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Report on Shishaldin (United States) — 18 November-24 November 2015

Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 18 November-24 November 2015
Managing Editor: Sally Kuhn Sennert

Please cite this report as:

Global Volcanism Program, 2015. Report on Shishaldin (United States). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 18 November-24 November 2015. Smithsonian Institution and US Geological Survey.

Volcano Profile |  Weekly Report (18 November-24 November 2015)


Shishaldin

United States

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

All times are local (unless otherwise noted)


AVO reported that no anomalous activity at Shishaldin had been observed in satellite data since weakly elevated surface temperatures were detected on 16 October. In addition, low-amplitude seismic tremor continued but was likely not indicative of a continuing eruption. The Aviation Color Code was lowered to Yellow and the Volcano Alert Level was lowered to Advisory.

Geologic Background. The beautifully symmetrical volcano of Shishaldin is the highest and one of the most active volcanoes of the Aleutian Islands. The 2857-m-high, 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 steady steam plume rises from its small summit crater. Constructed atop an older glacially dissected volcano, it is Holocene in age and largely basaltic in composition. Remnants of an older ancestral volcano are exposed on the west and NE sides at 1500-1800 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)