A visual observation of a small steam-and-ash plume was made by the U.S. National Weather Service at 1535 on 2 June from Cold Bay (90 km NE); the plume rose 300-450 m above the summit and drifted ~8 km downwind to the N. Installation of a seismic network of six stations was completed in July; testing and data collection to determine background seismicity is expected to be completed by mid-November.

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.

Information Contacts: Alaska Volcano Observatory.