Report on Shishaldin (United States) — August 1976
Natural Science Event Bulletin, vol. 1, no. 11 (August 1976)
Managing Editor: David Squires.
Shishaldin (United States) Occasional steam seen during clear weather
Please cite this report as:
Global Volcanism Program, 1976. Report on Shishaldin (United States) (Squires, D., ed.). Natural Science Event Bulletin, 1:11. Smithsonian Institution. https://doi.org/10.5479/si.GVP.NSEB197608-311360.
54.756°N, 163.97°W; summit elev. 2857 m
All times are local (unless otherwise noted)
31 July (2045-2130): No activity.
2 August (1133-1145): No activity.
3 August (0755-2130): Light steam emission that intensified after 1600, turning to "smoke" after 2015. No new accumulations of ash were noted.
4 August (0730-0755): Steady plume of light steam.
12 August (1745-1800): Heavy steam blown down the W slope by winds.
22 August (0910-1205): No activity.
30 August (0800-0930): No activity; 90% of the ash accumulation had been blown away.
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.
Information Contacts: R. Dean, USAF, Cold Bay.