The 2008 phreatomagmatic eruption of Okmok volcano, Aleutian Islands, Alaska: Chronology, deposits, and landform changes
Okmok volcano, Aleutian Islands, Alaska, explosively erupted over a five-week period between July 12 and August 23, 2008. The eruption was predominantly phreatomagmatic, producing fine-grained tephra that covered most of northeastern Umnak Island. The eruption had a maximum Volcanic Explosivity Index (VEI) of 4, with eruption column heights up to 16 km during the opening phase. Several craters and a master tuff cone formed in the caldera as a result of phreatomagmatic explosions and accumulated tephra-fall and surge deposits. Ascending magma continuously interacted with an extensive shallow groundwater table in the caldera, resulting in the phreatomagmatic character of the eruption. Syneruptive explosion and collapse processes enlarged a pre-existing lake, created a second, entirely new lake, and formed new, deep craters. A field of ephemeral collapse pits and collapse escarpments formed where rapid groundwater withdrawal removed material from beneath capping lava flows. This was the first significant phreatomagmatic event in the U.S. since the Ukinrek Maars eruption in 1977.
Citation Information
Publication Year | 2015 |
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Title | The 2008 phreatomagmatic eruption of Okmok volcano, Aleutian Islands, Alaska: Chronology, deposits, and landform changes |
DOI | 10.14509/29405 |
Authors | Jessica Larsen, Christina A. Neal, Janet R. Schaefer, Max Kaufman, Zhong Lu |
Publication Type | Report |
Publication Subtype | Other Government Series |
Series Title | Alaska Division of Geological & Geophysical Surveys Report of Investigation |
Series Number | RI 2015-2 |
Index ID | 70147065 |
Record Source | USGS Publications Warehouse |
USGS Organization | Volcano Science Center |