AVO summarized the 7 January eruptive activity at Shishaldin, characterizing the period of activity during 0500-1200 as the most sustained explosive activity of the eruptive sequence so far. Ash plumes drifted over 200 km ENE, were ash rich during 0900-1200, and caused several flight cancellations and minor ashfall in Cold Bay. Elevated surface temperatures continued to be identified in satellite images during 7-10 January, indicating lava effusion; seismicity decreased but remained above background levels. Satellite images acquired during 10-14 January showed weak surface temperatures, indicated cooling lava; seismicity remained above background levels.

Geological Summary. The symmetrical glacier-covered Shishaldin in the Aleutian Islands 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 edifice 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 covered 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.

Source: US Geological Survey Alaska Volcano Observatory (AVO)