Mount Okmok is a volcano on eastern Umnak Island, in the central-eastern Aleutian Islands of Alaska. Part of the Aleutian Volcanic Arc, it was formed by the subduction of the oceanic Pacific Plate under the North American Plate. Okmok is a large shield volcano capped by a 10-kilometer (6.2 mi) wide caldera. The caldera contains numerous cinder cones, their lava flows, and a few lakes. Okmok erupts mainly basaltic lava, mostly from the cones within the caldera.
Activity began in the Pleistocene. Two large caldera-forming eruptions took place during the Holocene, with a volcanic explosivity index (VEI) of 6; the second of these occurred in 43 BCE and caused a volcanic winter that might have changed the history of Egypt. After this second caldera-forming eruption a crater lake formed in the caldera, and drained in one of the largest known floods of the Holocene. Okmok is one of the most active volcanoes of North America; numerous eruptions have produced lava flows within the caldera, and the 1817 eruption destroyed an Aleut village.
The last eruption was in 2008 and produced several new vents in the caldera. This eruption, which occurred with little forewarning, yielded a volcanic cloud that produced volcanic ash fall around Okmok. The volcano is monitored by the Alaska Volcano Observatory (AVO).
MountOkmok is a volcano on eastern Umnak Island, in the central-eastern Aleutian Islands of Alaska. Part of the Aleutian Volcanic Arc, it was formed...
the United States. The island is home to a large volcanic caldera on MountOkmok and the only field of geysers in Alaska. It is separated from Unalaska...
Recheshnoi and MountOkmok. The most recent eruption of Mount Recheshnoi was on the flank of the volcano around 3,000 years ago. "Mount Recheshnoi Geyser...
(January 27, 2010). "Aerosol layers from the 2008 eruptions of MountOkmok and Mount Kasatochi; in situ upper troposphere and lower stratosphere measurements...
Kiska Korovin Volcano Mount Kukak Mount Kupreanof Mount Mageik Makushin Volcano Mount Martin Novarupta Nunivak Island MountOkmokMount Pavlof Pavlof Sister...
caused by volcano-tectonic earthquakes have also occurred at Mount Yasur in 1878, MountOkmok in 1878 and Kharimkotan in 1933. Earthquakes caused by tectonic...
Alaska. Other large caldera-forming eruptions in Alaska took place at MountOkmok, Fisher Caldera, and Veniaminof, with lesser events at Kaguyak and Black...
Dalrymple, G. B.; Smith, R. L. (March 1994). "Eruptive history and petrology of Mount Drum volcano, Wrangell Mountains, Alaska". Bulletin of Volcanology. 56 (1):...
within Katmai National Park and Preserve Okmok Caldera on Umnak Island in the Fox Islands group (includes MountOkmok, Jag Peak and Tulik Volcano) Pavlof Volcano...
Korea border Mount Aso crater lake, Japan Taal volcano, Philippines Lake Pinatubo, Philippines, formed after the 1991 eruption of Mount Pinatubo Kerið...
Island Mount Muir Mount Nagishlamina Mount Natazhat PB Mount Neacola PB Mount Newhall Mount Ogilvie MountOkmok, active shield volcano Mount O'Neel Mount Osborn...
definite place within the landscape. On Saturday July 12, 2008, nearby MountOkmok, erupted, sending ash 50,000 feet in the air and forcing the evacuation...
(2005-07-01). "Physical volcanology of the 2,050 bp caldera-forming eruption of Okmok volcano, Alaska". Bulletin of Volcanology. 67 (6): 497–525. doi:10.1007/s00445-004-0391-5...
definite place within the landscape. On Saturday July 12, 2008, nearby MountOkmok, erupted, sending ash 50,000 feet in the air and forcing the evacuation...
and the popularity of Yellowstone National Park, and Muschalik considers Mount Rainier to be just as dangerous as Kilauea due to its proximity to large...
Sepp (2020-07-07). "Extreme climate after massive eruption of Alaska's Okmok volcano in 43 BCE and effects on the late Roman Republic and Ptolemaic Kingdom"...
Gerding, M. (2010-09-17). "Aerosol layers from the 2008 eruptions of MountOkmok and Mount Kasatochi: In situ upper troposphere and lower stratosphere measurements...
exploring the Umnak Pass. It is 8 miles (13 km) by 6 miles (10 km) in area. Okmok Caldera Binalik Crater is located on Nunivak Island. It was named by the...
Peder (7 July 2020). "Extreme climate after massive eruption of Alaska's Okmok volcano in 43 BCE and effects on the late Roman Republic and Ptolemaic Kingdom"...
to say for certain whether Egypt would have become a Roman province if Okmok volcano (in modern-day Alaska) had not erupted, the eruption likely hastened...
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