Report on Shishaldin (United States) — September 1997
Bulletin of the Global Volcanism Network, vol. 22, no. 9 (September 1997)
Managing Editor: Richard Wunderman.
Shishaldin (United States) Small steam-and-ash plume on 2 June
Please cite this report as:
Global Volcanism Program, 1997. Report on Shishaldin (United States). In: Wunderman, R. (ed.), Bulletin of the Global Volcanism Network, 22:9. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN199709-311360.
54.756°N, 163.97°W; summit elev. 2857 m
All times are local (unless otherwise noted)
A visual observation of a small steam-and-ash plume was made by the U.S. National Weather Service at 1535 on 2 June from Cold Bay (90 km NE); the plume rose 300-450 m above the summit and drifted ~8 km downwind to the N. Installation of a seismic network of six stations was completed in July; testing and data collection to determine background seismicity is expected to be completed by mid-November.
Geologic Background. The beautifully symmetrical volcano of Shishaldin is the highest and one of the most active volcanoes of the Aleutian Islands. The 2857-m-high, 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 steady steam plume rises from its small summit crater. Constructed atop an older glacially dissected volcano, it is Holocene in age and largely basaltic in composition. Remnants of an older ancestral volcano are exposed on the west and NE sides at 1500-1800 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.