Report on Shishaldin (United States) — 13 January-19 January 2021
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
13 January-19 January 2021
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2021. Report on Shishaldin (United States). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 13 January-19 January 2021. Smithsonian Institution and US Geological Survey.
54.756°N, 163.97°W; summit elev. 2857 m
All times are local (unless otherwise noted)
AVO reported that several outages affected GPS, seismic, and infrasound stations used to monitor Shishaldin. On 15 January AVO changed both the Aviation Color Code and the Volcano Alert Level to Unassigned, reflecting the lack of this data to detect unrest. The volcano continued to be monitored with local webcams, satellite data, and remote infrasound, seismic, and lightning networks.
Geological Summary. 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.