Report on Shishaldin (United States) — 23 July-29 July 2014
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 23 July-29 July 2014
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2014. Report on Shishaldin (United States). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 23 July-29 July 2014. Smithsonian Institution and US Geological Survey.
54.756°N, 163.97°W; summit elev. 2857 m
All times are local (unless otherwise noted)
AVO reported that during 23-29 July low-level eruptive activity continued at Shishaldin volcano. Elevated surface temperatures at the summit were detected daily from satellite data. On 26 July satellite and web camera images showed trace dustings of ash over fresh snow in the immediate vicinity of the crater. Web camera images showed short dark streaks of possible debris flow deposits extending from the summit crater on the southeast flank, possibly the result of the melting of snow and ice near the summit due to the increased temperatures in the vicinity of the crater. Web camera and satellite images were mostly obscured due to clouds other days. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.
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.