AVO Staff Directory:

Since 1988, the Alaska Volcano Observatory (AVO) has been monitoring volcanic activity across the state, conducting scientific research on volcanic processes, producing volcano-hazard assessments, and informing both the public and emergency managers of volcanic unrest. Below are some examples of the activity at Alaska's volcanoes that have held the attention of AVO staff.

Schaefer, J.R., and Nye, Chris, 2008, The Alaska Volcano Observatory - 20 years of volcano research, monitoring, and eruption response: Alaska Division of Geological & Geophysical Surveys, Alaska GeoSurvey News, NL 2008-001, v. 11, n. 1, p. 1-9, available at http://wwwdggs.dnr.state.ak.us/pubs/pubs?reqtype=citation&ID=16061 .
ADGGS website with link to PDF
full-text PDF on AVO's server : 5.68 MB

A mass of snow and ice 400-m-wide and 105-m-thick began melting in the summit crater of Mount Chiginagak volcano sometime between November 2004 and early May 2005, presumably owing to increased heat flux from the hydrothermal system, or possibly from magma intrusion and degassing.

Schaefer, J. R., W. E. Scott, W. C. Evans, J. Jorgenson, R. G. McGimsey, and B. Wang, 2008, The 2005 catastrophic acid crater lake drainage, lahar, and acidic aerosol formation at Mount Chiginagak volcano, Alaska, USA: Field observations and preliminary water and vegetation chemistry results: Geochemistry Geophysics Geosystems, v. 9, n. 7, 29 p., Q07018, doi:10.1029/2007GC001900.

Okmok volcano, in the central Aleutian arc, Alaska, produced two caldera-forming eruptions within the last ~12,000 years. This study describes the stratigraphy, composition, and petrology of those two eruptions. Both eruptions initially produced small volumes of felsic magmas, followed by voluminous andesite and basaltic andesite. The Okmok I eruption produced >30 km3 DRE of material on Umnak Island, and Okmok II ~15 km3.

Larsen, J. F., Neal, Christina, Schaefer, Janet, Beget, Jim, and Nye, Chris, 2007, Late Pleistocene and Holocene caldera-forming eruptions of Okmok Caldera, Aleutian Islands, Alaska, in Eichelberger, John, Gordeev, Evgenii, Izbekov, Pavel, Kasahara, Minoru, and Lees, Jonathan, eds., Volcanism and Subduction: The Kamchatka Region: Geophysical Monograph 172, American Geophysical Union, p. 343-364.

Schaefer, J. R., 2005, 30-meter shaded relief image of Okmok Volcano, Umnak Island, Alaska: Alaska Division of Geological & Geophysical Surveys Raw Data File RDF 2005-01, 1 CD-ROM.
MapInfo .TAB file : 1 KB
.TFW file : 1 KB
TIFF image file : 17.4 MB
image of shaded relief TIFF file : 26 KB
metadata for RDF 2005-01 : 23 KB

"Okmok Volcano is an active volcano located on the northeast end of Umnak Island, about 100 kilometers southwest of Dutch Harbor. The volcano is capped by a large, circular caldera, 10 kilometers in diameter and 500 to 800 meters deep, that formed during catastrophic eruptions about 12,000 and 2,000 years ago. Since then, more than a dozen separate vents within the caldera have erupted, some of them multiple times, to produce lava flows and widespread tephra (volcanic ash) deposits, with the most recent eruption occurring in 1997. Very large floods and lahars also have accompanied past eruptions, one of which destroyed an Aleut village in 1817. Multiple eruptions of lava and ash also have occurred from vents on the volcano's flanks. The volcano's long-term pattern of frequent eruptions, and dramatic intra-caldera deformation and accompanying seismicity since 1997 show that it remains active, and almost certainly will be the site of explosive and nonexplosive eruptions in the future. Understanding the variety of potential hazards associated with different types of volcanic processes typical of Okmok Volcano can help minimize the impacts of future eruptions."

Beget, J.E., Larsen, J.F., Neal, C.A., Nye, C.J., and Schaefer, J.R., 2005, Preliminary volcano-hazard assessment for Okmok Volcano, Umnak Island, Alaska: Alaska Division of Geological & Geophysical Surveys Report of Investigation 2004-3, 32 p., 1 sheet, scale 1:150,000.
full text of report : 3.4 MB
map sheet : 53.2 MB
link to all files for this report on DGGS website

Schaefer, Janet, and Nye, C. J., 2002, Historically active volcanoes of the Aleutian Arc: Alaska Division of Geological & Geophysical Surveys Miscellaneous Publication MP 0123, unpaged, 1 sheet, scale 1:3,000,000.
MrSID map sheet : 3.3 MB
page-size PDF : 700 KB
poster-size PDF : 4.87 MB

Shishaldin Volcano, in the central Aleutian volcanic arc, became seismically restless during the summer of 1998. Increasing unrest was monitored using a newly installed seismic network, weather satellites, and rare local visual observations. The unrest culminated in large eruptions on 19 April and 22-23 April 1999. The opening phase of the 19 April eruption produced a sub-Plinian column that rose to 16 km before rapidly dissipating. About 80 min into the 19 April event we infer that the eruption style transitioned to vigorous Strombolian fountaining. Exceptionally vigorous seismic tremor heralded the 23 April eruption, which produced a large thermal anomaly observable by satellite, but only a modest, 6-km-high plume.

Nye, C. J., Keith, T. E. C., Eichelberger, J. C., Miller, T. P., McNutt, S. R., Moran, S., Schneider, D. J., Dehn, J., and Schaefer, J. R., 2002, The 1999 eruption of Shishaldin Volcano, Alaska: monitoring a distant eruption: Bulletin of Volcanology, v. 64, n. 8, p. 507-519.

"Shishaldin Volcano is a 2,857-meter-high stratovolcano on Unimak Island, the most easterly of the Aleutian Islands. It is located about 45 kilometers west of False Pass, a small, permanently inhabited fishing village on Unimak Island that has a summer population of about 100. Shishaldin Volcano is historically one of the most active volcanoes in the Aleutian Islands. Eruptive events have occurred on at least 39 occasions since the late 1700s, when Russian traders and explorers began keeping written records. The most recent eruptive episode occurred from February to July of 1999, when the volcano produced tephra plumes on several occasions and extensive scoria blankets, and lahars on two occasions. The largest explosive eruption, on April 19, 1999, sent ash higher than 16 kilometers above sea level. The ash cloud drifted southward with the wind over the North Pacific Ocean, causing local disruptions in air traffic."

Beget, J. E., Nye, C. J., Schaefer, J. R., and Stelling, P. L., 2002, Preliminary volcano-hazard assessment for Shishaldin Volcano, Alaska: Alaska Division of Geological & Geophysical Surveys Report of Investigations RI 2002-4, 28 p., 1 sheet, scale 1:500,000.
full-text PDF : 2.25 MB

Schaefer, J. R. G., 2002, Stratigraphy, major oxide geochemistry, and 40Ar/39Ar geochronology of a tephra section near Tok, Alaska: University of Alaska Fairbanks unpublished M.S. thesis, 62 p.
full-text PDF : 2.06 MB