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Report on Shishaldin (United States) — December 1995


Shishaldin

Bulletin of the Global Volcanism Network, vol. 20, no. 11 (December 1995)
Managing Editor: Richard Wunderman.

Shishaldin (United States) Eruption sends ash plume above 10 km altitude

Please cite this report as:

Global Volcanism Program, 1995. Report on Shishaldin (United States) (Wunderman, R., ed.). Bulletin of the Global Volcanism Network, 20:11. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN199512-311360



Shishaldin

United States

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

All times are local (unless otherwise noted)


Based on satellite imagery and pilot reports received by the U.S. Federal Aviation Administration, an eruption began at 1830 on 23 December. Between 1830 and 2000 on 23 December, pilots reported an ash plume as high as 10.5 km altitude (35,000 feet); prevailing winds carried the plume primarily N and NW. Analysis of a satellite image from 1912 showed a possible small ash plume extending ~50 km NW. Possible very light ashfall was reported at approximately 0130 on 24 December in Cold Bay, 90 km NE; this ash would have been carried by westerly low-altitude winds.

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.

Information Contacts: Alaska Volcano Observatory.