Robert G. McGimsey

United States Geological Survey

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Christina A. Neal

Alaska Volcano Observatory

R. Wessels

United States Geological Survey

Michelle L. Coombs

Alaska Volcano Observatory

Michael P. Doukas

Cascades Volcano Observatory

William C. Evans

Marshall Space Flight Center

D. J. Schneider

United States Geological Survey

Christopher F. Waythomas

Alaska Volcano Observatory

K. F. Bull

Alaska Division of Geological and Geophysical Surveys

C. J. Nye

Alaska Division of Geological and Geophysical Surveys

Donald H. Richter

University of Alaska Fairbanks

Cooperative Institutions

United States Geological Survey

Alaska Volcano Observatory

University of Alaska Fairbanks

Cascades Volcano Observatory

Denver Federal Center

Volcano Science Center

Alaska Department of Natural Resources

United States Department of the Interior

Pacific Island Ecosystems Research Center

Alaska Division of Geological and Geophysical Surveys

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Volcanic activity in Alaska; summary of events and response of the Alaska Volcano Observatory, 1992

Antarctica A Keystone in a Changing World (1995)

Robert G. McGimsey Christina A. Neal Michael P. Doukas

10.3133/ofr9583

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Citations (18)

A postulated new source for the White River Ash, Alaska: A section in <i>Geologic studies in Alaska by the US. Geological Survey, 1990</i>

Robert G. McGimsey Donald H. Richter Gregory D. DuBois T. P. Miller

The White River Ash (Lerbekmo and others, 1968), product of two of the most voluminous pyroclastic eruptions in North America in the past 2,000 yr, blankets much of the Yukon Terrtory, Canada, and a small part of adjoining eastern Alaska. Lerbekmo and Campbell (1969) narrowed the source of the ash to an area northeast of the Mt. Bona-Mt. Churchill massif in the St. Elias Mountains of southern Alaska. Based on indirect evidence, Lerbekmo and Campbell (1969) further suggested that the vent was beneath the Klutlan Glacier, adjacent to a mound of coarse pumice, 16 km northeast of Mt. Bona. Recently discovered pumice and ash deposits and a possible vent structure near the summit of Mt. Churchill suggest an alternate source area. The White River Ash is a bilobate plinian fallout deposit covering more than 340,000 km2 and containing an estimated 25-50 km3 of tephra (Bostock, 1952; Berger, 1960; fig. 1). Radiocarbon ages indicate that the northern lobe was deposited about 1,887 yr B.P. and the eastern, and larger, lobe about 1,250 yr B.P. (Lerbekmo and others, 1975). The axes of the two lobes converge near Mt. Bona (16,420 ft (5,005 m)) and Mt. Churchill [15,638 ft (4,766 m)], which together form a prominent massif in the St. Elias Mountains. The Klutlan Glacier, a large valley glacier that flows eastward into Canada, has its principal source on the eastern flank of the massif.

Massif

Pumice

Volcanic ash

10.3133/70180193

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Citations (2)

Observations of Volcanic Clouds in Their First Few Days of Atmospheric Residence: The 1992 Eruptions of Crater Peak, Mount Spurr Volcano, Alaska

The Journal of Geology (2001)

William I. Rose G. J. Bluth D. J. Schneider Gérald Ernst Colleen Riley

Satellite SO2 and ash measurements of Mount Spurr's three 1992 volcanic clouds are compared with ground‐based observations to develop an understanding of the physical and chemical evolution of volcanic clouds. Each of the three eruptions with ratings of volcanic explosivity index three reached the lower stratosphere (14 km asl), but the clouds were mainly dispersed at the tropopause by moderate to strong (20–40 m/s) tropospheric winds. Three stages of cloud evolution were identified. First, heavy fallout of large (>500 μm) pyroclasts occurred close to the volcano (<25 km from the vent) during and immediately after the eruptions, and the cloud resembled an advected gravity current. Second, a much larger, highly elongated region marked by a secondary‐mass maximum occurred 150–350 km downwind in at least two of the three events. This was the result of aggregate fallout of a bimodal size distribution including fine (<25 μm) ash that quickly depleted the solid fraction of the volcanic cloud. For the first several hundred kilometers, the cloud spread laterally, first as an intrusive gravity current and then by wind shear and diffusion as downwind cloud transport occurred at the windspeed (during the first 18–24 h). Finally, the clouds continued to move through the upper troposphere but began decreasing in areal extent, eventually disappearing as ash and SO2 were removed by meteorological processes. Total SO2 in each eruption cloud increased by the second day of atmospheric residence, possibly because of oxidation of coerupted H2S or possibly because of the effects of sequestration by ice followed by subsequent SO2 release during fallout and desiccation of ashy hydrometeors. SO2 and volcanic ash travelled together in all the Spurr volcanic clouds. The initial (18–24 h) area expansion of the clouds and the subsequent several days of drifting were successfully mapped by both SO2 (ultraviolet) and ash (infrared) satellite imagery.

Volcanic ash

Tropopause

Vulcanian eruption

10.1086/323189

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Citations (104)

10 years of volcanic activity in Alaska; 1983 to 1992; a video

Antarctica A Keystone in a Changing World (1995)

Michael P. Doukas Robert G. McGimsey Joseph M. Dorava

10.3133/ofr9561a

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Catastrophic acid crater lake drainage, lahar, and acidic aerosol formation at Mount Chiginagak volcano, Alaska - Abstract

J. R. Schaefer William E. Scott Robert G. McGimsey Janet C. Jorgenson William C. Evans

An area of snow and ice 400 m wide and 105 m deep began melting at the summit crater of Mount Chiginagak volcano sometime between November 2004 and early May 2005, presumably due to increased heat flux from the hydrothermal system, or possible magma intrusion and degassing. In early May 2005, an estimated 3.8 x 106 m 3 of sulfurous, clay-rich debris and acidic water, with an accompanying acidic aerosol component, exited the crater through a tunnel at the base of a glacier that breaches the south crater rim. Over 27 km downstream, the acidic waters of the flood inundated an important salmon spawning drainage, acidifying Mother Goose Lake from surface to depth (approximately 0.5 km in volume with a pH of 2.9 to 3.1), killing all aquatic life, and preventing the annual salmon run. Crater lake water sampled 8 km downstream of the summit outflow after considerable dilution from glacial meltwater was a weak sulfuric acid solution (pH = 3.2, SO4 = 504 mg/L, CI = 53.6 mg/L, and F = 7.92 mg/L). The acid flood waters caused severe vegetation damage including plant death and leaf kill along the flood flow path. The flood was accompanied by an ambioructic flow of acidic aerosols that followed the flood flow-path, contributing to defoliation and necrotic leaf damage to vegetation in a 29 km 2 area along and above affected streams, in areas to heights of over 150 m in elevation above the drainage. Moss species killed in the event contained high levels of sulfur indicating an extremely elevated atmospheric sulfur content. The most abundant airborne phytotoxic constituents were likely wet sulfuric acid aerosols in possible combination with dry SO2 gas that were released during the catastrophic partial crater-lake drainage event. Two mechanisms of acidic aerosol formation are proposed: (1) generation of aerosol mist through turbulent flow of acidic water, and (2) catastrophic gas exsolution. This previously undocumented phenomenon of simultaneous vegetation-damaging acidic aerosols accompanying an acid crater lake drainage has important implications for the study of hazards associated with active volcanic crater lakes.

Crater lake

Meltwater

Source

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Emission rates of sulfur dioxide and carbon dioxide from Redoubt Volcano, Alaska during the 1989–1990 eruptions

Journal of Volcanology and Geothermal Research (1994)

Thomas J. Casadevall Michael P. Doukas Christina A. Neal Robert G. McGimsey Cynthia A. Gardner

Fumarole

Dome (geology)

10.1016/0377-0273(94)90050-7

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Citations (66)

2000 volcanic activity in Alaska and Kamchatka: summary of events and response of the Alaska Volcano Observatory

Antarctica A Keystone in a Changing World (2004)

Christina A. Neal Robert G. McGimsey O. S. Chubarova

10.3133/ofr20041034

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Citations (8)

2006 volcanic activity in Alaska, Kamchatka, and the Kurile Islands: Summary of events and response of the Alaska Volcano Observatory

Scientific investigations report (2008)

Christina A. Neal Robert G. McGimsey James P. Dixon Alexander Manevich Alexander Rybin

The Alaska Volcano Observatory (AVO) responded to eruptions, possible eruptions, and volcanic unrest at or near nine separate volcanic centers in Alaska during 2006. A significant explosive eruption at Augustine Volcano in Cook Inlet marked the first eruption within several hundred kilometers of principal population centers in Alaska since 1992. Glaciated Fourpeaked Mountain, a volcano thought to have been inactive in the Holocene, produced a phreatic eruption in the fall of 2006 and continued to emit copious amounts of volcanic gas into 2007. AVO staff also participated in hazard communication and monitoring of multiple eruptions at seven volcanoes in Russia as part of its collaborative role in the Kamchatka and Sakhalin Volcanic Eruption Response Teams.

Phreatic eruption

Volcanic hazards

Phreatic

Lahar

Unrest

10.3133/sir20085214

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Citations (29)

Preliminary volcano-hazard assessment for Akutan Volcano, east-central Aleutian Islands, Alaska

Antarctica A Keystone in a Changing World (1998)

Christopher F. Waythomas John A. Power D.H. Richter Robert G. McGimsey

Akutan Volcano is a 1100-meter-high stratovolcano on Akutan Island in the east-central Aleutian Islands of southwestern Alaska. The volcano is located about 1238 kilometers southwest of Anchorage and about 56 kilometers east of Dutch Harbor/Unalaska. Eruptive activity has occurred at least 27 times since historical observations were recorded beginning in the late 1700's. Recent eruptions produced only small amounts of fine volcanic ash that fell primarily on the upper flanks of the volcano. Small amounts of ash fell on the Akutan Harbor area during eruptions in 1911, 1948, 1987, and 1989. Plumes of volcanic ash are the primary hazard associated with eruptions of Akutan Volcano and are a major hazard to all aircraft using the airfield at Dutch Harbor or approaching Akutan Island. Eruptions similar to historical Akutan eruptions should be anticipated in the future. Although unlikely, eruptions larger than those of historical time could generate significant amounts of volcanic ash, fallout, pyroclastic flows, and lahars that would be hazardous to life and property on all sectors of the volcano and other parts of the island, but especially in the major valleys that head on the volcano flanks. During a large eruption an ash cloud could be produced that may be hazardous to aircraft using the airfield at Cold Bay and the airspace downwind from the volcano. In the event of a large eruption, volcanic ash fallout could be relatively thick over parts of Akutan Island and volcanic bombs could strike areas more than 10 kilometers from the volcano.

Volcanic ash

Lahar

Stratovolcano

Volcanic hazards

Peléan eruption

Submarine volcano

10.3133/ofr98360

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Citations (20)

Video of the August 18, 1992, eruption of Crater Peak vent on Spurr Volcano, Alaska

Antarctica A Keystone in a Changing World (1994)

Robert G. McGimsey Joseph M. Dorava

10.3133/ofr94614

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Citations (3)