Report on Shishaldin (United States) — 13 August-19 August 2014
Smithsonian Institution / US Geological Survey
Weekly Volcanic Activity Report, 13 August-19 August 2014
Managing Editor: Sally Sennert.
Please cite this report as:
Global Volcanism Program, 2014. Report on Shishaldin (United States) (Sennert, S, ed.). Weekly Volcanic Activity Report, 13 August-19 August 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 13-19 August eruptive activity continued at Shishaldin volcano. Infrasound sensors located at Dillingham and on Akutan Island detected sound waves from the direction of Shishaldin that are consistent with low-level activity at the volcano. On 13 August a pilot reported a low-level plume from Shishaldin. On the evening of 16 August web camera views showed a steam and gas plume. On 17-19 August elevated surface temperatures were detected in partly cloudy satellite views. Other days satellite and web camera views were obscured by weather. No significant activity was noted in seismic data. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.
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.