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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...
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The 2009 eruption of Redoubt Volcano included 19 major tephra-producing explosions. Mass per unit area (MPUA) ash fall sampling of the resulting deposits allowed us to create isomass contours of the ash fall. This dataset contains the vector digital shapefiles of the ash fall contours for the explosive events. In addition, a point digital shapefile is included that describes more than 400 ash fall samples that were collected. For a detailed account of the 2009 eruption of Redoubt Volcano, see Schaefer, J.R., ed., 2012, The 2009 eruption of Redoubt Volcano, Alaska, with contributions by Bull, Katharine, Cameron, Cheryl, Coombs, Michelle, Diefenbach, Angie, Lopez, Taryn, McNutt, Steve, Neal, Christina, Payne, Allison,...
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Fisher volcano, containing the largest Holocene caldera in the Aleutian volcanic arc, is an active volcano near the center of Unimak Island, about 120 kilometers southwest of Cold Bay and about 175 kilometers northeast of Dutch Harbor. The volcano is composed of numerous small volcanic centers around and within a large, oval caldera 12 by 18 kilometers in diameter and 500 to 1,000 meters deep that formed during a catastrophic eruption about 9,400 years ago. Since then, more than 30 separate vents inside and outside the caldera have erupted; the most recent eruption occurred in 1826. These eruptions have produced lava flows and widespread tephra (volcanic ash) deposits, and have occasionally been accompanied by large...


    map background search result map search result map Ash fall contour map of the 2009 eruption of Redoubt Volcano, Alaska: Digital shapefiles of contours and sample locations Preliminary volcano-hazard assessment for Fisher volcano, Unimak Island, Alaska The 2008 phreatomagmatic eruption of Okmok Volcano, Aleutian Islands, Alaska: Chronology, deposits, and landform changes The 2008 phreatomagmatic eruption of Okmok Volcano, Aleutian Islands, Alaska: Chronology, deposits, and landform changes Preliminary volcano-hazard assessment for Fisher volcano, Unimak Island, Alaska Ash fall contour map of the 2009 eruption of Redoubt Volcano, Alaska: Digital shapefiles of contours and sample locations