by the U.S. Coast and Geodetic Survey (Orth, 1971)."},{"VolcanoId":"ak263","Vnum":null,"Volcano":"St. Michael Mtn 1","OfficialName":"Saint Michael Mountain","ParentVolcanoId":"ak262","ParentVolcano":"St. Michael","AgeClass":"SuspHolo","AgeSource":"Mukasa and others (2007) produced several 40Ar/39Ar age dates for the St. Michael volcanic field: from 0.80 +/-0.03 Ma, to (at Crater Mountain) 0.37+/-0.02 Ma). Aboriginal legends suggest that that most recent eruptions were 2000-3000 years ago.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Cone","NvewsThreat":null,"Description":null,"NameOrigin":"\"Saint Michael Mountain\" is a local name, reported by the U.S. Coast and Geodetic survey in 1898 (Orth, 1971)."},{"VolcanoId":"ak70","Vnum":null,"Volcano":"Crater Peak","OfficialName":"Crater Peak","ParentVolcanoId":"ak260","ParentVolcano":"Spurr","AgeClass":"Historical","AgeSource":"Historical eruptions (1953, 1992).","Composition":"andesite","IsMonitored":false,"VolcanoType":"Satellite cone","NvewsThreat":null,"Description":null,"NameOrigin":"Crater Peak was named by S.R. Capps and R.H Sargent, during discovery and mapping in 1927 (Orth, 1971)."},{"VolcanoId":"ak319","Vnum":null,"Volcano":"West Maar","OfficialName":null,"ParentVolcanoId":"ak296","ParentVolcano":"Ukinrek Maars","AgeClass":"Historical","AgeSource":"Historical eruption (1977).","Composition":"basalt","IsMonitored":false,"VolcanoType":"Maar","NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak86","Vnum":null,"Volcano":"East Maar","OfficialName":null,"ParentVolcanoId":"ak296","ParentVolcano":"Ukinrek Maars","AgeClass":"Historical","AgeSource":"Historical eruption (1977).","Composition":"basalt","IsMonitored":false,"VolcanoType":"Maar","NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak294","Vnum":null,"Volcano":"Ugashik caldera","OfficialName":null,"ParentVolcanoId":"ak295","ParentVolcano":"Ugashik-Peulik","AgeClass":"SuspHolo","AgeSource":"Miller (2004) reports a caldera age of 40,000 yr BP, based on 14C and K-Ar age dates. At least one post-caldera dome (Dome I)","Composition":"mixed","IsMonitored":false,"VolcanoType":"Pleistocene caldera","NvewsThreat":null,"Description":null,"NameOrigin":"\"Ugashik Caldera\" is an informal name, for Mount Ugashik which is part of the caldera. The name \"Mount Ugashik\" was reported in 1902 by J.L. McPherson, and published in 1921 by G.C. Martin (Orth, 1971)."},{"VolcanoId":"ak212","Vnum":null,"Volcano":"Peulik","OfficialName":"Mount Peulik","ParentVolcanoId":"ak295","ParentVolcano":"Ugashik-Peulik","AgeClass":"SuspHist","AgeSource":"Miller (2004) presumes a Holocene age for Peulik, given its lack of glaciated features and possible historical eruptions.","Composition":"andesite","IsMonitored":false,"VolcanoType":"Stratovolcano with summit and flank domes","NvewsThreat":null,"Description":null,"NameOrigin":"\"Mount Peulik\" was reported in 1902 by W.H. Osgood, U.S. Department of Agriculture, as an Aleut name, with an alternative name of \"Smoky Mountain.\" According to G.C. Martin, \"Peulik\" means \"smoking\" or \"smoking mountain\" (Orth, 1971)."},{"VolcanoId":"ak191","Vnum":null,"Volcano":"Metcalf Domes","OfficialName":null,"ParentVolcanoId":"ak29","ParentVolcano":"Bogoslof","AgeClass":"Historical","AgeSource":"Historical eruptions.","Composition":"unknown","IsMonitored":false,"VolcanoType":"Former dome","NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak190","Vnum":null,"Volcano":"McCulloch Peak","OfficialName":"McCulloch Rock","ParentVolcanoId":"ak29","ParentVolcano":"Bogoslof","AgeClass":"Historical","AgeSource":"Historical eruptions.","Composition":"unknown","IsMonitored":false,"VolcanoType":"Obliterated exploded dome","NvewsThreat":null,"Description":null,"NameOrigin":"\"McCulloch Rock\" was published as a name in the 1954 U.S. Coast and Geodetic Survey Coast Pilot (Orth, 1971)."},{"VolcanoId":"ak276","Vnum":null,"Volcano":"Tahoma Peak","OfficialName":null,"ParentVolcanoId":"ak29","ParentVolcano":"Bogoslof","AgeClass":"Historical","AgeSource":"Historical eruptions.","Composition":"andesite","IsMonitored":false,"VolcanoType":"Dome with crater, exploded and eroded","NvewsThreat":null,"Description":null,"NameOrigin":"\"Tahoma Peak\" was named for the cutter Tahoma."},{"VolcanoId":"ak251","Vnum":null,"Volcano":"Ship Rock","OfficialName":null,"ParentVolcanoId":"ak29","ParentVolcano":"Bogoslof","AgeClass":"Historical","AgeSource":"Historical eruptions.","Composition":"andesite","IsMonitored":false,"VolcanoType":"Former dome","NvewsThreat":null,"Description":null,"NameOrigin":"\"Ship Rock\" is a translation from Russian \"K[amen] Korabi,\" named by Tebenkov (1852). Lutke (1836) called it \"Tanghinakh,\" possibly from the Aleut word \"tangidak,\" which, according to R.H. Geoghegan, means \"islet or small island\" (Orth, 1971)."},{"VolcanoId":"ak282","Vnum":null,"Volcano":"The Sisters","OfficialName":null,"ParentVolcanoId":"ak262","ParentVolcano":"St. Michael","AgeClass":"Pleistocene","AgeSource":"Mukasa and others (2007) produced several 40Ar/39Ar age dates for the St. Michael volcanic field: from 0.80 +/-0.03 Ma, to (at Crater Mountain) 0.37+/-0.02 Ma). Aboriginal legends suggest that that most recent eruptions were 2000-3000 years ago.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Cone","NvewsThreat":null,"Description":null,"NameOrigin":"\"The Sisters\" were named in 1898 by the U.S. Coast and Geodetic Survey (Orth, 1971)."},{"VolcanoId":"ak230","Vnum":null,"Volcano":"Red Cinder Dome","OfficialName":"Red Cinder Dome","ParentVolcanoId":"ak188","ParentVolcano":"Makushin","AgeClass":"Pleistocene","AgeSource":"McConnell and others (1997) report this vent as Pleistocene, and state that a single age from a volcanic deposit west of Driftwood Valley (within the same Qom unit of Red Cinder Dome) yielded an 40Ar/39Ar isochron age of 2.49 +/- 0.08 Ma.","Composition":"mafic","IsMonitored":false,"VolcanoType":"Cinder cone remnant","NvewsThreat":null,"Description":null,"NameOrigin":"\"Red Cinder Dome\" was named in 1937 by the U.S. Coast and Geodetic Survey because it \"is a large reddish cinder dune [sic], a sort of half crater\" (Orth, 1971)."},{"VolcanoId":"ak179","Vnum":null,"Volcano":"Lava Peak","OfficialName":null,"ParentVolcanoId":"ak6","ParentVolcano":"Akutan","AgeClass":"Pleistocene","AgeSource":"Richter and others (1998) map this vent as part of the ancestral Akutan volcano. A 40Ar/39Ar age date of 1.41 Ma has been obtained from this unit.","Composition":"andesite","IsMonitored":false,"VolcanoType":"Vent","NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak209","Vnum":null,"Volcano":"Pakushin cone","OfficialName":null,"ParentVolcanoId":"ak188","ParentVolcano":"Makushin","AgeClass":"Pleistocene","AgeSource":"McConnell and others (1997) report that 40Ar/39Ar age determinations for Pakushin Cone place the time of eruption at approximately 22 +/- 5 ka.","Composition":"mafic","IsMonitored":false,"VolcanoType":"Composite cone","NvewsThreat":null,"Description":null,"NameOrigin":"\"Pakushin cone\" is an informal name."},{"VolcanoId":"ak271","Vnum":null,"Volcano":"Sugarloaf","OfficialName":"Sugarloaf Mountain","ParentVolcanoId":"ak188","ParentVolcano":"Makushin","AgeClass":"Pleistocene","AgeSource":"McConnell and others (1997) report that Sugarloaf is Holocene, and give 40Ar/39Ar age determinations of not older than 33,000 years.","Composition":"basaltic_andesite","IsMonitored":false,"VolcanoType":"Pyroclastic cone","NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak216","Vnum":null,"Volcano":"Point Kadin vents","OfficialName":"Point Kadin","ParentVolcanoId":"ak188","ParentVolcano":"Makushin","AgeClass":"SuspHolo","AgeSource":"McConnell and others (1997) these vents are more similar to younger Makushin lavas than older ones, and are of Holocene age.","Composition":"andesite","IsMonitored":false,"VolcanoType":"10 small cones and explosion craters","NvewsThreat":null,"Description":null,"NameOrigin":"\"Point Kadin vents\" is an informal name, after Point Kadin, where they are located. Point Kadin was was first named \"Makushin Cape\" in 1888. Later, the U.S. Coast and Geodetic Survey named it Point Kadin, and published that name in the 1938 Coast Pilot (Orth, 1971)."},{"VolcanoId":"ak97","Vnum":null,"Volcano":"Faris Peak","OfficialName":"Faris Peak","ParentVolcanoId":"ak322","ParentVolcano":"Westdahl","AgeClass":"Holocene","AgeSource":"Calvert and others (2005) state that Faris Peak is Holocene.","Composition":"mafic","IsMonitored":false,"VolcanoType":"Cone","NvewsThreat":null,"Description":null,"NameOrigin":"Faris Peak was named by O.H. Tittmann, U.S. Coast and Geodetic Survey, for Robert Lee Faris, Assistant Director of the U.S. Coast and Geodetic Survey. Robert Faris determined the geographic position of this peak in 1901, while exploring with Ferdinand Westdahl's expedition (Orth, 1971)."},{"VolcanoId":"ak215","Vnum":null,"Volcano":"Pogromni's Sister","OfficialName":null,"ParentVolcanoId":"ak322","ParentVolcano":"Westdahl","AgeClass":"SuspPleist","AgeSource":"Calvert and others (2005) label Pogromni's Sister as Late Pleistocene.","Composition":"mafic","IsMonitored":false,"VolcanoType":"Stratovolcano","NvewsThreat":null,"Description":null,"NameOrigin":"\"Pogromni's Sister\" is an informal name."},{"VolcanoId":"ak36","Vnum":null,"Volcano":"Caldera One","OfficialName":null,"ParentVolcanoId":"ak182","ParentVolcano":"Little Sitkin","AgeClass":"SuspPleist","AgeSource":"Snyder (1959) places this caldera formation in the Tertiary or Quaternary.","Composition":"andesite","IsMonitored":false,"VolcanoType":"Caldera","NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak37","Vnum":null,"Volcano":"Caldera Two","OfficialName":null,"ParentVolcanoId":"ak182","ParentVolcano":"Little Sitkin","AgeClass":"SuspPleist","AgeSource":"Snyder (1959) places this caldera formation within the Quaternary.","Composition":"andesite","IsMonitored":false,"VolcanoType":"Caldera","NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak185","Vnum":null,"Volcano":"Lost Jim Cone","OfficialName":"Lost Jim Cone","ParentVolcanoId":"ak125","ParentVolcano":"Imuruk Lake Volc Field","AgeClass":"Holocene","AgeSource":"Wood and Kienle (1990) report that The Lost Jim Flow, part of the Imuruk Lake volcanics, was erupted 1,655 yBP (radiocarbon dating).","Composition":"basalt","IsMonitored":false,"VolcanoType":"Cone","NvewsThreat":null,"Description":"   From Hopkins (1956): \"The Lost Jim lava flow is a pahoehoe flow of olivine basalt, the youngest of a series of basaltic lava flows of Quaternary age comprising a lava plateau surrounding Imuruk Lake, Seward Peninsula, Alaska.  The Lost Jim flow extends 17-1/2 miles westward from the source cone and covers more than 60 square miles.  It ranges in thickness from 10 to about 150 feet.\r\n   \"Surficial features and internal structures indicate that the flow was emitted largely during early and late intense phases of a single eruption.  The early part of the flow is rugged and has a surface that ranges in relief from 20 to 40 feet and that consists of pressure ridges, lava platforms, and lava plateaus intermingled with collapse sinks and broad, hummocky depressions.  The late part is smoother in detail but contains a series of exceptionally deep collapse sinks and deformation structures resembling miniature volcanoes along a great lava tube extending 12 miles westward from Lost Jim Cone.\r\n  \"The inferred history of the eruption begins with a period of quiet emission of lava during which the flow advanced by the flow-unit mechanism nearly to its present boundaries.  The early phase ended with the extrusion of cooler, more viscous lava represented now by patches of aa lava near Lost Jim Cone.\r\n  \"The late phase began when a surge of new lava intruded the base of the flow, arching the surface near the source vent.  Distributary lava tubes in use during the early phase were closed by displacements along concentric high-angle reverse faults surrounding the source vent, but an outlet to the surface was soon reopened above the vent; Lost Jim Cone was built during an ensuing ash eruption.  A larger outlet developed at the west base of the cone, and great quantities of new pahoehoe lava flooded the older part of the flow.  Part of the new surface lava came from beneath the domed area; the dome collapsed along the concentric fractures, forming a series of hogback ridges that now ring Lost Jim Cone.\"","NameOrigin":"D.M. Hopkins reported the name \"Lost Jim Cone\" in 1950; so named because while \"mapping the [lava] flow in 1947, a member of the Geological Survey field party was separated from the remainder of the group and lost for nearly a day\" (Orth, 1971)."},{"VolcanoId":"ak292","Vnum":null,"Volcano":"Twin Calderas","OfficialName":"Twin Calderas (SW)","ParentVolcanoId":"ak110","ParentVolcano":"Gosling Cone","AgeClass":"SuspPleist","AgeSource":"Hopkins (1963) considered the Twin Calderas to be Pleistocene. Wood and Kienle report that the Gosling volcanics (includes the Twin Calderas) have been dated to 0.9 and 0.8 Ma.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Shield Volcano","NvewsThreat":null,"Description":null,"NameOrigin":"D.M. Hopkins named the Twin Calderas in 1950, because \"at the summit of the cone there are two large cairns built by Inupiaq people before white men entered the country. The cairns are a conspicuous landmark from four miles away in any direction\" (Orth, 1971)."},{"VolcanoId":"ak110","Vnum":null,"Volcano":"Gosling Cone","OfficialName":"Gosling Cone","ParentVolcanoId":"ak110","ParentVolcano":"Gosling Cone","AgeClass":"SuspPleist","AgeSource":"Hopkins (1963) believed the Gosling Volcanics were Pleistocene. Wood and Kienle report that they have been dated to 0.9 and 0.8 Ma.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Stratovolcano","NvewsThreat":null,"Description":null,"NameOrigin":"Gosling Cone's name was reported in 1950 by D.M. Hopkins, U.S. Geological Survey, and named because his field party caught \"four half-grown goslings near the base of the cone in 1947\" (Orth, 1971)."},{"VolcanoId":"ak273","Vnum":null,"Volcano":"Summit cone","OfficialName":null,"ParentVolcanoId":"ak105","ParentVolcano":"Frosty","AgeClass":"SuspPleist","AgeSource":"Waldron (1961) has these units straddle the \"Pleistocene\" line.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Stratovolcano","NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak94","Vnum":null,"Volcano":"Emmons, Mt","OfficialName":"Mount Emmons","ParentVolcanoId":"ak93","ParentVolcano":"Emmons Lake Volcanic Center","AgeClass":"SuspHolo","AgeSource":"Waythomas and others (2006) believe that Mount Emmons has been active from ~20,000 years to near-historical times.","Composition":"andesite","IsMonitored":false,"VolcanoType":"Small intracaldera stratocone","NvewsThreat":null,"Description":null,"NameOrigin":"\"Mount Emmons\" is a local name, published on a 1943 U.S. Geological Survey map (Orth, 1971)."},{"VolcanoId":"ak92","Vnum":null,"Volcano":"Emmons Lake Caldera","OfficialName":null,"ParentVolcanoId":"ak93","ParentVolcano":"Emmons Lake Volcanic Center","AgeClass":"Pleistocene","AgeSource":"Waythomas and others (2006) state that last CFE was 26,000 years ago.","Composition":"felsic","IsMonitored":false,"VolcanoType":"Caldera","NvewsThreat":null,"Description":null,"NameOrigin":"\"Emmons Lake Caldera\" is an informal name applied to the caldera near Mount Emmons and Emmons Lake."},{"VolcanoId":"ak113","Vnum":null,"Volcano":"Hague, Mt","OfficialName":"Mount Hague","ParentVolcanoId":"ak93","ParentVolcano":"Emmons Lake Volcanic Center","AgeClass":"SuspHolo","AgeSource":"Waythomas and others (2006) believe Mount Hague has had Holocene lava flows, based on morphology and weathering.","Composition":"andesite","IsMonitored":false,"VolcanoType":"Stratocone","NvewsThreat":null,"Description":null,"NameOrigin":"Mount Hague was named by the U.S. Geological Survey in 1929 (Orth, 1971)."},{"VolcanoId":"ak50","Vnum":null,"Volcano":"Churchill, Mt","OfficialName":"Mount Churchill","ParentVolcanoId":"ak50","ParentVolcano":"Churchill, Mt","AgeClass":"Holocene","AgeSource":"Richter and others (1995) show that the Holocene (1,920 and 1,280 y BP) White River ash came from Mt. Churchill.","Composition":"unknown","IsMonitored":false,"VolcanoType":"Stratovolcano","NvewsThreat":"High Threat","Description":"   From Wood and Kienle (1990): \"The Wrangell volcanic field extends from the Copper River Basic east-southeast across southcentral Alaska into the Yukon Territory of Canada, a distance of more than 250 km.  At its west end the field includes the Quaternary volcanoes of Mount Wrangell, Mount Drum, Mount Sanford, Tanada, and Capital Mountain, which are described separately.  In Alaska the field includes many of the higher elevations of the Wrangell Mountains and contiguous parts of the eastern Alaska Range and the St. Elias Mountains; it is in large part snow- and ice-covered.\r\n   \"The eastern part of the field is characterized chiefly by extensive and thick sequences of relatively flat-lying andesite and basaltic andesite flows, probably mostly from a number of coalescing shield volcanoes.  Thick dacite flows and dacite and rhyolite domes, pyroclastic rocks, and subvolcanic plutons occur at and around some of the known eruptive centers.  Available radiometric dates indicate that, in general, volcanic activity proceeded from east to west across the field.\r\n   \"Exceptions to the general east to west progression of eruptive activity include numerous Quaternary basalt and basaltic andesite cinder cones throughout the western half of the field, and the Holocene White River Ash source vent near the Yukon border.  The cinder cones, of both Pleistocene and Holocene age, occur along the north side of the field between Mount Drum and the Nabesna Glacier River system, where they are superimposed on older volcanic rocks.  Many of the cones retain their original constructional form, and most are \u003c1 km in diameter and \u003c100 m in height.  Mount Churchill * * * contains an ice-filled summit caldera 3 km wide.\"  McGimsey and others (1992) show that Mount Churchill is the source of the White River Ash, produced during two of the largest explosive eruptions in North America during the last 2000 years.  From Wood and Kienle (1990): \"The White River Ash covers most of the southern Yukon of Canada and part of the eastern Alaska.  It is the product of two separate Plinian eeruptions, the combined tephra volume likely exceeding 30 cubic km.\"","NameOrigin":"Mount Churchill was named in 1965 by the Alaska State Legislature in Senate Joint Resolution 29, for Winston Churchill, 1874-1965, English statesman (Orth, 1971)."},{"VolcanoId":"ak32","Vnum":null,"Volcano":"Bona, Mt","OfficialName":"Mount Bona","ParentVolcanoId":"ak50","ParentVolcano":"Churchill, Mt","AgeClass":"SuspHolo","AgeSource":null,"Composition":"unknown","IsMonitored":false,"VolcanoType":"Stratovolcano","NvewsThreat":null,"Description":"   From Miller and Richter (1994): \"Both Mt. Bona and Mt. Churchill are high snow- and ice-covered mountains in the eastern part of the Wrangell volcanic field.  They appear to be relatively young constructional forms.  Mt. Bona, the highest peak (5,005) in the Wrangell Mountains, may be a small stratocone built upon a high platform of Pennsylvanian and Lower Permian rocks (MacKevett, 1978).\"  McGimsey and others (1992) state that Mount Churchill is now known to be the source of the White River Ash, produced during two of the largest explosive eruptions in North America during the past 2000 years.","NameOrigin":"Mount Bona was named by His Royal Highness, Prince Luigi Amedeo di Savoia, Duke of the Abruzzi, for the Bona, his racing yacht (Filippi, 1900; Orth, 1971)."},{"VolcanoId":"ak43","Vnum":null,"Volcano":"Castle Rock","OfficialName":null,"ParentVolcanoId":"ak29","ParentVolcano":"Bogoslof","AgeClass":"Historical","AgeSource":"Historical eruptions.","Composition":"andesite","IsMonitored":false,"VolcanoType":"Eroded dome remnant","NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak275","Vnum":null,"Volcano":"Table Top Mtn","OfficialName":"Table Top Mountain","ParentVolcanoId":"ak275","ParentVolcano":"Table Top Mtn","AgeClass":"SuspHolo","AgeSource":"Nye (personal commun., 2007) believes Table Top is Holocene. 40Ar/39Ar age dates as printed in McConnell and others (1997) show Table Top as 68 +/- 14 ka - Pleistocene.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Pyroclastic cone","NvewsThreat":"Low Threat","Description":"   From Miller and others (1998): \"Tabletop Mountain, the eroded remains of of a pyroclastic cone encircled by flows originating from small flank vents, is 20 km northeast\" of Makushin Volcano.  Table Top is considered to be Holocene in age, and to represent a magmatic system separate from that of Makushin (Nye, personal commun., 2007).  From McConnell and others (1997): \"An 40Ar/39Ar age of 68+/-14 ka places this unit as the oldest satellite vent.  Basaltic lavas and tephra from Table Top Mountain northeast of Makushin Volcano and a small, glaciated ramp of lava north and west of the cone.\"","NameOrigin":"\"Table Top Mountain\" was published in the 1944 Aleutian Coast Pilot (Orth, 1971)."},{"VolcanoId":"ak324","Vnum":null,"Volcano":"Wide Bay cone","OfficialName":null,"ParentVolcanoId":"ak188","ParentVolcano":"Makushin","AgeClass":"SuspHolo","AgeSource":"Nye (personal commun., 2007) believes Wide Bay Cone is Holocene. Six 40Ar/39Ar age dates have a mean of 19 +/- 15 ka (McConnell and others, 1997).","Composition":"basalt","IsMonitored":false,"VolcanoType":"Cone","NvewsThreat":"Low Threat","Description":"   From Miller and others (1998): \"Wide Bay cone, a small symmetric cone with an oval summit crater, occupies the northwest edge of Unalaska Bay.\"  Wide Bay cone is Holocene in age, and is considered to represent a magmatic system separate from that of Makushin Volcano (Nye, personal commun., 2007).  From McConnell and others (1997): \"Basaltic tephra and lava flows form the monogenetic Wide Bay Cone near Eider Point, the easternmost volcano of the Makushin volcanic field.  Both tephra and lava flows are dominated by up to 20 vol.% of large, single phenocrysts and glomerocrysts of clinopyroxene.  The clinopyroxene is zoned and may reach 4 mm in diameter.  Additional important phenocryst phases include plagioclase (15 to 19 vol.%), olivine (1 to 5 vol.%), and minor magnetite in a microlite-rich, sideromelane groundmass.  Lowermost flows at the base of the cone are glacially striated although the cone remains well shaped with the summit vent depression preserved.\"","NameOrigin":"\"Wide Bay cone\" is an informal name, after the nearby Wide Bay."},{"VolcanoId":"ak223","Vnum":null,"Volcano":"Pyramid Island","OfficialName":"Pyramid Island","ParentVolcanoId":"ak73","ParentVolcano":"Davidof","AgeClass":"SuspHolo","AgeSource":"Smith and others (1978) suggest Holocene for Davidof.","Composition":"unknown","IsMonitored":false,"VolcanoType":"Caldera remnant","NvewsThreat":null,"Description":null,"NameOrigin":"Personnel on the U.S.S. Oglala named Pyramid Island in 1935, after its shape (Orth, 1971)."},{"VolcanoId":"ak184","Vnum":null,"Volcano":"Lopy Island","OfficialName":null,"ParentVolcanoId":"ak73","ParentVolcano":"Davidof","AgeClass":"SuspHolo","AgeSource":"Smith and others (1978) suggest Holocene for Davidof.","Composition":"unknown","IsMonitored":false,"VolcanoType":"Caldera remnant","NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak67","Vnum":null,"Volcano":"Crater Bay","OfficialName":"Crater Bay","ParentVolcanoId":"ak73","ParentVolcano":"Davidof","AgeClass":"SuspHolo","AgeSource":"Smith and others (1978) suggest Holocene for Davidof.","Composition":"unknown","IsMonitored":false,"VolcanoType":"Caldera remnant","NvewsThreat":null,"Description":null,"NameOrigin":"Crater Bay was named by the U.S. Coast and Geodetic Survey in 1928 because it is encircled by ridges of volcanic rock (Orth, 1971)."},{"VolcanoId":"ak253","Vnum":null,"Volcano":"Shrub","OfficialName":null,"ParentVolcanoId":"ak163","ParentVolcano":"Klawasi Group","AgeClass":null,"AgeSource":null,"Composition":null,"IsMonitored":false,"VolcanoType":"Mud volcano","NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak300","Vnum":null,"Volcano":"Upper Klawasi","OfficialName":null,"ParentVolcanoId":"ak163","ParentVolcano":"Klawasi Group","AgeClass":"","AgeSource":null,"Composition":null,"IsMonitored":false,"VolcanoType":"Mud volcano","NvewsThreat":null,"Description":null,"NameOrigin":"\"Upper Klawasi\" is an informal name."},{"VolcanoId":"ak186","Vnum":null,"Volcano":"Lower Klawasi","OfficialName":null,"ParentVolcanoId":"ak163","ParentVolcano":"Klawasi Group","AgeClass":null,"AgeSource":null,"Composition":null,"IsMonitored":false,"VolcanoType":"Mud volcano","NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak56","Vnum":null,"Volcano":"Cone A","OfficialName":null,"ParentVolcanoId":"ak206","ParentVolcano":"Okmok","AgeClass":"Historical","AgeSource":"Historical eruptions.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Polygenetic basaltic composite cone","NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak290","Vnum":null,"Volcano":"Tulik","OfficialName":"Tulik Volcano","ParentVolcanoId":"ak206","ParentVolcano":"Okmok","AgeClass":"SuspPleist","AgeSource":"Byers (1959) considered Tulik to be Quaternary.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Stratocone","NvewsThreat":null,"Description":null,"NameOrigin":"\"Tulik Volcano\" was published as \"Toulikskoi\" by Lutke (1836), as a Aleut name. Captain Tebenkov (1852) published it as \"So[pka] Tulikskaya.\" The name may be from the Aleut word \"tuliq,\" which R.H. Geoghegan says means \"crack\" or \"fissure\" (Orth, 1971)."},{"VolcanoId":"ak4","Vnum":null,"Volcano":"Ahding Ingrid Mtn","OfficialName":"Ahding Ingrid Mountain","ParentVolcanoId":"ak204","ParentVolcano":"Nunivak Island","AgeClass":"SuspPleist","AgeSource":"Beikman (1974) shows Ahding Ingrid Mountain as Quaternary.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Cone","NvewsThreat":null,"Description":null,"NameOrigin":"Orth, 1971, reports that \"Ahding Ingrid Mountain\" is a Cup'ik name meaning \"Ahding [river] Ingria [mountain]\" reported in 1949 by the U.S. Coast and Geodetic Survey. The \"d\" ending appears to have originated from a typographical error."},{"VolcanoId":"ak13","Vnum":null,"Volcano":"Andromeda Cone","OfficialName":"Andromeda Cone","ParentVolcanoId":"ak125","ParentVolcano":"Imuruk Lake Volc Field","AgeClass":"SuspPleist","AgeSource":"Hopkins (1963) considered the Andromeda Cone to be Pleistocene.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Cone","NvewsThreat":null,"Description":null,"NameOrigin":"The name \"Andromeda Cone\" was applied to this volcano in 1950 by D.M. Hopkins, who named this cone (and three others) after wild flowers that were common on the cones' slopes (Orth, 1971)."},{"VolcanoId":"ak15","Vnum":null,"Volcano":"Anvil Peak","OfficialName":"Anvil Peak","ParentVolcanoId":"ak248","ParentVolcano":"Semisopochnoi","AgeClass":"SuspPleist","AgeSource":"Coats (1959) thought this volcano was Late Pleistocene.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Cone","NvewsThreat":null,"Description":null,"NameOrigin":"The name \"Anvil Peak\" was first published in 1951 on a U.S.GS map, named after the flat area north of the summit (Orth, 1971)."},{"VolcanoId":"ak19","Vnum":null,"Volcano":"Atuk Mtn","OfficialName":"Atuk Mountain","ParentVolcanoId":"ak169","ParentVolcano":"Kookooligit Mountains","AgeClass":"Pleistocene","AgeSource":"Patton and Csejtey (1980) published 5 K-Ar age dates for Kookooligit lava flows, ranging from 1.46 Ma to 0.24 Ma. Mukasa and others (2007) have a single 40Ar/39Ar age date of 1.22 +/-0.02 Ma.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Cone","NvewsThreat":null,"Description":null,"NameOrigin":"\"Atuk Mountain\" is a Yup'ik name sometimes written \"Atak\" or \"Atik,\" meaning \"name,\" recommended to the U.S. Geological Survey in 1947 by the Savoonga village council (Orth, 1971)."},{"VolcanoId":"ak26","Vnum":null,"Volcano":"Blocky cone","OfficialName":null,"ParentVolcanoId":"ak14","ParentVolcano":"Aniakchak","AgeClass":"Holocene","AgeSource":"Neal and others (2001) believe Blocky Cone had strombolian eruptions within the last few hundred years.","Composition":"dacite","IsMonitored":false,"VolcanoType":"Scoria cone","NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak31","Vnum":null,"Volcano":"Bolshoi Dome","OfficialName":null,"ParentVolcanoId":"ak14","ParentVolcano":"Aniakchak","AgeClass":null,"AgeSource":null,"Composition":"dacite","IsMonitored":false,"VolcanoType":"Lava dome","NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak38","Vnum":null,"Volcano":"Camille Cone","OfficialName":"Camille Cone","ParentVolcanoId":"ak38","ParentVolcano":"Camille Cone","AgeClass":"SuspPleist","AgeSource":"Hopkins (1963) considered Camille Cone as Pleistocene.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Cone","NvewsThreat":null,"Description":null,"NameOrigin":"\"Camille Cone\" was reported as a place name in 1951 by Hopkins (Orth, 1971)."},{"VolcanoId":"ak42","Vnum":null,"Volcano":"Cassiope Cone","OfficialName":"Cassiope Cone","ParentVolcanoId":"ak125","ParentVolcano":"Imuruk Lake Volc Field","AgeClass":"SuspPleist","AgeSource":"Hopkins (1963) considered the Cassiope Cone to be Pleistocene.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Cone","NvewsThreat":null,"Description":null,"NameOrigin":"The name \"Cassiope Cone\" was reported by Hopkins in 1950. The cone was named for wildflowers which were common on the slopes of this cone and others in the area (Orth, 1971)."},{"VolcanoId":"ak53","Vnum":null,"Volcano":"Coats Caldera","OfficialName":null,"ParentVolcanoId":"ak329","ParentVolcano":"Yunaska","AgeClass":"SuspHolo","AgeSource":"Miller and others (1998) suspect the younger caldera on Yunaska is Holocene, based on non-glaciated associated pyroclastic deposits.","Composition":"unknown","IsMonitored":false,"VolcanoType":"Caldera","NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak91","Vnum":null,"Volcano":"Eickelberg Peak (Cone 8)","OfficialName":"Eickelberg Peak","ParentVolcanoId":"ak100","ParentVolcano":"Fisher","AgeClass":"Pleistocene","AgeSource":"Stelling and others (2005) report that argon data from material from cones #7 and #8 yielded an age of 55 +/- 44 ka.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Stratovolcano","NvewsThreat":null,"Description":"Eickelberg Peak, also classified as Cone #8 in Stelling and others, 2005, is a late Pleistocene stratocone. Stelling and others (2005) also report that argon data from material from cones #7 and #8 yielded an age of 55 +/- 44 ka.","NameOrigin":"\"Eickelberg Peak\" was a local name, published on a 1951 U.S. Geological Survey map (Orth, 1971)."},{"VolcanoId":"ak98","Vnum":null,"Volcano":"Finch, Mt","OfficialName":null,"ParentVolcanoId":"ak100","ParentVolcano":"Fisher","AgeClass":"SuspHist","AgeSource":"Historical eruption. Suspected site of 1826 eruption.","Composition":"andesite","IsMonitored":false,"VolcanoType":"Cone","NvewsThreat":null,"Description":"From Stelling and others, 2005: \"Mt. Finch is a 1-cubic-km edifice in the geographic center of the caldera composed of numerous interbedded pl+ol+cpx andesite lava and scoria layers. Fumarolic activity has hydrothermally altered the western flank of Mt. Finch. Its flat summit has a raised ridge around its outside edge, and a symmetrical ~70-m-deep central depression with several large down dropped blocks. These features suggest a partial summit collapse, although eruptive deposits from such an event are not recognized. Samples from Mt. Finch are compositionally less diverse (54-60 wt.% SiO2) than those of Turquoise Cone. Mt. Finch appears less eroded than Turquoise Cone, and the pumice fall layers from Turquoise Cone are found only near the base of Mt. Finch, suggesting that Mt. Finch is younger. Erosional and effusive eruptive deposits from the two vents appear to intermingle, suggesting that activity overlapped. Several small monogenetic eruptive centers are located forund the flanks of Mt. Finch, and deposits from an ~4-square-km field of small cones have covered much of the region between Turquoise Cone and Mt. Finch.\"","NameOrigin":"\"Mount Finch\" is an informal name applied to a volcanic peak within Fisher Caldera."},{"VolcanoId":"ak104","Vnum":null,"Volcano":"Fox Hill cone","OfficialName":"Fox Hill","ParentVolcanoId":"ak264","ParentVolcano":"St. Paul Island","AgeClass":"Holocene","AgeSource":"Winer and others (2004) present a radiocarbon age for a lava flow from Fox Hill as being 3230 +/- 40 14C yBP.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Cone","NvewsThreat":null,"Description":"From Winer, 2001: \"Basanite lava flows from four aligned vents coalesce to form the Fox Hill flow. The pahoehoe flow is studded with chunks of the breached cinder cone. Flow levees and channels are well presevered and the flow surface has little cover from eolian deposits. On the basis of a single high-precision AMS radiocarbon age-date, on carbon-bearing sediment buried by the lava flow (SP98-63), the age of the unit is 3230+/-40 ybp. Rock is crystal-poor olivine basalt.\"","NameOrigin":"\"Fox Hill\" is a local name, published by the U.S. Coast and Geodetic Survey in 1875 (Orth, 1971)."},{"VolcanoId":"ak107","Vnum":null,"Volcano":"Gas Rocks, the","OfficialName":"The Gas Rocks","ParentVolcanoId":"ak107","ParentVolcano":"Gas Rocks, the","AgeClass":"Pleistocene","AgeSource":"Hildreth and others (2007) obtained  two 40Ar/39Ar ages on groundmass concentrates from samples of The Gas Rocks dacite.  Sample U-1, from the small North Point Dome, yielded a weighted-mean plateau age of 25.7 +/- 1.4 ka, and sample U-2, from Dome 600, 2","Composition":"dacite","IsMonitored":false,"VolcanoType":"Dome cluster","NvewsThreat":null,"Description":"   From Hildreth and others (2007): \"The Gas Rocks cluster consists of three dacite domes and one stratified fragmental mafic cone.  A second mafic cone (Cone 245) is exposed in a lakeshore bluff 4 km due west of The Gas Rocks.  Viewed from a distance, the three high knobs that make up The Gas Rocks include two of the domes and mafic Cone 431 (the southeasternmost knob).\r\n   \"The third dacite dome is much lower, standing only ~45 m above the lake on the north point of The Gas Rocks peninsula.  Separated by a linear trough from the much higher adjacent dome, North Point Dome appears to be an independent extrusion rather than a thick coulee issuing from its neighbor, an inference supported by its slightly more evolved composition.  The larger domes, Domes 600 and 700, have 180 and 210 m relief, respectively, above the lake.  Dome 600 appears to be a single simple extrusion, as shown by the steep jointing that flares slightly outward toward the top of its northeast face. Nonetheless, a pair of lava flows, each 10 to 15 m thick, extends to the shoreline from the foot of that face.  In common with a lava flow associated with North Point Dome, these flows have been truncated and thinned by the ice that flowed northwestward down the lake basin.  Dome 700 likewise has steep jointing on its sheer east face, but the moderately dipping sheeting on its west slope suggests serial extrusion of a few exogenous lobes.  Little or no glassy or pumiceous carapace remains on any of the domes, which were all completely submerged and scoured by glacial ice.  The deep interior exposure on the steep northeast faces of the two highest domes owes to enhanced erosion by the principal glacial lobe that flowed northwestward toward Bristol Bay.\r\n   \"All three domes consist of phenocryst-rich dacite. * * * We determined two 40Ar/39Ar ages on groundmass concentrates from samples of The Gas Rocks dacite.  Sample U-1, from the small North Point Dome, yielded a weighted-mean plateau age of 25.7 +/- 1.4 ka, and sample U-2, from Dome 600, 23.3 +/- 1.2 ka.  At their extremes, the two error envelopes just overlap, although nothing on the ground is known to contradict a younger age for the larger dome.  Because of their petrographic and compositional similarity, it cannot be excluded that the three domes are essentially contemporaneous, plausibly fed by a common dike, the northwesterly strike of which would be similar to the present-day plate-convergence direction (which might in turn influence the direction of maximum horizontal compression).\"","NameOrigin":"\"The Gas Rocks\" is a local name, reported by W.R. Smith and A.A. Baker (in Brooks and others, 1924) (Orth, 1971)."},{"VolcanoId":"ak114","Vnum":null,"Volcano":"Half Cone","OfficialName":"Half Cone","ParentVolcanoId":"ak14","ParentVolcano":"Aniakchak","AgeClass":"Holocene","AgeSource":"Neal and others (2001) believe Half Cone had explosive eruptions about 560 y BP.","Composition":"dacite","IsMonitored":false,"VolcanoType":"Intracaldera stratovolcano","NvewsThreat":null,"Description":null,"NameOrigin":"\"Half Cone\" is a descriptive name given in 1923 by R.H. Sargent, U.S.GS (Orth, 1971)."},{"VolcanoId":"ak122","Vnum":null,"Volcano":"Idak, Mt","OfficialName":"Mount Idak","ParentVolcanoId":"ak206","ParentVolcano":"Okmok","AgeClass":"SuspPleist","AgeSource":"Byers (1959) considered Mount Idak to be Quaternary.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Cone","NvewsThreat":null,"Description":null,"NameOrigin":"Mount Idak's name was originally published as Idak Peak by the U.S. Army Corps of Engineers in 1942, and later published as Mount Idak by the U.S. Geological Survey (Orth, 1971)."},{"VolcanoId":"ak126","Vnum":null,"Volcano":"Indooli Mtn","OfficialName":"Indooli Mountain","ParentVolcanoId":"ak204","ParentVolcano":"Nunivak Island","AgeClass":"SuspPleist","AgeSource":"Beikman (1974) shows Indooli Mountain as Quaternary.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Cone","NvewsThreat":null,"Description":null,"NameOrigin":"\"Indooli Mountain\" is a Cup'ik name obtained in 1949 by U.S. Coast and Geodetic Survey (Orth, 1971)."},{"VolcanoId":"ak129","Vnum":null,"Volcano":"Ingri Butte","OfficialName":"Ingri Butte","ParentVolcanoId":"ak204","ParentVolcano":"Nunivak Island","AgeClass":null,"AgeSource":"Tertiary!","Composition":"basalt","IsMonitored":false,"VolcanoType":"Cone","NvewsThreat":null,"Description":null,"NameOrigin":"\"Ingri Butte\" is reported as a Cup'ik name meaning \"mountain\" reported in 1949 by U.S. Coast and Geodetic Survey (Orth, 1971)."},{"VolcanoId":"ak130","Vnum":null,"Volcano":"Ingrijoak Hills","OfficialName":"Ingrijoak Hills","ParentVolcanoId":"ak204","ParentVolcano":"Nunivak Island","AgeClass":"Pleistocene","AgeSource":"Hoare and others (1968) show Ingrijoak Hills as 1.7 to 1.5 Ma.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Cone","NvewsThreat":null,"Description":null,"NameOrigin":"\"Ingrijoak Hills\" is reported as a Cup'ik name referring to two hills reported in 1949 by U.S. Coast and Geodetic Survey (Orth, 1971)."},{"VolcanoId":"ak131","Vnum":null,"Volcano":"Ingrilukat-Naskorat Hill","OfficialName":"Ingrilukat-Naskorat Hill","ParentVolcanoId":"ak204","ParentVolcano":"Nunivak Island","AgeClass":"Pleistocene","AgeSource":"Hoare and others (1968) show Ingrilukat-Naskorat Hill as 1.7 to 1.5 Ma.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Cone","NvewsThreat":null,"Description":null,"NameOrigin":"Ingrilukat-Naskorat Hill is reported as a Cup'ik name meaning \"head of the small hills\" reported in 1949 by U.S. Coast and Geodetic Survey (Orth, 1971). U.S. Board of Geographic Names url: https://edits.nationalmap.gov/apps/gaz-domestic/public/gaz-record/1403854"},{"VolcanoId":"ak132","Vnum":null,"Volcano":"Ingriruk Hill","OfficialName":"Ingriruk Hill","ParentVolcanoId":"ak204","ParentVolcano":"Nunivak Island","AgeClass":null,"AgeSource":"Tertiary!","Composition":"basalt","IsMonitored":false,"VolcanoType":"Cone","NvewsThreat":null,"Description":null,"NameOrigin":"\"Ingriruk Hill\" was reported as a Yup'ik name in 1937 by the U.S. Army Air Force. (Orth, 1971)."},{"VolcanoId":"ak139","Vnum":null,"Volcano":"Jiskooksnuk Hill","OfficialName":"Jiskooksnuk Hill","ParentVolcanoId":"ak204","ParentVolcano":"Nunivak Island","AgeClass":"SuspPleist","AgeSource":"Beikman (1974) shows Jiskooksnuk Hill as Quaternary.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Cone","NvewsThreat":null,"Description":null,"NameOrigin":"\"Jiskooksnuk Hill\" is a Cup'ik name obtained in 1949 by the U.S. Coast and Geodetic Survey (Orth, 1971)."},{"VolcanoId":"ak137","Vnum":null,"Volcano":"Jag Peak","OfficialName":"Jag Peak","ParentVolcanoId":"ak206","ParentVolcano":"Okmok","AgeClass":"SuspPleist","AgeSource":"Byers (1959) considered Jag Peak to be Quaternary.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Cone","NvewsThreat":null,"Description":null,"NameOrigin":"The name \"Jag Peak\" was published by Byers in 1959 (Orth, 1971)."},{"VolcanoId":"ak140","Vnum":null,"Volcano":"Johnson Glacier","OfficialName":null,"ParentVolcanoId":"ak124","ParentVolcano":"Iliamna","AgeClass":"Holocene","AgeSource":"may have had dome-building eruptions 1500 radiocarbon years ago (Waythomas and others, 2000).","Composition":"andesite","IsMonitored":false,"VolcanoType":"Former Dome","NvewsThreat":null,"Description":null,"NameOrigin":"\"Johnson Glacier\" is an informal name for these domes and tephras, named after the nearby Johnson Glacier."},{"VolcanoId":"ak153","Vnum":null,"Volcano":"Kikdooli Butte","OfficialName":"Kikdooli Butte","ParentVolcanoId":"ak204","ParentVolcano":"Nunivak Island","AgeClass":"SuspPleist","AgeSource":"Beikman (1974) shows Kikdooli Butte as Quaternary.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Cone","NvewsThreat":null,"Description":null,"NameOrigin":"\"Kikdooli Butte\" is a Cup'ik name obtained by the U.S. Coast and Geodetic Survey in 1949 (Orth, 1971)."},{"VolcanoId":"ak154","Vnum":null,"Volcano":"Kikikyak Hill","OfficialName":"Kikikyak Hill","ParentVolcanoId":"ak204","ParentVolcano":"Nunivak Island","AgeClass":"Pleistocene","AgeSource":"Hoare and others (1968) show Kikikyak Hill as Quaternary.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Cone","NvewsThreat":null,"Description":null,"NameOrigin":"\"Kikikyak Hill\" is a Cup'ik name meaning \"island-like,\" reported by the U.S. Coast and Geodetic Survey in 1949 (Orth, 1971)."},{"VolcanoId":"ak156","Vnum":null,"Volcano":"Kimijooksuk Butte","OfficialName":"Kimijooksuk Butte","ParentVolcanoId":"ak204","ParentVolcano":"Nunivak Island","AgeClass":"Pleistocene","AgeSource":"Hoare and others (1968) show Kimijooksuk Butte as Quaternary","Composition":"basalt","IsMonitored":false,"VolcanoType":"Cone","NvewsThreat":null,"Description":null,"NameOrigin":"\"Kimijooksuk Butte\" is a Cup'ik name meaning \"two hills with the same base,\" according to the U.S. Coast and Geodetic Survey, 1949 (Orth, 1971)."},{"VolcanoId":"ak157","Vnum":null,"Volcano":"Kimiksthek Hill","OfficialName":"Kimiksthek Hill","ParentVolcanoId":"ak204","ParentVolcano":"Nunivak Island","AgeClass":"SuspPleist","AgeSource":"Hoare and others (1968) show Kimiksthek Hill as possibly Quaternary; Beikman (1974) labels it Tertiary.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Cone","NvewsThreat":null,"Description":null,"NameOrigin":"\"Kimiksthek Hill\" is a Cup'ik name obtained by the U.S. Coast and Geodetic Survey in 1949 (Orth, 1971)."},{"VolcanoId":"ak160","Vnum":null,"Volcano":"Kiolik Hill","OfficialName":"Kiolik Hill","ParentVolcanoId":"ak204","ParentVolcano":"Nunivak Island","AgeClass":"Pleistocene","AgeSource":"Hoare and others (1968) show Kiolik Hill as 1.7 to 1.5 Ma.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Cone","NvewsThreat":null,"Description":null,"NameOrigin":"\"Kiolik Hill\" is a Cup'ik name meaning \"rocky top,\" according to the U.S. Coast and Geodetic Survey, 1949 (Orth, 1971)."},{"VolcanoId":"ak155","Vnum":null,"Volcano":"South Killeak","OfficialName":"Killeak Lakes","ParentVolcanoId":"ak95","ParentVolcano":"Espenberg","AgeClass":"Pleistocene","AgeSource":"Beget and others, 1996: Killeak maar is \u003e40,000 years old, North Killeak maar somewhat older.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Maar","NvewsThreat":null,"Description":null,"NameOrigin":"\"Killeak Lakes\" is an Inupiaq name reported in 1950 by the U.S. Geological Survey, 1949 (Orth, 1971)."},{"VolcanoId":"ak162","Vnum":null,"Volcano":"Kittiwake Pond","OfficialName":"Kittiwake Pond","ParentVolcanoId":"ak34","ParentVolcano":"Buldir","AgeClass":"SuspHolo","AgeSource":"unknown - no real data. Smith and Shaw (1975) suggest Buldir is Holocene, however.","Composition":"unknown","IsMonitored":false,"VolcanoType":"Maar","NvewsThreat":null,"Description":null,"NameOrigin":"Kittiwake Pond was named by Coats (1953), presumably for the Pacific kittiwake (Rissa tridachyla pollicaris), a gull-like bird (Orth, 1971)."},{"VolcanoId":"ak176","Vnum":null,"Volcano":"Lake Hill","OfficialName":"Lake Hill","ParentVolcanoId":"ak264","ParentVolcano":"St. Paul Island","AgeClass":"Pleistocene","AgeSource":"Winer (2001) shows radiocarbon evidence for Lake Hill being older than 17,800 +/- 800 years.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Cone","NvewsThreat":null,"Description":"From Winer, 2001: \"Lake Hill cinder cone complex and associated lava flow - Complex, multiple-vent, nested cinder cones at Lake Hill contain two crater lakes and have an associated lava flow. Glassy black agglutinated basalt in a welded horizone on a crater wall contains large (~5 mm) olivine phenocrysts\"","NameOrigin":"\"Lake Hill\" is a local name published in 1875 by the U.S. Coast and Geodetic Survey; so called because a small lake is located at its foot (Orth, 1971)."},{"VolcanoId":"ak194","Vnum":null,"Volcano":"Morzhovoi","OfficialName":null,"ParentVolcanoId":"ak194","ParentVolcano":"Morzhovoi","AgeClass":"SuspPleist","AgeSource":"Brophy, in Wood and Kienle (1990), states that the Morzhovoi volcanics are late Pliocene to early Pleistocene.","Composition":"mafic","IsMonitored":false,"VolcanoType":"Stratovolcano","NvewsThreat":null,"Description":"   From Wood and Kienle (1990): The \"Morzhovoi Volcanics constitute a late Pliocene to early Pleistocene basaltic and andesitic stratovolcano.  Volcanism culminated in the formation of a large collapsed crater.  Though presently ice-free, extensive Pleistocene glaciation has eroded most original stratovolcano features, including the actual crater rim, leaving long U-shaped valleys.\"  From Myers (1994): \"The oldest volcano [of the Cold Bay Volcanic Complex] Morzhovoi Volcano, is of late Tertiary to Quaternary age, lies on the southern edge of the Alaska Peninsula, and consists of basalts, andesites, and associated pyroclastic rocks (the Morzhovoi Volcanic Series). Because it has undergone extensive erosion, only remnants of the volcano remain. Isolated peaks, e.g. North and South Walrus Peaks, that are fragments of the original caldera rim range in height from 797 to 893 m.\"","NameOrigin":"\"Morzhovoi volcanics\" is an informal name, named after the nearby Morzhovoi Bay. Captain Tebenkov named the bay \"Za[liv] Morzhovoi\" in 1852, meaning \"Walrus Bay\" (Orth, 1971)."},{"VolcanoId":"ak200","Vnum":null,"Volcano":"New cone","OfficialName":null,"ParentVolcanoId":"ak14","ParentVolcano":"Aniakchak","AgeClass":null,"AgeSource":null,"Composition":"dacite","IsMonitored":false,"VolcanoType":"Explosive vent","NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak201","Vnum":null,"Volcano":"Nick's cone","OfficialName":null,"ParentVolcanoId":"ak100","ParentVolcano":"Fisher","AgeClass":null,"AgeSource":null,"Composition":null,"IsMonitored":false,"VolcanoType":"Cone","NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak213","Vnum":null,"Volcano":"Pochnoi","OfficialName":"Pochnoi Point","ParentVolcanoId":"ak248","ParentVolcano":"Semisopochnoi","AgeClass":"SuspPleist","AgeSource":"Coats (1959) states that these volcanics are older than the last glaciation, possibly even as old as the late Tertiary.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Shield volcano","NvewsThreat":null,"Description":null,"NameOrigin":"\"Pochoni\" is an informal name, after Pochnoi Point."},{"VolcanoId":"ak217","Vnum":null,"Volcano":"Polovina Hill N","OfficialName":"Polovina Hill","ParentVolcanoId":"ak264","ParentVolcano":"St. Paul Island","AgeClass":"SuspPleist","AgeSource":"Winer (2001) considers Polovina Hill as Quaternary. Polovina Hill is younger than the oldest lavas on St. Paul, however (540,000 years).","Composition":"basalt","IsMonitored":false,"VolcanoType":"Cone","NvewsThreat":null,"Description":"From Winer, 2001: \"Polovina Hill cinder cone complex and lava flow - Polovina Hill, a nested cinder cone complex with at least two constructional episodes, is composed of crudely stratified, unconsolidated, red and black scoria with block- and bomb-rich layers. Blocks and bombs include dense black tachylite blocks and spindle and breadcrust bombs; some are \u003e1 m in length. Polovina Hill has two craters; both are breached on the southwest side. On the younger crater rim are rare buff-colored, finely-vesiculated trachyte clasts with 62 wt% silica (SP98-35). Polovina Hill basanite lava flows form an extensive shield surrounding its large cone.\"","NameOrigin":"\"Polovina Hill\" is a Russian name meaning \"halfway\" (Orth, 1971)."},{"VolcanoId":"ak219","Vnum":null,"Volcano":"Pot Hill (North Hill)","OfficialName":"Pot Hill","ParentVolcanoId":"ak264","ParentVolcano":"St. Paul Island","AgeClass":"SuspPleist","AgeSource":"Winer (2001) considers North Hill as Quaternary. North Hill is younger than the oldest lavas on St. Paul, however (540,000 years).","Composition":"basalt","IsMonitored":false,"VolcanoType":"Cinder cone","NvewsThreat":null,"Description":"From Winer, 2001: \"North Hill is a complex cinder cone on the north coast. A lava flow issues from a breach on the southwest side of North Hill where a section of the cone and crater rim has been moved outward and rotated in a coherent mass. North Hill is surrounded by flows of dark grey, glassy, clinopyroxene- and olivine-phyric basanite.\"","NameOrigin":"\"North Hill\" was named in 1945 by a U.S. Geological Survey field party (Orth, 1971). This feature is called \"Pot Hill\" on some topographic maps."},{"VolcanoId":"ak222","Vnum":null,"Volcano":"Pumice Dome","OfficialName":null,"ParentVolcanoId":"ak14","ParentVolcano":"Aniakchak","AgeClass":null,"AgeSource":null,"Composition":"dacite","IsMonitored":false,"VolcanoType":"Lava dome","NvewsThreat":null,"Description":null,"NameOrigin":"\"Pumice Dome\" is an informal name."},{"VolcanoId":"ak225","Vnum":null,"Volcano":"Pyro Hill","OfficialName":null,"ParentVolcanoId":"ak100","ParentVolcano":"Fisher","AgeClass":null,"AgeSource":null,"Composition":null,"IsMonitored":false,"VolcanoType":"Maar","NvewsThreat":null,"Description":null,"NameOrigin":"\"Pyro Hill\" is an informal name."},{"VolcanoId":"ak227","Vnum":null,"Volcano":"Ragged Top","OfficialName":"Ragged Top","ParentVolcanoId":"ak248","ParentVolcano":"Semisopochnoi","AgeClass":"SuspPleist","AgeSource":"Coats (1959) states that these volcanics are older than the last glaciation, possibly even as old as the late Tertiary.","Composition":"mafic","IsMonitored":false,"VolcanoType":"Stratovolcano","NvewsThreat":null,"Description":null,"NameOrigin":"\"Ragged Top\" was named by the U.S. Geological Survey in 1932, \"because of the very rugged topography on the mountain top\" (Orth, 1971)."},{"VolcanoId":"ak232","Vnum":null,"Volcano":"Rhododendron Cone","OfficialName":"Rhododendron Cone","ParentVolcanoId":"ak110","ParentVolcano":"Gosling Cone","AgeClass":"SuspPleist","AgeSource":"Hopkins (1963) considered the Rhododendron Cone to be Pleistocene.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Stratovolcano","NvewsThreat":null,"Description":null,"NameOrigin":"\"Rhododendron Cone\" was named in 1950 by D.M. Hopkins, who called it one of \"four conspicuous volcanic cones * * * named for wildflowers which are common on the slopes of all four cones\" (Orth, 1971)."},{"VolcanoId":"ak234","Vnum":null,"Volcano":"Roberts Mtn","OfficialName":"Mount Roberts","ParentVolcanoId":"ak204","ParentVolcano":"Nunivak Island","AgeClass":"Pleistocene","AgeSource":"Hoare and others (1968) date Mount Roberts between 0.9 and 0.3 Ma.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Stratovolcano","NvewsThreat":null,"Description":null,"NameOrigin":"\"Mount Roberts\" was reported as name for this feature around 1908, by the U.S. Coast and Geodetic Survey. Ivan Petroff applied the name \"Mt. Robe[r]t Lincoln\" to this feature in 1880. Baker (1906), notes that it was apparently so named in 1778 by E.W. Nelson, after then Honorable Robert Lincoln, Secretary of War, 1881-85, and eldest son of President Abraham Lincoln (Orth, 1971)."},{"VolcanoId":"ak238","Vnum":null,"Volcano":"Rush Hill NE crater","OfficialName":"Rush Hill","ParentVolcanoId":"ak264","ParentVolcano":"St. Paul Island","AgeClass":"SuspPleist","AgeSource":"Rush Hill is definitely Quaternary. Winer (2001) and Winer and others (2004) state that it is one of the younger vents on St. Paul Island.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Cinder cone","NvewsThreat":null,"Description":"From Winer, 2001: \"A large eruptive center on the west end of St. Paul, Rush Hill is the highest point on the island (665'). The multiple nested pyroclastic cones of Rush Hill indicate a complicated eruptive history. The cone complex is breached to the north and west where lava flows extend to the coast. Lava is dark gray olivine basalt and tephrite. Vesicular spatter form the summit of Rush Hill (SP98-78) contains a crustal xenolith.\"","NameOrigin":"Rush Hill was probably named by Joseph Stanley-Brown, naturalist, in 1891, for the U.S. Revenue Cutter, Richard Rush, during fur-seal investigations of the Pribilof Islands 1891 by the U.S. Treasury Department (Orth, 1971)."},{"VolcanoId":"ak245","Vnum":null,"Volcano":"Seemalik Butte","OfficialName":"Seemalik Butte","ParentVolcanoId":"ak204","ParentVolcano":"Nunivak Island","AgeClass":null,"AgeSource":"Tertiary!","Composition":"basalt","IsMonitored":false,"VolcanoType":"Stratovolcano","NvewsThreat":null,"Description":null,"NameOrigin":"\"Seemalik Butte\" is a Cup'ik name, reported by the U.S. Coast and Geodetic Survey in 1949 (Orth, 1971)."},{"VolcanoId":"ak250","Vnum":null,"Volcano":"Shell Mtn","OfficialName":"Shell Mountain","ParentVolcanoId":"ak90","ParentVolcano":"Edgecumbe","AgeClass":"SuspPleist","AgeSource":"Riehle and others (1989, I-1983) say Shell Mountain deposits are Pleistocene.","Composition":"andesite","IsMonitored":false,"VolcanoType":"Stratovolcano","NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak258","Vnum":null,"Volcano":"South Twin","OfficialName":"South Twin","ParentVolcanoId":"ak124","ParentVolcano":"Iliamna","AgeClass":"SuspHolo","AgeSource":"Shown as Q in OF 99-373 (Miller and others, 1999).","Composition":null,"IsMonitored":false,"VolcanoType":"Former Dome","NvewsThreat":null,"Description":null,"NameOrigin":"\"South Twin\" is a lcaol descriptive name, published by the U.S. Coast and Geodetic Survey in 1912 (Orth, 1971)."},{"VolcanoId":"ak266","Vnum":null,"Volcano":"Stephens Hill","OfficialName":"Stephens Hill","ParentVolcanoId":"ak262","ParentVolcano":"St. Michael","AgeClass":"SuspHolo","AgeSource":"Mukasa and others (2007) produced several 40Ar/39Ar age dates for the St. Michael volcanic field: from 0.80 +/-0.03 Ma, to (at Crater Mountain) 0.37+/-0.02 Ma). Aboriginal legends suggest that that most recent eruptions were 2000-3000 years ago.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Cone","NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak283","Vnum":null,"Volcano":"Three-quarter cone","OfficialName":null,"ParentVolcanoId":"ak248","ParentVolcano":"Semisopochnoi","AgeClass":"SuspPleist","AgeSource":"Coats (1959) states that these volcanics are older than the last glaciation, possibly even as old as the late Tertiary.","Composition":"mafic","IsMonitored":false,"VolcanoType":"Stratovolcano","NvewsThreat":null,"Description":null,"NameOrigin":"R.R. Coats named Threequarter Cone in 1950, \"because part of the cone has been removed in the formation of the caldera\" (Orth, 1971)."},{"VolcanoId":"ak308","Vnum":null,"Volcano":"Vulcan Dome","OfficialName":null,"ParentVolcanoId":"ak14","ParentVolcano":"Aniakchak","AgeClass":null,"AgeSource":null,"Composition":null,"IsMonitored":false,"VolcanoType":"Lava dome","NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak317","Vnum":null,"Volcano":"West Dome","OfficialName":null,"ParentVolcanoId":"ak14","ParentVolcano":"Aniakchak","AgeClass":null,"AgeSource":null,"Composition":null,"IsMonitored":false,"VolcanoType":"Lava dome","NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak323","Vnum":null,"Volcano":"White Fish Lake","OfficialName":"White Fish Lake","ParentVolcanoId":"ak95","ParentVolcano":"Espenberg","AgeClass":"Pleistocene","AgeSource":"Beget and others, 1996: Whitefish maar may be 100-200,000 years old (Hopkins, 1988; Beget and others,1991).","Composition":"basalt","IsMonitored":false,"VolcanoType":"Maar","NvewsThreat":null,"Description":null,"NameOrigin":"\"White Fish Lake\" is a local name reported by the U.S. Geological Survey in 1950 (Orth, 1971)."},{"VolcanoId":"ak123","Vnum":null,"Volcano":"Ikathiwik Crater","OfficialName":"Ikathiwik Crater","ParentVolcanoId":"ak204","ParentVolcano":"Nunivak Island","AgeClass":"Pleistocene","AgeSource":"Hoare and others (1968) show Ikathiwik Crater as Quaternary.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Cone","NvewsThreat":null,"Description":null,"NameOrigin":"\"Ikathiwik Crater\" is a Cup'ik name obtained in 1949 by the U.S. Coast and Geodetic Survey (Orth, 1971)."},{"VolcanoId":"ak170","Vnum":null,"Volcano":"Kookoolit Hill","OfficialName":null,"ParentVolcanoId":"ak169","ParentVolcano":"Kookooligit Mountains","AgeClass":"Pleistocene","AgeSource":"Patton and Csejtey (1980) published 5 K-Ar age dates for Kookooligit lava flows, ranging from 1.46 Ma to 0.24 Ma. Mukasa and others (2007) have a single 40Ar/39Ar age date of 1.22 +/-0.02 Ma.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Cone","NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak30","Vnum":null,"Volcano":"Bogoslof Hill","OfficialName":"Bogoslof Hill","ParentVolcanoId":"ak264","ParentVolcano":"St. Paul Island","AgeClass":"Pleistocene","AgeSource":"Winer and others (2004) report a 40Ar/39Ar age dates of 40 +/- 20 ka and 330 +/- 40 ka for Bogoslof Hill.","Composition":"mafic","IsMonitored":false,"VolcanoType":"Cone","NvewsThreat":null,"Description":"From Winer, 2001: \"Bogoslof Hill volcanic complex - A polygenetic shield volcano with a complex eruptive history. Bogoslof Hill is the source of the most volumnious lava flows forming the central highland. Pahoehoe lava flows are surface- and tube-fed. Lava tubes are exposed on the NW, W, and SW flanks of Bogoslof Hill. Rifts trending E-W across Bogoslof Hill are partially covered by younger lava flows. Some Bogoslof lavas are conspicously plagioclase-rich (~30 modal % plagioclase). The most extensive of the Bogoslof flows, a trachybasalt with abundant very fine groundmass plagioclase, has many blocky outcrops interpreted as tumuli, lava rises, and pop-ups. Most BHVC lavas are tephrites.\"","NameOrigin":"Bogoslof Hill's name is reported by Elliott (1881) as \"Boga Slov,\" or \"word of God\" (Orth, 1971)."},{"VolcanoId":"ak318","Vnum":null,"Volcano":"West Hill 1","OfficialName":"West Hill","ParentVolcanoId":"ak262","ParentVolcano":"St. Michael","AgeClass":"SuspHolo","AgeSource":"Mukasa and others (2007) produced several 40Ar/39Ar age dates for the St. Michael volcanic field: from 0.80 +/-0.03 Ma, to (at Crater Mountain) 0.37+/-0.02 Ma). Aboriginal legends suggest that that most recent eruptions were 2000-3000 years ago.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Cone","NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak76","Vnum":null,"Volcano":"Devil Mtn","OfficialName":"Devil Mountain","ParentVolcanoId":"ak95","ParentVolcano":"Espenberg","AgeClass":"","AgeSource":"Unknown","Composition":"basalt","IsMonitored":false,"VolcanoType":"Shield volcano","NvewsThreat":null,"Description":null,"NameOrigin":"Devil Mountain was named \"Teufelsberg\" (German for \"Devils Mountain\" by Lt. Otto van Kotzebue in 1816 (Orth, 1971)."},{"VolcanoId":"ak235","Vnum":null,"Volcano":"Round Head","OfficialName":"Round Head","ParentVolcanoId":"ak144","ParentVolcano":"Kanaga","AgeClass":"SuspPleist","AgeSource":"Coats (1956) believes this volcano is Tertiary to Quaternary.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Cone","NvewsThreat":null,"Description":null,"NameOrigin":"\"Round Head\" was named in 1934 by members of the U.S. Navy Aleutian Island Survey Expedition, because of its shape (Orth, 1971)."},{"VolcanoId":"ak270","Vnum":null,"Volcano":"Suemez Island","OfficialName":null,"ParentVolcanoId":"ak284","ParentVolcano":"Tlevak Strait volcanic field","AgeClass":"SuspHolo","AgeSource":"Although Eberlein and others (1983) suspect Quaternary or Holocene age for the Tlevak Strait-Suemez Island volcanics, Brew and others (1996) map them as Quaternary-Tertiary.","Composition":"mixed","IsMonitored":false,"VolcanoType":"Vents, domes, and flows","NvewsThreat":"Very Low Threat","Description":"Devonian and Silurian sedimentary packages on Suemez Island are overlain by Quaternary rhyolite and trachyte vents, domes, and flows. Many of the vents are located close to Cape Felix, on the southwest portion of Suemez Island. (Kate Bull, personal communication, 2009).","NameOrigin":"\"Suemez Island volcanic area\" is an informal name, after Suemez Island, where the vents are located. \"Suemez Island\" is a Spanish name given in 1775-79 by Don Juan de la Bodega y Quadra and Francisco Antonio Maurelle as \"Isla Suemez.\" This island was shows as \"Guemes\" by D.A. Galiano (1802) (Orth, 1971)."},{"VolcanoId":"ak57","Vnum":null,"Volcano":"Cone B","OfficialName":null,"ParentVolcanoId":"ak206","ParentVolcano":"Okmok","AgeClass":"Historical","AgeSource":"Historical 1817 eruption.","Composition":"mafic","IsMonitored":false,"VolcanoType":"Cone","NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak58","Vnum":null,"Volcano":"Cone C","OfficialName":null,"ParentVolcanoId":"ak206","ParentVolcano":"Okmok","AgeClass":"Holocene","AgeSource":"This cone is of Holocene age.","Composition":"mafic","IsMonitored":false,"VolcanoType":"Cone","NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak59","Vnum":null,"Volcano":"Cone D","OfficialName":null,"ParentVolcanoId":"ak206","ParentVolcano":"Okmok","AgeClass":"Holocene","AgeSource":"This cone is Holocene age.","Composition":"mafic","IsMonitored":false,"VolcanoType":"Cone","NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak60","Vnum":null,"Volcano":"Cone E","OfficialName":null,"ParentVolcanoId":"ak206","ParentVolcano":"Okmok","AgeClass":"Holocene","AgeSource":"This cone is of Holocene age.","Composition":"mafic","IsMonitored":false,"VolcanoType":"Cone","NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak61","Vnum":null,"Volcano":"Cone F","OfficialName":null,"ParentVolcanoId":"ak206","ParentVolcano":"Okmok","AgeClass":"Holocene","AgeSource":"This cone is of Holocene age.","Composition":"mafic","IsMonitored":false,"VolcanoType":"Cone","NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak62","Vnum":null,"Volcano":"Cone G","OfficialName":null,"ParentVolcanoId":"ak206","ParentVolcano":"Okmok","AgeClass":"Holocene","AgeSource":"This cone is of Holocene age.","Composition":"mafic","IsMonitored":false,"VolcanoType":"Cone","NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak63","Vnum":null,"Volcano":"Cone H","OfficialName":null,"ParentVolcanoId":"ak206","ParentVolcano":"Okmok","AgeClass":"Holocene","AgeSource":"This cone is of Holocene age.","Composition":"mafic","IsMonitored":false,"VolcanoType":"Cone","NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak65","Vnum":null,"Volcano":"Cone I","OfficialName":null,"ParentVolcanoId":"ak206","ParentVolcano":"Okmok","AgeClass":"Holocene","AgeSource":"This cone is of presumed Holocene age.","Composition":null,"IsMonitored":false,"VolcanoType":"Cone","NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak66","Vnum":null,"Volcano":"Cone J","OfficialName":null,"ParentVolcanoId":"ak206","ParentVolcano":"Okmok","AgeClass":"Holocene","AgeSource":"This cone is of Holocene age.","Composition":"mafic","IsMonitored":false,"VolcanoType":"Cone","NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak1","Vnum":null,"Volcano":"1931 Crater","OfficialName":null,"ParentVolcanoId":"ak14","ParentVolcano":"Aniakchak","AgeClass":"Historical","AgeSource":"Historical eruption.","Composition":null,"IsMonitored":false,"VolcanoType":"Tephra cone with lava flow","NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak178","Vnum":null,"Volcano":"Lava Fork","OfficialName":null,"ParentVolcanoId":"ak136","ParentVolcano":"Iskut-Unuk volcanic field","AgeClass":"Historical","AgeSource":"James Baichtal has a 14C date for the Unuk River lava flow of 95 yBP.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Monogenetic cones and small stratovolcanoes","NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak208","Vnum":null,"Volcano":"Painted Peak","OfficialName":"Painted Peak","ParentVolcanoId":"ak22","ParentVolcano":"Behm Canal volcanic field","AgeClass":"SuspPleist","AgeSource":"Berg and others (1988): K-Ar ages of Painted Peak show volcanism at about 5 Ma and between 1 and 0.4 Ma.","Composition":"mafic","IsMonitored":false,"VolcanoType":"Tuff ring","NvewsThreat":null,"Description":null,"NameOrigin":"The U.S. Forest Service named this mountain \"Painted Peak\" in 1923 (Orth, 1971)."},{"VolcanoId":"ak220","Vnum":null,"Volcano":"Princess Bay cone","OfficialName":null,"ParentVolcanoId":"ak22","ParentVolcano":"Behm Canal volcanic field","AgeClass":"SuspPleist","AgeSource":"Youngest flows possibly ~0.5 my (W\u0026K).","Composition":"mafic","IsMonitored":false,"VolcanoType":"Cinder cone","NvewsThreat":null,"Description":null,"NameOrigin":"\"Princess Bay cone\" is an informal name, after the nearby Princess Bay. Princess Bay was named by local navigators, prior to 1904 (Orth, 1971)."},{"VolcanoId":"ak136","Vnum":320090,"Volcano":"Iskut-Unuk volcanic field","OfficialName":null,"ParentVolcanoId":"ak136","ParentVolcano":"Iskut-Unuk volcanic field","AgeClass":"Historical","AgeSource":"James Baichtal has a 14C date for the Unuk River lava flow of 95 yBP.","Composition":"basalt","IsMonitored":false,"VolcanoType":"volcanic field","NvewsThreat":null,"Description":"   The Iskut-Unuk River volcanic field is largely located in Canada.  They are included here because flows from the Lava Fork valley flow south over the Alaskan border and into Alaska.\r\n   From Wood and Kienle (1990): \"The Iskut River cones comprise a group of six small basaltic centers in the southern part of the Stikine Volcanic Belt.  The largest, Iskut Canyon Cone - a stratovolcano ~1 km across and 200 m high - is exposed on the steep southern slope of Iskut valley near its junction with Forrest Kerr Creek.  This cone is the source of at least 10 thick lava flows which initially dammed Iskut River and are now exposed in a box canyon extending ~20 km downstream from the cone.  The flows are divided into two groups separated by an erosion surface.  A lower group of dark-colored alkali basalt flows predates wood that gave a C14 date of 8,780 yr BP.  Wood from a gravel lens in an upper group of light-colored flows yielded a C14 date of 3,660 yr BP.  Drilling to assess the hydroelectric potential of the canyon revealed that the subaerial flows are underlain by hyaloclastite resting on pre-eruption river gravel.\r\n   \"Cinder Mountain, a partly eroded composite cone at the head of Snippaker Creek, is the source of a basalt flow that extends 4 km north into Copper King Creek, where it rests on an alpine moraine.  The edifice, which rises ~300 m above the surface of surrounding alpine glaciers, consists mostly of pillow lava and hyaloclastite breccia.  These ice-contact deposits probably formed during a period of Holocene glacial advance when alpine glaciers extended to the limit of their present trimlines.  The initial accumulation of hyaloclastite in a subglacial meltwater basin was followed by failure of the ice dam and eruption of the subaerial flow which entered Copper King valley after the meltwater had drained.\r\n   \"An isolated pile of subaerial basalt flows and associated pillow lava rest on varved clay and till in King Creek.  This material probably originated from a small subglacial center that was roughly coeval with Cinder Mountain.\r\n   \"A pyroclastic cone ~300 m high (Snippaker Creek Cone) near the west flank of Cinder Mountain is the source of a narrow, levee-bounded flow that descended Snippaker valley for ~20 km, almost to its junction with Iskut valley.\r\n   \"About 1 kilometer north of the Alaska border, Unuk River valley is occupied by a blocky lava field that has forced the river against its eastern bank.  The source of this flow is a cluster of dissected cinder cones in Canyon Creek, a small steep-sided tributary valley on the east side of Unuk River valley.\r\n   \"The flow in Lava Fork valley is probably the youngest in Canada.  It issued from a vent near the crest of a ridge on the north side of the valley, where ropy pahoehoe lava is associated with irregular mounds of fire-fountain deposits, open lava tubes, and steep-walled lava troughs.  No cone is present in the vent area, but thick deposits of loose tephra still cling to ledges on the surrounding granite peaks and form lenses within some of the adjacent glaciers.  From the vent, at an elevation of ~1,200 m, the flows cascade down \u003e1,000 m of steep granite cliffs to the broad valley of Lava Fork, where two small lakes are ponded above the flow.  The main flow extends south along Lava Fork for 12 km to Blue River valley in Alaska, and along Blue River valley for another 9 km, where it spreads into a broad terminal lobe on the flat alluvial plain of Unuk River.  Several successive overlapping lava flows with varying degrees of reforestation suggest intermittent eruptive activity separated by quiescent periods.  Carbonized wood on one of the older flows yielded a C14 date of 360 yr BP.\r\n   \"All analyzed samples of lava from the Iskut cones are alkali olivine basalt.\"","NameOrigin":"\"Iskut-Unuk volcanic field\" is an informal name, after the nearby rivers."},{"VolcanoId":"ak289","Vnum":null,"Volcano":"Trident I","OfficialName":null,"ParentVolcanoId":"ak288","ParentVolcano":"Trident","AgeClass":"Pleistocene","AgeSource":"Hildreth and others (2003) give K-Ar and 40Ar/39Ar age dates in the 73-58 ka range, and state that Trident 1 has had no Holocene eruptions.","Composition":"andesite","IsMonitored":false,"VolcanoType":null,"NvewsThreat":null,"Description":null,"NameOrigin":"\"Trident I\" is an informal name."},{"VolcanoId":"ak259","Vnum":null,"Volcano":"Southwest Trident","OfficialName":null,"ParentVolcanoId":"ak288","ParentVolcano":"Trident","AgeClass":"Historical","AgeSource":"Historical eruptions (1953-1974).","Composition":null,"IsMonitored":false,"VolcanoType":null,"NvewsThreat":null,"Description":null,"NameOrigin":"\"Southwest Trident\" is an informal name."},{"VolcanoId":"ak254","Vnum":null,"Volcano":"Sirius Point","OfficialName":"Sirius Point","ParentVolcanoId":"ak161","ParentVolcano":"Kiska","AgeClass":"Historical","AgeSource":"Historical eruptions.","Composition":"unknown","IsMonitored":false,"VolcanoType":null,"NvewsThreat":null,"Description":null,"NameOrigin":"The U.S. Navy Hydrographic Department named Sirius Point in 1936, for the U.S.S. Sirius, supply ship of the Navy Aleutian Island Survey Expedition of 1935 (Orth, 1971)."},{"VolcanoId":"ak9","Vnum":null,"Volcano":"Amchixtam Chaxsxii","OfficialName":null,"ParentVolcanoId":"ak9","ParentVolcano":"Amchixtam Chaxsxii","AgeClass":"SuspHolo","AgeSource":"Because Amchixtam Chaxsxii has fresh morphology, Jennifer Reynolds (personal commun., 2004) believes it is of Holocene age.","Composition":"unknown","IsMonitored":false,"VolcanoType":"Submarine volcano","NvewsThreat":"","Description":"   Amchixtam Chaxsxii is a submarine, polygenetic cone that rises about 580 m from the seafloor and is about 115 m below current sealevel.  The base of Amchixtam Chaxsxii is about 4 km across (Jennifer Reynolds, 2004, personal communication.)","NameOrigin":"\"Amchixtam Chaxsxii\" is from the Atka dialect of Unangam Tunuu langauge, and was suggested by the local Unangax community as a name for the submarine volcano."},{"VolcanoId":"ak55","Vnum":null,"Volcano":"Cone 3601","OfficialName":null,"ParentVolcanoId":"ak55","ParentVolcano":"Cone 3601","AgeClass":"Pleistocene","AgeSource":"Hildreth and others (2004) have dated Cone 3601 lavas to 132 +/- 27 ka.","Composition":"mafic","IsMonitored":false,"VolcanoType":"Modest mafic stratocone","NvewsThreat":null,"Description":"   This feature is part of the Savonoski River Cluster of volcanoes, as defined by Hildreth and others (2004).  From Hildreth and others (2004): \"The largest of the mafic cones [in the Savonoski River volcano cluster] (54% SiO2), 2.5 km wide with 850 m of relief, is banked against a basement ridge just north of the snout of Hook Glacier.  It consists of blocky and columnar lavas (132 +/- 27 ka), breccia sheets, and stratified scoria. Products contain orthopyroxene, magnetite, and abundant small plagioclase phenocrysts.\"","NameOrigin":"Cone 3601 is an informal name given by Hildreth and others (2004)."},{"VolcanoId":"ak54","Vnum":null,"Volcano":"Cone 3110","OfficialName":null,"ParentVolcanoId":"ak54","ParentVolcano":"Cone 3110","AgeClass":"Pleistocene","AgeSource":"Hildreth and others (2004) have dated Cone 3110 lavas to 235 +/- 30 ka.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Modest mafic stratocone","NvewsThreat":null,"Description":"   This feature is part of the Savonoski River Cluster of volcanoes, as defined by Hildreth and others (2004).  From Hildreth and others (2004): \"Cone 3110 is a basaltic pile (51% SiO2) about 2 km wide with 675 m of relief that lies a few km NW of Cone 3601.  Partly erupted englacially, it consists mostly of massive to sheeted glassy breccia and coarse stratified scoria that dip chaotically and enclose channel fillings of convolutedly columnar glassy lava.  The upper third of the cone (235 +/- 30 ka) is coherent lava, columnar to chunky jointed.  Products have abundant plagioclase, clinopyroxene, and olivine, with minor orthopyroxene.\"","NameOrigin":"Cone 3110 is an informal name given by Hildreth and others (2004)."},{"VolcanoId":"ak165","Vnum":null,"Volcano":"Knob 1000","OfficialName":null,"ParentVolcanoId":"ak165","ParentVolcano":"Knob 1000","AgeClass":"SuspPleist","AgeSource":"Hildreth and others (2004)?","Composition":"basalt","IsMonitored":false,"VolcanoType":"Glaciated remnant; probable vent","NvewsThreat":null,"Description":"   This feature is part of the Savonoski River Cluster of volcanoes, as defined by Hildreth and others (2004).  From Hildreth and others (2004): \"Knob 1000 is a basaltic remnant (52% SiO2) only 400 m across, on the south bank of the Savonoski River about 2 km NNW of Cone 3110.  The 100-m thick remnant forms a glacially scoured conical knoll that consists of finely vesicular lava (variously hackly, chunky, or sheet jointed) and a subequal proportion of crudely layered breccia and sintered scoria-rich rubble.  Stratification and the abundance of coarse scoria indicate a local vent, and the textures and jointing suggest ice-contact emplacement.  Products contain phenocrysts of clinopyroxene, olivine, and abundant small plagioclase, and minor magnetite.  We first assumed the knob to be an erosional outlier of Cone 3110, but significant differences in K2O, TiO2, and Al2O3 support the likelihood of independent vents and magma batches.\"","NameOrigin":"\"Knob 1000\" is an informal name given by Hildreth and others (2004)."},{"VolcanoId":"ak134","Vnum":null,"Volcano":"Iron Trig cone","OfficialName":null,"ParentVolcanoId":"ak134","ParentVolcano":"Iron Trig cone","AgeClass":"Pleistocene","AgeSource":"Hildreth and others (2004) have dated lava from Iron Trig cone to 88 +/- 27 ka.","Composition":"mafic","IsMonitored":false,"VolcanoType":"Scoria cone and lava-flow apron","NvewsThreat":null,"Description":"   This feature is part of the Savonoski River Cluster of volcanoes, as defined by Hildreth and others (2004).  From Hildreth and others (2004): \"Iron Trig Cone (Peak 4260) is a mafic scoria cone (53-54% SiO2) atop the basement divide between the Savonoski and Kamishak Rivers, 50 km NE of Mount Katmai and 25 km north of Mount Denison.  The glaciated cone, 800 m across with 250 m relief, consists of stratified scoria, agglutinate, and thin lava sheets that are cut by a small intrusion exposed on the west face.  Ejecta and lava contain phenocrysts of plagioclase, olivine, clinopyroxene, and magnetite.  A lava-flow apron (88 +/- 27 ka) descends the WSW flank to an elevation 300 m lower than the cone, condensing into a single flow 20 m thick at its eroded terminus, 2 km from the cone.\"","NameOrigin":"\"Iron Trig cone\" is an informal name given by Hildreth and others (2004)."},{"VolcanoId":"ak228","Vnum":null,"Volcano":"Rainbow River cone","OfficialName":null,"ParentVolcanoId":"ak228","ParentVolcano":"Rainbow River cone","AgeClass":"Pleistocene","AgeSource":"Hildreth and others (2004) have dated lava from Rainbow River cone to 390 +/- 39 ka.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Small mafic stratocone and lava-flow apron","NvewsThreat":null,"Description":"   This feature is part of the Savonoski River Cluster of volcanoes, as defined by Hildreth and others (2004).  From Hildreth and others (2004): \"Rainbow River Cone (Peak 3980) is a small basaltic volcano (51.8-53% SiO2) perched on a basement ridge east of Rainbow River, 15 km NW of Mount Denison.  The glacially sculpted cone, 1 km wide with 330 m relief, consists of radially dipping stacks of thin lavas and breccia sheets intercalated with scoria falls, well exposed on bounding cliffs, cut by numerous dikes, and gutted by a northerly cirque.  Lavas and ejecta contain phenocrysts of plagioclase, orthopyroxene, clinopyroxene, olivine, and Fe-Ti oxides.  An ice-scoured lava plateau (390 +/- 39 ka) extends 1 km SE from the cone.\"","NameOrigin":"\"Rainbow River cone\" is an informal name, after the nearby Rainbow River given by Hildreth and others (2004). The Rainbow River was named by R.H. Sargent's party in 1923 \"because six rainbows were seen there\" (Orth, 1971)."},{"VolcanoId":"ak102","Vnum":null,"Volcano":"Folsoms Bluff","OfficialName":null,"ParentVolcanoId":"ak102","ParentVolcano":"Folsoms Bluff","AgeClass":"SuspPleist","AgeSource":"Hildreth and others (2004) suggest that Folsom's Bluff is younger than the three ridge-capping members of the Saddlehorn Creek Cluster. Hildreth and others (2003) map Folsoms Bluff as QTm, however.","Composition":"andesite","IsMonitored":false,"VolcanoType":"Lava and ejecta of glaciated vent complex","NvewsThreat":null,"Description":"   This feature is part of the Saddlehorn Creek Cluster of volcanoes, as defined by Hildreth and others (2004).  From Hildreth and others (2004): \"Folsoms Bluff (Knob 3800), an inhomogenously andesitic (55-60% SiO2) funnel-shaped vent complex, is a multi-lobate glassy lava mass 500 m wide and 200 m high that makes up part of the canyon wall just 2 km east of Fenners Saddlehorn.  Marked by steep flow foliation and several sets of inclined, subhorizontal, or steeply curving glassy columns indicative of ice-contact emplacement, the lava has a brecciated base that overlies 8 to 15 m of stratified, poorly sorted proximal fallout, which includes scoria bombs to 75 cm and blocks of basement granitoid to 30 cm.  This basal fallout drapes a steep paleoslope and extends uphill into a mass of agglutinated lithic-rich rubble more than 20 m thick, probably vent fill largely concealed by the overlying lava.  All lithologies contain abundant small plagioclase phenocrysts as well as olivine, clinopyroxene, orthopyroxene, and magnetite.  Its canyon-wall setting and eruptive facies relations suggest that, like Fenners Saddlehorn nearby, this undated glassy unit is younger than the three ridge-capping members of the cluster.\"","NameOrigin":"\"Folsoms Bluff\" is an informal name given by Hildreth and others (2004)."},{"VolcanoId":"ak21","Vnum":null,"Volcano":"Basalt of Gertrude Creek","OfficialName":null,"ParentVolcanoId":"ak21","ParentVolcano":"Basalt of Gertrude Creek","AgeClass":"Pleistocene","AgeSource":"Hildreth and others (2004) have a 40Ar/39Ar plateau age of 500 +/- 15 ka for Basalt of Gertrude Creek.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Ice-scoured scoria cone and lava apron","NvewsThreat":null,"Description":"   This feature is part of the Saddlehorn Creek Cluster of volcanoes, as defined by Hildreth and others (2004).  From Hildreth and others (2004): \"Basalt of Gertrude Creek makes up a 1-km-wide remnant of an ejecta cone and lava-flow apron that form a glacially smoothed domical swell about 5 km NE of Becharof Lake, near the trace of the Bruin Bay Fault (Riehle and others, 1993).  Surviving outcrop has about 60 m of gentle relief and includes a 200-m-wide degraded crater now only 5 to 8 m deep, rimmed by brick-red scoria blocks and sheets of blobby agglutinate that are broken and frost-heaved into slabs.  Outside the rim is a massive to finely vesicular, basaltic lava.  The subalkaline high-alumina basalt (49.8% SiO2, 6.8% MgO) contains abundant small phenocrysts of olivine, clinopyroxene, and plagioclase, and inclusions (in olivine) of Cr-spinel.  A slab of holocrystalline lava near the north rim gave a 40Ar/39Ar plateau age of 500 +/- 15 ka (Hildreth and others, 2003).\"","NameOrigin":"\"Basalt of Gertrude Creek\" is an informal name applied to the volcanic vent near Gertrude Creek, given by Hildreth and others (2004). Gertrude Creek is a local name, reported to the U.S. Geological Survey in 1952 (Orth, 1971)."},{"VolcanoId":"ak24","Vnum":null,"Volcano":"Black Bluffs","OfficialName":"Black Bluffs","ParentVolcanoId":"ak264","ParentVolcano":"St. Paul Island","AgeClass":"SuspPleist","AgeSource":"Winer (2001) describes Black Bluffs as Quaternary.","Composition":"mafic","IsMonitored":false,"VolcanoType":"Tuff cone","NvewsThreat":null,"Description":"From Winer, 2001: \"A vertical section of the Black Bluffs emergent tuff/cinder cone is exposed on the coast east of the village of St. Paul. The lower part of the cone, near sea level, is grey-brown and red-brown, well-consolidated, thinly-stratified tuff composed of rounded lapilli in an ashy matrix; it contains accidental blocks of friable grey mudstone and has bedding plane sags related to block and bomb impacts. Up section the composition changes abruptly to black, crudely-stratified scoria with block-rich layers. The face of Black Bluffs is faulted with offsets as great as 2.5 m.\"","NameOrigin":"Black Bluffs was named in 1875 by the U.S. Coast and Geodetic Survey (Orth, 1971)."},{"VolcanoId":"ak68","Vnum":null,"Volcano":"Crater Hill, east summit vent","OfficialName":"Crater Hill","ParentVolcanoId":"ak264","ParentVolcano":"St. Paul Island","AgeClass":"Pleistocene","AgeSource":"Winer and others (2004) obtained a 40Ar/39Ar age date of 360 +/- 80 ka, for a lava flow erupted from Crater Hill.","Composition":"mafic","IsMonitored":false,"VolcanoType":"Cinder Cone","NvewsThreat":null,"Description":"From Winer 2001: \"Crater Hill pyroclastic cone and associated lava flow - The upper Crater Hill cone is armored with spatter and has a sharp edged crater rim that appears to have been truncated by a violent explosion that may have reamed out the inner wall of the cone. A lake and two spatter cones are contained within the crater. Welded spatter on the crater rim contains both granitic and ultramafic xenoliths. A tongue of olivine-basalt lava flows northward from the breached scoria cone. Winer and others, 2004 days age of one lava from this area is 360 +/- 80 ka.\"","NameOrigin":"Crater Hill's name was published in 1875 by the U.S. Coast and Geodetic Survey, perhaps obtained from Elliott (1881) who was on St. Paul Island in 1873-74 (Orth, 1971)."},{"VolcanoId":"ak118","Vnum":null,"Volcano":"Hill 404","OfficialName":null,"ParentVolcanoId":"ak264","ParentVolcano":"St. Paul Island","AgeClass":"SuspPleist","AgeSource":"Winer (2001) describes Hill 404 as Quaternary.","Composition":"mafic","IsMonitored":false,"VolcanoType":"Cinder cone","NvewsThreat":null,"Description":"From Winer, 2001: \"Hill 404 is a simple breached cinder cone with a small lava flow; the flow may be partially buried by younger flows from other centers\"","NameOrigin":"\"Hill 404\" is an informal name, referring to a hill that is 404 feet high."},{"VolcanoId":"ak120","Vnum":null,"Volcano":"Hutchinson Hill","OfficialName":"Hutchinson Hill","ParentVolcanoId":"ak264","ParentVolcano":"St. Paul Island","AgeClass":"Pleistocene","AgeSource":"Winer and others (2004) report a 40Ar/39Ar age date of 80 +/- 50 ka for Hutchinson Hill.","Composition":"mafic","IsMonitored":false,"VolcanoType":"Shield volcano","NvewsThreat":null,"Description":"From Winer, 2001: \"Hutchison Hill is constructed of scoria, welded spatter, and thin (\u003c1 m) lava flows. Basalts of the Hutchison Hill field are plagioclase-rich (~22 modal%). The Hutchison Hill cone and lava field formed an island that has since connected to the main island by a tombolo.\"","NameOrigin":"\"Hutchinson Hill\" was named for Hayward Malcolm Hutchinson, one of the first Americans to reach Sitka in 1867. He bought the property of the Russian American Company forming Hutchinson, Kohl, and Company. In 1872, it, in turn, was bought by the Alaska Commercial Company, which had secured the lease of the fur-seal rookeries of the Pribilof Islands. The name \"Hutchinson Hill\" is shown on Elliott's 1873-74 map of Saint Paul Island (Orth, 1971)."},{"VolcanoId":"ak233","Vnum":null,"Volcano":"Ridge Wall crater 1","OfficialName":"Ridge Wall","ParentVolcanoId":"ak264","ParentVolcano":"St. Paul Island","AgeClass":"SuspPleist","AgeSource":"Winer (2001) considered Ridge Wall Quaternary.","Composition":"mafic","IsMonitored":false,"VolcanoType":"Cinder cone","NvewsThreat":null,"Description":"From Winer, 2001: \"Ridge Wall is a complex breached cinder cone with multiple aligned vents and an associated lava flow. The lava flow has moved a large portion of the cone; as much as 15 m of cone material rests on the lava flow exposed in vertical section in the sea cliff. The basalt in the flow is dark grey and vitrophyric with olivine phenocrysts as large as 5 mm. Ridge Wall's pyroclastic deposite includes a large portion of unwelded, very glassy ribbon and cowdung bombs with colors ranging from brown to red to blue-black.\"","NameOrigin":"\"Ridge Wall\" is a local name, reported in 1881 by Elliott (Orth, 1971)."},{"VolcanoId":"ak64","Vnum":null,"Volcano":"Cone Hill","OfficialName":"Cone Hill","ParentVolcanoId":"ak264","ParentVolcano":"St. Paul Island","AgeClass":"Pleistocene","AgeSource":"Winer and others (2004) report 40Ar/39Ar age dates for the Cone Hill complex of 120 +/- 40 ka and 180 +/- 40 ka.","Composition":"mafic","IsMonitored":false,"VolcanoType":"Fissure vent","NvewsThreat":null,"Description":null,"NameOrigin":"Cone Hill's name was published in 1875 by the U.S. Coast and Geodetic Survey. The name was possibly obtained from Helliott (1881) who was there in 1873-74 (Orth, 1971)."},{"VolcanoId":"ak291","Vnum":null,"Volcano":"Turquoise cone","OfficialName":null,"ParentVolcanoId":"ak100","ParentVolcano":"Fisher","AgeClass":"Holocene","AgeSource":"Stelling and others (2005) report 14C dates of Turquoise Cone dacite as 5120 years.","Composition":"mixed","IsMonitored":false,"VolcanoType":null,"NvewsThreat":null,"Description":"From Stelling and others, 2005: \"The eruptive products of Turquoise Cone are compositionally diverse, ranging from pl+ol+cpx high-alumina basalt to sparsely plagioclase-phyric dacite. The oldest deposits from Turquoise Cone are the most mafic (47 wt.% SiO2), whereas the last eruptions from this vent are the most silicic (66 wt.% SiO2). The present-day amphitheater-like form of Turquoise Cone resulted from a significant collapse event. Through geometric extrapolation of existing deposits and their inclinations, the pre-collapse volume of Turquoise Cone is estimated to have been ~3 km, and slighty more than half of that volume has been removed. No deposits from the collapse event have been recognized, and we believe that they have been buried by subsequent eruptions from Turquoise Cone and other intracaldera vents. We are thus unable to constrain the trigger or structure of the collapse.\"","NameOrigin":null},{"VolcanoId":"ak199","Vnum":null,"Volcano":"Neptune","OfficialName":null,"ParentVolcanoId":"ak100","ParentVolcano":"Fisher","AgeClass":"SuspHolo","AgeSource":"Stelling and others (2005) suggest a Holocene age for Neptune cone.","Composition":"unknown","IsMonitored":false,"VolcanoType":null,"NvewsThreat":null,"Description":"From Stelling and others, 2005: \"An isolated polygenetic stratocone outside the caldera to the northwest, here named Neptune Cone (\"NC\") lacks deposits from the caldera-forming eruption, suggesting a Holocene age. The most recent eruption from this cone was a fissure eruption that produced a ~4 km-long linear ridge of basaltic (49 wt.% SiO2, Mg#=0.57), scoria and spatter, extending to the north of the cone (\"arm\" extending from Neptune Cone).\"","NameOrigin":null},{"VolcanoId":"ak141","Vnum":null,"Volcano":"Jumbo Dome","OfficialName":"Jumbo Dome","ParentVolcanoId":"ak141","ParentVolcano":"Jumbo Dome","AgeClass":"Pleistocene","AgeSource":"40Ar/39Ar dating by Athey and others (2006) yields an age for Jumbo Dome of 1.026 +/- 0.057 Ma.","Composition":null,"IsMonitored":false,"VolcanoType":"A large cylindrical plug of hornblende andesite","NvewsThreat":null,"Description":"   From Albanese (1980): \"Jumbo Dome is a large cylindrical plug of hornblende andesite 1.6 km long, 1.3 km wide, and 500 m high which intrudes the Devonian Keevy Peak Formation basement and overlying Tertiary Suntrana Formation.\" Ar/Ar dating by Athey and others (2006) yields an age for Jumbo Dome of 1.026 +/- 0.057 Ma.","NameOrigin":"\"Jumbo Dome\" is a local name reported in 1906 by L.M. Prindle (Orth, 1971)."},{"VolcanoId":"ak325","Vnum":null,"Volcano":"Wilcox","OfficialName":null,"ParentVolcanoId":"ak246","ParentVolcano":"Seguam","AgeClass":"SuspHolo","AgeSource":"Jicha and Singer (2006) dated rocks from Wilcox volcano from 98-12 ka, and show that it also experienced a sector collapse and lateral blast at 9 ka.","Composition":"unknown","IsMonitored":false,"VolcanoType":"Cone","NvewsThreat":null,"Description":"From Jicha and Singer, 2006: Wilcox is composed of \"tens of basaltic to rhyolitic flows (wvl) of variable thickness that dip 30-40 degrees radially away from the former central vent now occupied by a 0.6 cubic km rhyolitic cone. Several of the andesitic to rhyolitic lavas making up the northern flank (rdf, awf, afp, rfc) spread out laterally as they approached the shoreline. It is unclear how far the lavas extended to the south because intense wave action has eroded away much of the southern flank of the volcano.///The lowest exposures of the stratocone consist of basalt flows intercalated wtih thick pyroclastic breccias and subvertical dikes. Several of the flows in this section are moderately oxidized, contain chlorite and serpentinized olivine, and are weakly hydrothermally altered. Nonetheless, 40Ar/39Ar ages of 98 +/- 18, 85 +/- 14, and 66 +/- 14 ka were obtained from stratigraphically successive basaltic lavas. These basal units are capped by numerous basaltic andesitic to rhyolitic flows that erupted from 62 to 27 ka. At 23 +/- 5 ka, the eruption of a \u003eor= 0.02 cubic km andesitic (62 wt.% SiO2) ignimbrite filled a valley between Finch Cove rhyolite (rfc) and Finch Cove rhyodacite (rdf). The ~25 m thick ignimbrite is moderately welded throughout and contains ~20% phenocrysts (12% plagioclase; 4% clinopyroxene, 2% olivine; 2% oxides), abundant lithics (up to 20 cm), and pumice (15-40 cm). Some of the last activity at Wilcox volcano prior to the sector collapse at ca. 9 ka included the eruption of dacitic to rhyolitic lavas, which formed Moundhill Point and the adjacent region to the south.\"","NameOrigin":"\"Wilcox volcano\" is an informal name."},{"VolcanoId":"ak195","Vnum":null,"Volcano":"Moundhill","OfficialName":"Moundhill Point","ParentVolcanoId":"ak246","ParentVolcano":"Seguam","AgeClass":"SuspHolo","AgeSource":"Jicha and Singer (2006) state that Moundhill is a late Holocene postglacial cone, but were unsuccessful in attempts to date its lavas by 40Ar/39Ar.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Monogenetic Cone","NvewsThreat":null,"Description":"From Jicha and Singer, 2006: Moundhill is a postglacial monogenetic cone. \"Its southeastern flank is built upon 15-20 m of andesitic lavas of unknown age, but the remainder of the cone rises from sea level up to 590 m. The entire cone is composed of numerous 1-3-m-thick, sheet-like, chemically monotonous basalt flows (mvl) distinguished by unusuallylarge (up to 0.7 cm) and abundant plagioclase (40 modal %), clinopyroxene (9%), and olivine (6%) phenocrysts in a glassy matrix. Each flow exhibits pahoehoe structure and extends from near the summit crater all the way to the coast. Levees on several flows descending from the west side of the crater suggest that the inital flow direction was westward, but then shifted to the north or south around the flanks of the stratovolcano. It is possible that the entire cone formed during a single, long-lasting eruption. Several attempts to obtain 40Ar/39Ar ages from Moundhill volcano lavas were unsuccessful due to very low radiogeneic 40AR* yields.","NameOrigin":"The cone at Moundhill Point is informally called \"Moundhill.\"  Moundhill Point was named by Lieutenant Commander H.E. Nichols, U.S. Navy, in 1883 (Orth, 1971)."},{"VolcanoId":"ak180","Vnum":null,"Volcano":"Lava Point","OfficialName":"Lava Point","ParentVolcanoId":"ak6","ParentVolcano":"Akutan","AgeClass":"SuspHolo","AgeSource":"Richter and others (1998) map this vent as Holocene.","Composition":"andesite","IsMonitored":false,"VolcanoType":null,"NvewsThreat":null,"Description":null,"NameOrigin":"\"Lava Point\" is a descriptive name gien by a special U.S. Navy survey party because the point forms the terminus of an extensive lava flow. The name was published by the U.S. Coast and Geodetic Survey in the 1944 Aleutian Coast Pilot (Orth, 1971)."},{"VolcanoId":"ak115","Vnum":null,"Volcano":"Half Peak","OfficialName":null,"ParentVolcanoId":"ak6","ParentVolcano":"Akutan","AgeClass":null,"AgeSource":null,"Composition":null,"IsMonitored":false,"VolcanoType":null,"NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak101","Vnum":null,"Volcano":"Flat Top Peak","OfficialName":"Flat Top Peak","ParentVolcanoId":"ak6","ParentVolcano":"Akutan","AgeClass":"Pleistocene","AgeSource":"Richter and others (1998) give a 40Ar/39Ar age date of 0.25 Ma, with some rocks in the sequence being younger.","Composition":"unknown","IsMonitored":false,"VolcanoType":null,"NvewsThreat":null,"Description":null,"NameOrigin":"Flat Top Peak was named by J.J. Gilbert of the U.S. Coast and Geodetic Survey, commander of the steamer Pathfinder during 1900-01 (Orth, 1971)."},{"VolcanoId":"ak41","Vnum":null,"Volcano":"Cascade Bight","OfficialName":null,"ParentVolcanoId":"ak6","ParentVolcano":"Akutan","AgeClass":"Pleistocene","AgeSource":"Richter and others (1998) give a 40Ar/39Ar age date of 0.15 Ma, with some rocks in the sequence being younger.","Composition":"unknown","IsMonitored":false,"VolcanoType":null,"NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak183","Vnum":null,"Volcano":"Long Valley Center","OfficialName":null,"ParentVolcanoId":"ak6","ParentVolcano":"Akutan","AgeClass":"Pleistocene","AgeSource":"Richter and others (1998) give a 40Ar/39Ar age date of 0.58 Ma, with some rocks in the sequence being younger.","Composition":"unknown","IsMonitored":false,"VolcanoType":null,"NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak158","Vnum":null,"Volcano":"Kimikthak Hills","OfficialName":"Kimikthak Hills","ParentVolcanoId":"ak204","ParentVolcano":"Nunivak Island","AgeClass":"Pleistocene","AgeSource":"Hoare and others (1968) show Kimikthak Hill as between 0.9 and 0.3 Ma.","Composition":null,"IsMonitored":false,"VolcanoType":null,"NvewsThreat":null,"Description":null,"NameOrigin":"\"Kimikthak Hills\" is a Cup'ik name obtained by the U.S. Coast and Geodetic Survey in 1949 (Orth, 1971)."},{"VolcanoId":"ak320","Vnum":null,"Volcano":"West Trident","OfficialName":null,"ParentVolcanoId":"ak288","ParentVolcano":"Trident","AgeClass":"Pleistocene","AgeSource":"Hildreth and others (2003) give a K-Ar age of 44 +/- 12 ka for West Trident.","Composition":null,"IsMonitored":false,"VolcanoType":null,"NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak88","Vnum":null,"Volcano":"East Trident","OfficialName":null,"ParentVolcanoId":"ak288","ParentVolcano":"Trident","AgeClass":"Pleistocene","AgeSource":"Hildreth and others (2003) give K-Ar ages of 142 +/- 15 ka and 143 +/-8 ka for East Trident.","Composition":null,"IsMonitored":false,"VolcanoType":null,"NvewsThreat":null,"Description":"From Hildreth and Fierstien, 2003: \"Oldest of the Trident group, a small andesitic-dacite cone (58-65 percent SiO2) almost contiguous with Mount Katmai. The rugged edifice is exposed over a 4-by-3-km area, but its lower flanks are concealed beneath glaciers. The hydrothermally altered core of East Trident is gutted by five glacial cirques, exposing on steep glacial headwalls windwos of stratified ejecta in the interior of the skeletal cone. The aretes between cirques reveal structurally simple stacks of 10-25 radially dipping lava flows and breccia sheets. Most are silicic andesites 10-30 m thick, but 100-m-thick lava flows that support the southwest ridge and cap the northeast ridge are dacites (63-65 percent SiO2). The latter dacite, which extends nearly to the summit, yields a K-Ar age of 142 +/- 15 ka, indicating that most of East Trident is older still. An age of 143+/-8 ka for a near-basal andesite lava flow on the northwest arete suggests, however, that activity at the small East Trident cone was short lived. Peak 5700+, central prong of the \"trident\" as viewed from the southeast (the aspect that inspired the volcano's name; Griggs, 1922, p. 98-9), is not a separate cone but simply the ruggedly eroded southwest flank of East Trident. Reconstruction suggests that the cone may once have exceeded 6,600 ft in elevation, which would probably have made it the highest of the Trident summits.\"","NameOrigin":null},{"VolcanoId":"ak278","Vnum":311241,"Volcano":"Tanax̂ Angunax̂","OfficialName":null,"ParentVolcanoId":"ak278","ParentVolcano":"Tanax̂ Angunax̂","AgeClass":"SuspHolo","AgeSource":"On the basis of fresh morphology, Nye and the Global Volcanism Program believe Tana has Holocene eruptions. Fieldwork at Tana and Herbert (C. Neal and K. Nicolaysen,\r\npersonal commun., 2016) revealed the presence of high-temperature fumaroles.","Composition":"unknown","IsMonitored":false,"VolcanoType":"Location given for the higher of two stratocones on eastern Chuginadak Island","NvewsThreat":"Low Threat","Description":"The volcano on the eastern end of Chuginadak Island has been informally called \"Tana\" in older publications, but is more properly referenced as Tanax̂ Angunax̂. From Smithsonian Institution, online Global Volcanism Program database, accessed November 16, 2007: \"The Tana volcanic complex forming the eastern half of the dumbbell-shaped Chuginadak Island, opposite the dramatic conical Cleveland stratovolcano, is composed of two prominent E-W-trending volcanoes. The complex shows evidence of glacial erosion, but the observation on satellite imagery of highly irregular coastlines forming peninsulas west of Applegate Cove on the NW side of the complex and Concord Point on the south side imply lava flows of mid- to late-Holocene age (Nye 2007, pers. comm.). Prominent lava flow levees are visible near Concord Point, where a low-silica rhyolite sample was obtained. The undissected cone and youthful crater forming the western summit also imply a post-glacial age, and youthful cinder cones also lie east of the isthmus between Cleveland and Tana volcanoes.\" See http://www.avo.alaska.edu/volcanoes/volcinfo.php?volcname=Cleveland for Cleveland information.","NameOrigin":"Tanax̂ Angunax̂ is given as the feature name for the eastern part of Chuginadak Island (Bergsland, 1994). This feature does not yet (December 2023) have a formal placename listed by the U.S. Board of Geographic Names, and has previously informally been called \"Tana.\""},{"VolcanoId":"ak316","Vnum":null,"Volcano":"West Crater","OfficialName":null,"ParentVolcanoId":"ak326","ParentVolcano":"Wrangell","AgeClass":"SuspPleist","AgeSource":"Shown as Q on Richter and others, 2006 (SIM 2877)","Composition":"unknown","IsMonitored":false,"VolcanoType":null,"NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak149","Vnum":null,"Volcano":"Kettle Cape","OfficialName":null,"ParentVolcanoId":"ak206","ParentVolcano":"Okmok","AgeClass":"Holocene","AgeSource":"Beget amd others, 2004 (RI 2004-3)","Composition":null,"IsMonitored":false,"VolcanoType":null,"NvewsThreat":null,"Description":null,"NameOrigin":"\"Kettle Cape\" is an informal name for these volcanic vents, derived from the name of the nearby Kettle Cape itself. Kettle Cape is a translation of the Russian name \"M[ys] Kotel'noy,\" given by Tebenkov in 1852. The Aleut name is \"Utmak\" and may possibly be from the word \"utman,\" meaning \"in the midst of,\" according to R.H. Geoghegan (Orth, 1971)."},{"VolcanoId":"ak312","Vnum":null,"Volcano":"Waist Tuya 1","OfficialName":null,"ParentVolcanoId":"ak206","ParentVolcano":"Okmok","AgeClass":null,"AgeSource":null,"Composition":null,"IsMonitored":false,"VolcanoType":null,"NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak16","Vnum":null,"Volcano":"Aslik","OfficialName":null,"ParentVolcanoId":"ak206","ParentVolcano":"Okmok","AgeClass":null,"AgeSource":null,"Composition":null,"IsMonitored":false,"VolcanoType":null,"NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak152","Vnum":null,"Volcano":"Kidney Bean","OfficialName":null,"ParentVolcanoId":"ak206","ParentVolcano":"Okmok","AgeClass":null,"AgeSource":null,"Composition":null,"IsMonitored":false,"VolcanoType":null,"NvewsThreat":null,"Description":null,"NameOrigin":"\"Kidney Bean\" is an informal descriptive name."},{"VolcanoId":"ak121","Vnum":null,"Volcano":"Idak cindercones","OfficialName":null,"ParentVolcanoId":"ak206","ParentVolcano":"Okmok","AgeClass":null,"AgeSource":null,"Composition":null,"IsMonitored":false,"VolcanoType":null,"NvewsThreat":null,"Description":null,"NameOrigin":"\"Idak cindercones\" are informally named after Cape Idak. Cape Idak's name was published by Captain Tebenkov in 1852, as \"M[ys] Idakh\" or \"Cape Idak.\" R.H. Geoghegan believes the name to be the Aleut name \"Idakug\" meaning \"exit or outlet\" (Orth, 1971)."},{"VolcanoId":"ak87","Vnum":null,"Volcano":"East Tanaga","OfficialName":null,"ParentVolcanoId":"ak280","ParentVolcano":"Tanaga","AgeClass":"SuspHolo","AgeSource":"Coombs and others (2007) state that East Tanaga is Holocene in age.","Composition":"unknown","IsMonitored":false,"VolcanoType":null,"NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak193","Vnum":null,"Volcano":"Moffett parasitic cone","OfficialName":null,"ParentVolcanoId":"ak192","ParentVolcano":"Moffett","AgeClass":null,"AgeSource":null,"Composition":null,"IsMonitored":false,"VolcanoType":null,"NvewsThreat":null,"Description":null,"NameOrigin":"\"Moffitt parasitic cone\" is an informal name."},{"VolcanoId":"ak173","Vnum":null,"Volcano":"Kshaliuk Point","OfficialName":null,"ParentVolcanoId":"ak229","ParentVolcano":"Recheshnoi","AgeClass":null,"AgeSource":null,"Composition":null,"IsMonitored":false,"VolcanoType":null,"NvewsThreat":null,"Description":null,"NameOrigin":"\"Kshaliuk Point\" is an informal name as applied to the volcanic features near Kshaliuk Point itself."},{"VolcanoId":"ak321","Vnum":null,"Volcano":"West Vent","OfficialName":null,"ParentVolcanoId":"ak229","ParentVolcano":"Recheshnoi","AgeClass":"Holocene","AgeSource":"Recheshnoi's west vent has a 3000 year old lava flow (Nye's data).","Composition":null,"IsMonitored":false,"VolcanoType":"Source of 3000 yr old flow to beach","NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak239","Vnum":null,"Volcano":"Russian Bay domes","OfficialName":null,"ParentVolcanoId":"ak229","ParentVolcano":"Recheshnoi","AgeClass":null,"AgeSource":null,"Composition":"rhyolite","IsMonitored":false,"VolcanoType":"Rhyolite dome chain","NvewsThreat":null,"Description":null,"NameOrigin":"\"Russian Bay domes\" is an informal name, after nearby Russian Bay."},{"VolcanoId":"ak226","Vnum":null,"Volcano":"Qtz-Ol-And vent","OfficialName":null,"ParentVolcanoId":"ak229","ParentVolcano":"Recheshnoi","AgeClass":null,"AgeSource":null,"Composition":null,"IsMonitored":false,"VolcanoType":null,"NvewsThreat":null,"Description":null,"NameOrigin":"\"Otz-Ol-And vent\" is an informal name."},{"VolcanoId":"ak51","Vnum":null,"Volcano":"Cinder Point","OfficialName":null,"ParentVolcanoId":"ak206","ParentVolcano":"Okmok","AgeClass":null,"AgeSource":null,"Composition":null,"IsMonitored":false,"VolcanoType":null,"NvewsThreat":null,"Description":null,"NameOrigin":"Cinder Point was named in 1938 by the U.S. Coast and Geodetic Survey, as a descriptive name \"because of the prominent cinder cone on point\" (Orth, 1971)."},{"VolcanoId":"ak313","Vnum":null,"Volcano":"Waist Tuya 2","OfficialName":null,"ParentVolcanoId":"ak206","ParentVolcano":"Okmok","AgeClass":null,"AgeSource":null,"Composition":null,"IsMonitored":false,"VolcanoType":null,"NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak314","Vnum":null,"Volcano":"Waist Tuya 3","OfficialName":null,"ParentVolcanoId":"ak206","ParentVolcano":"Okmok","AgeClass":null,"AgeSource":null,"Composition":null,"IsMonitored":false,"VolcanoType":null,"NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak310","Vnum":null,"Volcano":"Waist cone/flow 1","OfficialName":null,"ParentVolcanoId":"ak206","ParentVolcano":"Okmok","AgeClass":null,"AgeSource":null,"Composition":null,"IsMonitored":false,"VolcanoType":null,"NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak311","Vnum":null,"Volcano":"Waist cone/flow 2","OfficialName":null,"ParentVolcanoId":"ak206","ParentVolcano":"Okmok","AgeClass":null,"AgeSource":null,"Composition":null,"IsMonitored":false,"VolcanoType":null,"NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak309","Vnum":null,"Volcano":"Waist cone 3","OfficialName":null,"ParentVolcanoId":"ak206","ParentVolcano":"Okmok","AgeClass":null,"AgeSource":null,"Composition":null,"IsMonitored":false,"VolcanoType":null,"NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak196","Vnum":null,"Volcano":"N caldera","OfficialName":null,"ParentVolcanoId":"ak105","ParentVolcano":"Frosty","AgeClass":"SuspPleist","AgeSource":"Quaternary - unable to find definitive grouping other than that.","Composition":"mafic","IsMonitored":false,"VolcanoType":null,"NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak240","Vnum":null,"Volcano":"S caldera","OfficialName":null,"ParentVolcanoId":"ak105","ParentVolcano":"Frosty","AgeClass":"SuspPleist","AgeSource":"Quaternary (Wilson and others, 1992)","Composition":"mafic","IsMonitored":false,"VolcanoType":null,"NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak287","Vnum":null,"Volcano":"Trader Mtn","OfficialName":null,"ParentVolcanoId":"ak287","ParentVolcano":"Trader Mtn","AgeClass":"Pleistocene","AgeSource":"Wilson and others (1995) report a K-Ar age of 0.98 +/- 0.05 Ma for Trader Mountain.","Composition":"dacite","IsMonitored":false,"VolcanoType":"Pleistocene stratocone","NvewsThreat":null,"Description":"Trader Mountain is a small dacitic stratocone-like feature with an extrusive dome; lava flows dip away from the center in all directions (Chris Nye, oral commun., 2007).  Wilson and others (1995) alternatively describe Trader Mountain as a hypabyssal dacite plug, and report a \"potassium-argon age of 0.98+/- 0.05 Ma (F.H. Wilson and Nora Shew, unpub. data, 1988).\"","NameOrigin":"\"Trader Mountain\" is a local name reproted by the U.S. Geological Survey in 1929. It may be named after the nearby Traders Cove (Orth, 1971)."},{"VolcanoId":"ak327","Vnum":null,"Volcano":"Wrangell Caldera","OfficialName":"Mount Wrangell Crater","ParentVolcanoId":"ak326","ParentVolcano":"Wrangell","AgeClass":"SuspPleist","AgeSource":"Shown as Q on Richter and others, 2006 (SIM 2877)","Composition":null,"IsMonitored":false,"VolcanoType":"Center point of Wrangell Caldera","NvewsThreat":null,"Description":null,"NameOrigin":"The name \"Mount Wrangell Crater\" was published by the U.S. Geological Survey in 1931 (Orth, 1971)."},{"VolcanoId":"ak163","Vnum":null,"Volcano":"Klawasi Group","OfficialName":null,"ParentVolcanoId":"ak163","ParentVolcano":"Klawasi Group","AgeClass":null,"AgeSource":null,"Composition":null,"IsMonitored":false,"VolcanoType":"Group of mud volcanoes","NvewsThreat":null,"Description":"   The Klawasi Group is composed of \"three large mud volcanoes located approximately 27 km (17 mi) east of Glennallen near the west slope of the the Pleistocene volcano, Mt. Drum, in the Copper River Basin of southcentral Alaska.\" (McGimsey and Wallace, 1999).  The three mud volcanoes are named Upper Klawasi, Lower Klawasi, and Shrub.  \"Shrub rises 340 ft (~100 m) above surrounding terrain and is composed of deposits derived from underlying glaciolacustrine sediments of the Basin (Richter and others, 1998).  Low-level mud and minor gas emission has historically been almost constant at the other two mud volcanoes; Shrub [was] virtually inactive for decades with only some minor discharge observed in the mid-1950's (Nichols and Yehle, 1961).  During the spring of 1997, Shrub began to vigorously erupt CO2-rich gas and warm saline mud\" (McGimsey and Wallace, 1999).\r\n   Motyka and others (1989) show how helium and carbon isotope ratios provide good evidence that the Klawasi CO2 is derived from a magmatic intrusive with additional contributions of CO2 from contact metamorphism of deep-seated limestone beds.","NameOrigin":"\"Klawasi Group\" is an informal name applied to the group of mud volcanoes to the west of Mount Drum. Their name is derived from the nearby Klawasi River."},{"VolcanoId":"ak27","Vnum":null,"Volcano":"Blue Mtn","OfficialName":"Blue Mountain","ParentVolcanoId":"ak27","ParentVolcano":"Blue Mtn","AgeClass":"Pleistocene","AgeSource":"Hildreth and others (2007): A single 40Ar/39Ar age was determined for Blue Mountain, on a groundmass concentrate of dacite sample U-19 from the south-trending ridge of summit Dome 1776.  Its weighted-mean plateau age is 632+/-7 ka","Composition":null,"IsMonitored":false,"VolcanoType":"Dome cluster","NvewsThreat":null,"Description":"   From Hildreth and others (2007): \"Blue Mountain consists of 13 dacite domes in a cluster ~6 km long, similar in extent and configuration to what the Kaguyak dome cluster, 200 km to the northeast, had been before its mid-Holocene caldera-forming eruption (Fierstein and Hildreth, in press).  Three of the Blue Mountain domes form a separate group, ~1 km north of the main cluster, although they are chemically and mineralogically similar to the rest.  The two large central domes (Domes 1776, 1700) abut each other and together form the main ridge of the Blue Mountain edifice.  From each dome issued stubby 200-m-thick flow lobes that form three southerly trending ridges.  Eight satellite domes are contiguous with the central ridge, four at its northwest end and four at its southeast end.  The smallest domes have as little as 100m of relief, and the four largest stand \u003e300 m above the surrounding apron of glacial and colluvial deposits.\"\r\n   \"A single 40Ar/39Ar age was determined for Blue Mountain, on a groundmass concentrate of dacite sample U-19 from the south-trending ridge of summit Dome 1776.  Its weighted-mean plateau age is 632+/-7 ka, categorically middle Pleistocene and about 25 times older than the lithologically and compositionally similar domes at The Gas Rocks.  At Blue Mountain, the several satellitic domes surrounding dated Dome 1776 are unlikely to differ much in age, although the noncontiguous northern group might conceivably do so.  We discerned no significant differences in degree of erosion, and the chemical and petrographic similarities of nearly all the domes in both groups suggest no basis for inferring an exceptionally protracted eruptive sequence.\"","NameOrigin":"\"Blue Mountain\" was reported as a local name by the U.S. Geological Survey in 1952 (Orth, 1971)."},{"VolcanoId":"ak336","Vnum":null,"Volcano":"North Walrus Peak","OfficialName":null,"ParentVolcanoId":"ak194","ParentVolcano":"Morzhovoi","AgeClass":"SuspPleist","AgeSource":"Brophy, in Wood and Kienle (1990), states that the Morzhovoi volcanics are late Pliocene to early Pleistocene.","Composition":null,"IsMonitored":false,"VolcanoType":null,"NvewsThreat":null,"Description":null,"NameOrigin":"\"North Walrus Peak\" was named \"Morzhevskoy pik\" meaning \"walrus peak\" by Captain Lutke in 1836 (Orth, 1971)."},{"VolcanoId":"ak337","Vnum":null,"Volcano":"South Walrus Peak","OfficialName":null,"ParentVolcanoId":"ak194","ParentVolcano":"Morzhovoi","AgeClass":"SuspPleist","AgeSource":"Brophy, in Wood and Kienle (1990), states that the Morzhovoi volcanics are late Pliocene to early Pleistocene.","Composition":null,"IsMonitored":false,"VolcanoType":null,"NvewsThreat":null,"Description":null,"NameOrigin":"\"South Walrus Peak\" is a descriptive name published by the U.S. Coast and Geodetic Survey in the 1947 Coast Pilot (Orth, 1971)."},{"VolcanoId":"ak338","Vnum":null,"Volcano":"Mafic Knob 500","OfficialName":null,"ParentVolcanoId":"ak295","ParentVolcano":"Ugashik-Peulik","AgeClass":"SuspHolo","AgeSource":"Miller (2004) assumes a Holocene age for Mafic Knob 500.","Composition":"basaltic_andesite","IsMonitored":false,"VolcanoType":"Post-glacial mafic lava mesa; possible flank vent for Peulik (Hildreth and others, 2007),","NvewsThreat":null,"Description":"   From Hildreth and others (2007): \"About 5 km east of Ukinrek Maars, a circular mesa of postglacial mafic lava (53.6-54.1 weight percent SiO2), ~1 km in diameter, stands 100 m above a surrounding hummocky lowland that consists of lake deposits and a debris-avalanche sheet derived from the Ugashik-Peulik edifice. The rugged surface of the mesa, corrugated by several pressure ridges, has not been overridden by either ice or avalanche, and the lava appears to have welled up in place and spread out locally, as if confined. The unit is compositionally similar to the postglacial lava flows that make up the cone and apron of Mount Peulik (Miller, 2004), but is distinguishable from all other units in the district. This enigmatic exposure may represent an authentic flank vent for Peulik magma, or, conceivably, a rootless secondary vent for invasive lava that had burrowed beneath the avalanche deposit.\"","NameOrigin":null},{"VolcanoId":"ak339","Vnum":null,"Volcano":"Lone basalt","OfficialName":"Lone Hill","ParentVolcanoId":"ak339","ParentVolcano":"Lone basalt","AgeClass":"Pleistocene","AgeSource":"Wilson and Shew (1992) determined a whole-rock K-Ar age of 593+/-73 ka for the Lone basalt.","Composition":"basalt","IsMonitored":false,"VolcanoType":"Glacially scoured ridge of olivine-basaltic lava","NvewsThreat":null,"Description":"From Hildreth and others (2007): \"About 10 km southwest of Blue Mountain, an isolated 0.38-km-square-area exposure of olivine-basaltic lava (50 weight percent SiO2, 7 weight percent MgO) forms a subdued, glacially scoured ridge (Lone basalt) that rises 80 m above the surrounding muskeg. The rock contains 5 to 8 volume percent olivine phenocrysts (0.5-2 mm diam) and sparse oxide microphenocrysts in a holocrystalline groundmass of intergrown plagioclase laths and equant grains of olivine, oxides, and rare clinopyroxene. This subalkaline basalt is similar to, but not quite as primitive as, the basalt of Ukinrek Maars. It differs compositionally, however, from the mafic rocks of nearby Mount Peulik (Miller, 2004) and from those of the other arc-front centers nearby, and is not demonstrably related to Blue Mountain dacite. Nonetheless, the composition of the Lone basalt is not far from that of the mafic enclaves in Blue Mountain dacite, nor from that of the 500-ka subalkaline basaltic cone at Gertrude Creek northeast of Becharof Lake. Wilson and Shew (1992) determined a whole-rock K-Ar age of 593+/-73 ka for the Lone basalt.","NameOrigin":"Lone Hill was named by the U.S. Geological Survey in 1956 (Orth, 1971)."},{"VolcanoId":"ak341","Vnum":null,"Volcano":"Arena Cove","OfficialName":"Arena Cove","ParentVolcanoId":"ak284","ParentVolcano":"Tlevak Strait volcanic field","AgeClass":"SuspHolo","AgeSource":"Although Eberlein and others (1983) suspect Quaternary or Holocene age for the Tlevak Strait-Suemez Island volcanics, Brew and others (1996) map them as Quaternary-Tertiary.","Composition":null,"IsMonitored":false,"VolcanoType":null,"NvewsThreat":null,"Description":null,"NameOrigin":"Arena Cove was named in 1923 by the U.S. Coast and Geodetic Survey, because \"arena\" means \"sand\" in Spanish. Arena Cove is fringed by beaches of sand, and shaped like a curving arena (Orth, 1971)."},{"VolcanoId":"ak340","Vnum":null,"Volcano":"Unimak 5270","OfficialName":null,"ParentVolcanoId":"ak340","ParentVolcano":"Unimak 5270","AgeClass":"Pleistocene","AgeSource":"Nye (written commun., 2008) believes Unimak 5270 is Pleistocene in age.","Composition":"unknown","IsMonitored":false,"VolcanoType":null,"NvewsThreat":null,"Description":"Unimak 5270 is an unnamed Pleistocene volcanic center between Isanotski and Roundtop on Unimak Island. Observations made from a helicopter during multiple flybys (during Shishaldin fieldwork) show that lava flows dip radially away from the summit, thus Unimak 5270 was a separate vent/volcano (from Chris Nye, 2008, written commun.)","NameOrigin":"\"Unimak 5270\" is an informal name, given because the highest peak of this volcanic center is 5270 feet in elevation."},{"VolcanoId":"ak342","Vnum":null,"Volcano":"Monogenetic QT vents of WWVF","OfficialName":null,"ParentVolcanoId":"ak342","ParentVolcano":"Monogenetic QT vents of WWVF","AgeClass":"SuspPleist","AgeSource":"Amy Lunt MS thesis (1997), citation 6122.","Composition":"","IsMonitored":false,"VolcanoType":"Cinder cones and eruptive centers","NvewsThreat":null,"Description":"The Monogenetic QT vents of the WWVF (Western Wrangell Volcanic Field) were named the \"interior mesas\" by Preece (1997) and Lunt (1997). Lunt describes the vents as a linear array of cinder cones and small eruptive centers within the western Wrangell volcanic field. The region is topographically subdued between the front and back side volcanic chains of the Wrangell Volcanic Field. Volcanic features include (but are not limited to), West Cone, East Cone, Cone Ridge, and Jaeger Mesa. Vents appear to be  Pleistocene to late Tertiary in age.","NameOrigin":"\"Monogenetic QT vents of the WWVF\" is an informal name given by Chris Nye (2011). Preece (1997) and Lunt (1997) refer to this grouping of vents as \"Interior Mesas\""},{"VolcanoId":"","Vnum":null,"Volcano":"West Cone","OfficialName":null,"ParentVolcanoId":"ak342","ParentVolcano":"Monogenetic QT vents of WWVF","AgeClass":null,"AgeSource":null,"Composition":null,"IsMonitored":false,"VolcanoType":null,"NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"","Vnum":null,"Volcano":"East Cone","OfficialName":null,"ParentVolcanoId":"ak342","ParentVolcano":"Monogenetic QT vents of WWVF","AgeClass":null,"AgeSource":null,"Composition":null,"IsMonitored":false,"VolcanoType":null,"NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"","Vnum":null,"Volcano":"Jaeger Mesa","OfficialName":null,"ParentVolcanoId":"ak342","ParentVolcano":"Monogenetic QT vents of WWVF","AgeClass":null,"AgeSource":null,"Composition":null,"IsMonitored":false,"VolcanoType":null,"NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"","Vnum":null,"Volcano":"Horseshoe Mesa","OfficialName":null,"ParentVolcanoId":"ak109","ParentVolcano":"Gordon","AgeClass":null,"AgeSource":null,"Composition":null,"IsMonitored":false,"VolcanoType":null,"NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak347","Vnum":null,"Volcano":"Ahmanilix","OfficialName":null,"ParentVolcanoId":"ak206","ParentVolcano":"Okmok","AgeClass":"Historical","AgeSource":"Larsen and others (2015)","Composition":null,"IsMonitored":false,"VolcanoType":"tephra cone","NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak348","Vnum":null,"Volcano":"Ingenstrem Depression Volcanic Field","OfficialName":null,"ParentVolcanoId":"ak348","ParentVolcano":"Ingenstrem Depression Volcanic Field","AgeClass":"SuspHolo","AgeSource":"Yogodzinski and others, 2015","Composition":"basalt","IsMonitored":false,"VolcanoType":"submarine volcanic field","NvewsThreat":null,"Description":"From Yogodzinski and others (2015): The \"Ingenstrem   Depression - a fault-bounded rectangular basin, approximately 60 km long by  10-15 km  wide and 2000 m  deep, which sits along the crest of the Aleutian ridge, between Attu and Buldir islands. Seafloor mapping reveals the presence of many small volcanic cones and associated  lava flows, in and around  the  margins of the  Ingenstrem Depression. The largest cones have base diameters of 2-4 km and are 300-600 m in height. Most appear to be undeformed, constructional volcanic features. Spatial analysis of bathymetric data indicates that there are 134 volcanic cones in the Ingenstrem Depression, which constitute a combined volume of 10 cubic kilometers - a volume similar to that of single, small,  emergent calc-alkaline volcanoes found throughout the arc (White and others, 2007).\"","NameOrigin":"Ingenstrem Depression Volcanic Field is an informal name given to these volcanic vents by Yogodzinski and others, 2015."},{"VolcanoId":"","Vnum":null,"Volcano":"Back West","OfficialName":null,"ParentVolcanoId":"ak348","ParentVolcano":"Ingenstrem Depression Volcanic Field","AgeClass":"","AgeSource":"This submarine cone is located and listed based on sonar bathymetric data and dredge results of the 2005 Western Aleutian Volcano Expedition bathymetric survey and dredge program, RV Thompson, Gene Yogodzinski chief scientist. The youngest age of this ven","Composition":null,"IsMonitored":false,"VolcanoType":"Submarine","NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"","Vnum":null,"Volcano":"Madonna","OfficialName":null,"ParentVolcanoId":"ak348","ParentVolcano":"Ingenstrem Depression Volcanic Field","AgeClass":"","AgeSource":"This submarine cone is located and listed based on sonar bathymetric data and dredge results of the 2005 Western Aleutian Volcano Expedition bathymetric survey and dredge program, RV Thompson, Gene Yogodzinski chief scientist. The youngest age of this ven","Composition":null,"IsMonitored":false,"VolcanoType":"Submarine","NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"","Vnum":null,"Volcano":"Down South","OfficialName":null,"ParentVolcanoId":"ak348","ParentVolcano":"Ingenstrem Depression Volcanic Field","AgeClass":"","AgeSource":"This submarine cone is located and listed based on sonar bathymetric data and dredge results of the 2005 Western Aleutian Volcano Expedition bathymetric survey and dredge program, RV Thompson, Gene Yogodzinski chief scientist. The youngest age of this ven","Composition":null,"IsMonitored":false,"VolcanoType":"Submarine","NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"","Vnum":null,"Volcano":"Snake River Plains","OfficialName":null,"ParentVolcanoId":"ak348","ParentVolcano":"Ingenstrem Depression Volcanic Field","AgeClass":"","AgeSource":"This submarine cone is located and listed based on sonar bathymetric data and dredge results of the 2005 Western Aleutian Volcano Expedition bathymetric survey and dredge program, RV Thompson, Gene Yogodzinski chief scientist. The youngest age of this ven","Composition":null,"IsMonitored":false,"VolcanoType":"Submarine","NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"","Vnum":null,"Volcano":"Dwight East","OfficialName":null,"ParentVolcanoId":"ak348","ParentVolcano":"Ingenstrem Depression Volcanic Field","AgeClass":null,"AgeSource":"This submarine cone is located and listed based on sonar bathymetric data and dredge results of the 2005 Western Aleutian Volcano Expedition bathymetric survey and dredge program, RV Thompson, Gene Yogodzinski chief scientist. The youngest age of this ven","Composition":null,"IsMonitored":false,"VolcanoType":"Submarine","NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"","Vnum":null,"Volcano":"Willy","OfficialName":null,"ParentVolcanoId":"ak348","ParentVolcano":"Ingenstrem Depression Volcanic Field","AgeClass":"","AgeSource":"This submarine cone is located and listed based on sonar bathymetric data and dredge results of the 2005 Western Aleutian Volcano Expedition bathymetric survey and dredge program, RV Thompson, Gene Yogodzinski chief scientist. The youngest age of this ven","Composition":null,"IsMonitored":false,"VolcanoType":"Submarine","NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"","Vnum":null,"Volcano":"Up South","OfficialName":null,"ParentVolcanoId":"ak348","ParentVolcano":"Ingenstrem Depression Volcanic Field","AgeClass":null,"AgeSource":"This submarine cone is located and listed based on sonar bathymetric data and dredge results of the 2005 Western Aleutian Volcano Expedition bathymetric survey and dredge program, RV Thompson, Gene Yogodzinski chief scientist. The youngest age of this ven","Composition":null,"IsMonitored":false,"VolcanoType":"Submarine","NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"","Vnum":null,"Volcano":"70B29","OfficialName":null,"ParentVolcanoId":"ak348","ParentVolcano":"Ingenstrem Depression Volcanic Field","AgeClass":null,"AgeSource":"Yogodzinski and others, 2015","Composition":null,"IsMonitored":false,"VolcanoType":"Submarine","NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"","Vnum":null,"Volcano":"Crinkly","OfficialName":null,"ParentVolcanoId":"ak348","ParentVolcano":"Ingenstrem Depression Volcanic Field","AgeClass":null,"AgeSource":"Yogodzinski and others, 2015","Composition":null,"IsMonitored":false,"VolcanoType":"Submarine","NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"","Vnum":null,"Volcano":"Muffin","OfficialName":null,"ParentVolcanoId":"ak348","ParentVolcano":"Ingenstrem Depression Volcanic Field","AgeClass":null,"AgeSource":"Yogodzinski and others, 2015","Composition":null,"IsMonitored":false,"VolcanoType":"Submarine","NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"","Vnum":null,"Volcano":"Parasite 1","OfficialName":null,"ParentVolcanoId":"ak348","ParentVolcano":"Ingenstrem Depression Volcanic Field","AgeClass":null,"AgeSource":"Yogodzinski and others, 2015","Composition":null,"IsMonitored":false,"VolcanoType":"Submarine","NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"","Vnum":null,"Volcano":"Parasite 2","OfficialName":null,"ParentVolcanoId":"ak348","ParentVolcano":"Ingenstrem Depression Volcanic Field","AgeClass":null,"AgeSource":"Yogodzinski and others, 2015","Composition":null,"IsMonitored":false,"VolcanoType":"Submarine","NvewsThreat":null,"Description":null,"NameOrigin":null},{"VolcanoId":"ak349","Vnum":null,"Volcano":"Western Cones","OfficialName":null,"ParentVolcanoId":"ak349","ParentVolcano":"Western Cones","AgeClass":"SuspHolo","AgeSource":"Yogodzinski and others, 2015","Composition":null,"IsMonitored":false,"VolcanoType":"submarine volcanic field","NvewsThreat":null,"Description":"Yogodzinski and others (2015) dredged western Aleutian submarine volcanic cones at \"an unnamed location 300 km west of Buldir Island, which we refer to as the Western Cones area. This area includes five small cones, aligned along a volcanic front for a distance of about 70 km. The largest of the cones, which has a base diameter of 5-10 km and is 600 m high, is similar in size to emergent volcanoes in the western Aleutians, such as Buldir, Kiska, and Little Sitkin.\"","NameOrigin":"Western Cones is an informal name given to these volcanic vents by Yogodzinski and others, 2015."},{"VolcanoId":"ak350","Vnum":315100,"Volcano":"Maclaren River volcanic field","OfficialName":null,"ParentVolcanoId":"ak350","ParentVolcano":"Maclaren River volcanic field","AgeClass":"Pleistocene","AgeSource":"Bearden, 2023","Composition":null,"IsMonitored":false,"VolcanoType":"Volcanic field","NvewsThreat":null,"Description":"The Pleistocene Maclaren River volcanic field was first recognized by Brueske et al. 2023 and has been further characterized by Bearden 2023. The field, located east of the Maclaren River on either side of the Denali Highway, includes at least three monogenetic volcanoes that date from the last million years. The three identified features lie along a ~20 mile, NNE-SSW line that approximately traces the position of a tear in the Yakutat plate currently subducting under southcentral Alaska@15788@. The field occurs in an area informally called “the Denali gap,” between the Aleutian and Wrangell arc volcanoes, where only minor volcanism has been identified (see also Buzzard Creek and Jumbo Dome). The lavas from the three volcanoes of the Maclaren River volcanic field are basaltic to basaltic andesitic in composition @15848@.","NameOrigin":"The \"Maclaren River volcanic field\" is an informal name, named after nearby Maclaren River, by Bearden, 2023."},{"VolcanoId":"ak351","Vnum":null,"Volcano":"Maclaren River volcanic field Volcano #1","OfficialName":null,"ParentVolcanoId":"ak350","ParentVolcano":"Maclaren River volcanic field","AgeClass":"Pleistocene","AgeSource":"Bearden, 2023","Composition":null,"IsMonitored":false,"VolcanoType":"Volcano remnant","NvewsThreat":null,"Description":"Volcano #1 of the Maclaren River volcanic field is its northmost identified feature @15788@, located approximately 11 miles north of the Denali Highway and 7.9 miles  northeast of volcano #2. It consists of olivine-phyric platy lavas @15848@. Due to the relatively inaccessible location of this volcano, a vent location has yet to be identified. The lavas are basaltic andesite in composition, and date to 958,000 years ago. The proposed origin of volcano #1 magma is lithospheric mantle with compositional influence from the subducting Yakutat plate @15848@.","NameOrigin":null},{"VolcanoId":"ak352","Vnum":null,"Volcano":"Maclaren River volcanic field Volcano #2","OfficialName":null,"ParentVolcanoId":"ak350","ParentVolcano":"Maclaren River volcanic field","AgeClass":"Pleistocene","AgeSource":"Bearden, 2023","Composition":null,"IsMonitored":false,"VolcanoType":"Lava flow field","NvewsThreat":null,"Description":"Volcano #2 of the Maclaren River volcanic field is approximately 3.2 miles north of the Denali Highway and consists of blocky to platy lavas and pyroclastic tephra @15848@. The vent, located at the northeastern edge of the deposits, is surrounded by platy lavas, while a blockier morphology is more common southward, closer to the Denali Highway. The pyroclastic tephra is concentrated near the vent. The vent location was identified from pyroclastic tephra, like blocks and bombs, that could not travel far from the vent due to weight. The estimated erupted area is 0.4 square miles, and the volume is 0.023 cubic miles. The composition of volcano #2 lavas is trachybasalt. Based on study of the geochemical characteristics of the lava, the magma source for volcano #2 is inferred to be metasomatized subcontinental lithospheric mantle (@15848).","NameOrigin":null},{"VolcanoId":"ak353","Vnum":null,"Volcano":"Maclaren River volcanic field Volcano #3","OfficialName":null,"ParentVolcanoId":"ak350","ParentVolcano":"Maclaren River volcanic field","AgeClass":"Pleistocene","AgeSource":"Bearden, 2023","Composition":null,"IsMonitored":false,"VolcanoType":"Lava flow field","NvewsThreat":null,"Description":"Volcano #3 of the Maclaren River volcanic field is located approximately 2.3 miles south of the Denali Highway and 5.6 miles south of Volcano #2@15848@. There are platy and blocky lavas as well as welded spatter at the vent location. The lavas appear to be benched on the eastern slide. The estimated erupted area is 0.2 square miles, and the volume is 0.007 cubic miles. The composition of the lava is basaltic andesite to andesite, and it dates to 422,000 years ago. Based on petrology, the magma source for volcano #3 is inferred to be subducting Yakutat slab@15848@.","NameOrigin":null},{"VolcanoId":"ak354","Vnum":315055,"Volcano":"Addington volcanic field","OfficialName":null,"ParentVolcanoId":"ak354","ParentVolcano":"Addington volcanic field","AgeClass":"SuspPleist","AgeSource":"Wilcox, 2017","Composition":null,"IsMonitored":false,"VolcanoType":"Volcanic field","NvewsThreat":null,"Description":"The Addington volcanic field consists of a submarine probable maar or crater with associated subtle volcanic cones @8043@ @13251@. This field lies offshore west of Cape Addington in Southeast Alaska. The crater is about 1 km wide and nearly circular in shape; the rim is about 243 feet (74 m) below sea level, and the crater floor is about 1195-951 feet (364-290 m) below sea level. Wilcox @13251@ and Wilcox and others @15944@ identify the Baker Island black tephra as potentially sourced from the Addington volcanic field, and date it to 13,492 +/- 237 cal yr BP.","NameOrigin":"The \"Addington volcanic field\" is an informal name, named after the nearby Cape Addington, by Greene, 2011."}]