Report on Shishaldin (United States) — October 1993
Bulletin of the Global Volcanism Network, vol. 18, no. 10 (October 1993)
Managing Editor: Edward Venzke.
Shishaldin (United States) Steam plume observed rising to 1,800 m above the summit
Please cite this report as:
Global Volcanism Program, 1993. Report on Shishaldin (United States) (Venzke, E., ed.). Bulletin of the Global Volcanism Network, 18:10. Smithsonian Institution.
54.756°N, 163.97°W; summit elev. 2857 m
All times are local (unless otherwise noted)
A steam plume up to 1,800 m above the volcano was reported by pilots on 28 October. That same day, observers from Izembeck National Wildlife Refuge reported a steam-and-ash plume that rose to 1,200 m above the summit and drifted SE.
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: Alaska Volcano Observatory.