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Report on Shishaldin (United States) — 25 March-31 March 2020

Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 25 March-31 March 2020
Managing Editor: Sally Kuhn Sennert

Please cite this report as:

Global Volcanism Program, 2020. Report on Shishaldin (United States). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 25 March-31 March 2020. Smithsonian Institution and US Geological Survey.

Volcano Profile |  Weekly Report (25 March-31 March 2020)


Shishaldin

United States

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

All times are local (unless otherwise noted)


AVO reported elevated seismicity at Shishaldin during 25-31 March characterized by continuous low-level tremor. Steam-and-gas plumes rising from the summit crater were occasionally recorded by the webcam and identified in satellite images. Weakly- to- moderately elevated surface temperatures were identified in satellite images during 29-30 March. The Volcano Alert Level remained at Watch and the Aviation Color Code remained at Orange.

Geologic Background. The beautifully symmetrical Shishaldin is the highest and one of the most active volcanoes of the Aleutian Islands. The glacier-covered volcano is the westernmost of three large stratovolcanoes along an E-W line in the eastern half of Unimak Island. The Aleuts named the volcano Sisquk, meaning "mountain which points the way when I am lost." A steam plume often rises from its small summit crater. Constructed atop an older glacially dissected volcano, it is largely basaltic in composition. Remnants of an older ancestral volcano 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 blanketed 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.

Source: US Geological Survey Alaska Volcano Observatory (AVO)