Report on Shishaldin (United States) — June 1976
Natural Science Event Bulletin, vol. 1, no. 9 (June 1976)
Managing Editor: David Squires.
Shishaldin (United States) Steaming observed; flanks about 70% ash-covered
Please cite this report as:
Global Volcanism Program, 1976. Report on Shishaldin (United States) (Squires, D., ed.). Natural Science Event Bulletin, 1:9. Smithsonian Institution. https://doi.org/10.5479/si.GVP.NSEB197606-311360
54.756°N, 163.97°W; summit elev. 2857 m
All times are local (unless otherwise noted)
3 June (1100-1700): Volcano quiet; cone darkened by ash or exposed rock due to melted snow.
4 June (0800-2000): Steamed at irregular intervals and occasionally threw out ash that settled onto the slopes. The visible flanks appeared to be about 70% ash covered.
5 June (1400-2100): No activity noted.
6 June (1710-1730): No activity noted.
10 June (1430): Emitting black smoke intermittently. At 2000: the cone's upper 600 m, visible above the clouds, was extensively ash-covered; no activity noted.
11 June (1100-2000): Constantly emitting a weak steam plume.
12 June (0800-2000): Emitting a slight steam plume.
15 June (0500-0600, 2100): Steaming constantly.
19 June (1530): Steaming.
22 June (1300): Peak covered by recent snows. NE flank showed ashfall.
27 June (1100-1400): Entire cone from the 1,500 m level to the summit was lightly to heavily ash-covered.
28 June (1700-1730): Steaming weakly.
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: P. Sventek, USAF, Cold Bay.