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Report on Shishaldin (United States) — 7 February-13 February 2018


Shishaldin

Smithsonian Institution / US Geological Survey
Weekly Volcanic Activity Report, 7 February-13 February 2018
Managing Editor: Sally Sennert.

Please cite this report as:

Global Volcanism Program, 2018. Report on Shishaldin (United States) (Sennert, S, ed.). Weekly Volcanic Activity Report, 7 February-13 February 2018. Smithsonian Institution and US Geological Survey.

Weekly Report (7 February-13 February 2018)

Shishaldin

United States

54.756°N, 163.97°W; summit elev. 2857 m

All times are local (unless otherwise noted)


On 7 February AVO reported that seismic and infrasound activity from Shishaldin declined to background levels during the previous month, prompting the observatory to lower the Aviation Color Code to Green and the Volcano Alert Level to Normal.

Geological Summary. The symmetrical glacier-covered Shishaldin in the Aleutian Islands is the westernmost of three large stratovolcanoes in the eastern half of Unimak Island. The Aleuts named the volcano Sisquk, meaning "mountain which points the way when I am lost." Constructed atop an older glacially dissected edifice, it is largely basaltic in composition. Remnants of an older edifice are exposed on the W and NE sides at 1,500-1,800 m elevation. There are over two dozen pyroclastic cones on its NW flank, which is covered by massive aa lava flows. Frequent explosive activity, primarily consisting of Strombolian ash eruptions from the small summit crater, but sometimes producing lava flows, has been recorded since the 18th century. A steam plume often rises from the summit crater.

Source: US Geological Survey Alaska Volcano Observatory (AVO)