Skip to main content
Advanced Search

Filters: Tags: Volcaniclastics (X) > partyWithName: Schaefer, J.R. (X)

4 results (186ms)   

View Results as: JSON ATOM CSV
thumbnail
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...
thumbnail
Mount Chiginagak is a hydrothermally active volcano on the Alaska Peninsula, approximately 170 km south-southwest of King Salmon, Alaska. This small stratovolcano, approximately 8 km in diameter, has erupted through Tertiary to Permian sedimentary and igneous rocks. The eruptive products of Chiginagak volcano record a history of chiefly andesite lava flows and associated block-and-ash flows. The oldest lavas exposed are Pleistocene in age and are found everywhere around the edifice except in the northeast sector, where Holocene lava flows dominate the landscape. Holocene activity has covered the northeast flank with rubbly-topped andesite lava flows that extend as far as 4.6 km from their source vent at the summit...
thumbnail
Mount Chiginagak is a hydrothermally active volcano on the Alaska Peninsula, approximately 170 km south-southwest of King Salmon, Alaska. This small stratovolcano, approximately 8 km in diameter, has erupted through Tertiary to Permian sedimentary and igneous rocks. The eruptive products of Chiginagak volcano record a history of chiefly andesite lava flows and associated block-and-ash flows. The oldest lavas exposed are Pleistocene in age and are found everywhere around the edifice except in the northeast sector, where Holocene lava flows dominate the landscape. Holocene activity has covered the northeast flank with rubbly-topped andesite lava flows that extend as far as 4.6 km from their source vent at the summit...
thumbnail
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 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 Geologic map of Mount Chiginagak volcano, Alaska Geologic map of Mount Chiginagak volcano, Alaska Geologic map of Mount Chiginagak volcano, Alaska Geologic map of Mount Chiginagak volcano, Alaska 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