Report on Shishaldin (United States) — 8 January-14 January 2020
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 8 January-14 January 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, 8 January-14 January 2020. Smithsonian Institution and US Geological Survey.
54.756°N, 163.97°W; summit elev. 2857 m
All times are local (unless otherwise noted)
AVO summarized the 7 January eruptive activity at Shishaldin, characterizing the period of activity during 0500-1200 as the most sustained explosive activity of the eruptive sequence so far. Ash plumes drifted over 200 km ENE, were ash rich during 0900-1200, and caused several flight cancellations and minor ashfall in Cold Bay. Elevated surface temperatures continued to be identified in satellite images during 7-10 January, indicating lava effusion; seismicity decreased but remained above background levels. Satellite images acquired during 10-14 January showed weak surface temperatures, indicated cooling lava; seismicity remained above background levels.
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.