Report on Shishaldin (United States) — April 1986
Scientific Event Alert Network Bulletin, vol. 11, no. 4 (April 1986)
Managing Editor: Lindsay McClelland.
Shishaldin (United States) Increased steam and ash emission
Please cite this report as:
Global Volcanism Program, 1986. Report on Shishaldin (United States) (McClelland, L., ed.). Scientific Event Alert Network Bulletin, 11:4. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198604-311360
54.756°N, 163.97°W; summit elev. 2857 m
All times are local (unless otherwise noted)
Anomalously large steam plumes with traces of ash have been noted for the past several months at Shishaldin by airline pilots and passengers. Diffuse ash layers extended from the volcano on 19 and 28 March, and steam and ash emission was seen on 6-7 May. Activity was less intense the next day, and had declined to minor steaming by 10 and 13 May. [See also 11:05].
Geological Summary. The symmetrical glacier-covered Shishaldin is the highest and one of the most active volcanoes of the Aleutian Islands. It is the westernmost of three large stratovolcanoes in the eastern half of Unimak Island. The Aleuts named the volcano Sisquk, meaning "mountain which points the way when I am lost." Constructed atop an older glacially dissected edifice, 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. A steam plume often rises from the summit crater.
Information Contacts: J. Reeder, ADGGS.