Lava and a possible new cone in Shishaldin’s summit crater were visible in a satellite image on 14 March prompting AVO to raise the Volcano Alert Level to Watch and the Aviation Color Code to Orange. Weak but elevated seismicity was also recorded along with small explosion signals during 14-17 March. Elevated surface temperatures, consistent with lava in the summit crater, were identified in satellite images during 15-17 March. A small steam plume rising from the summit crater was visible in a webcam image on 17 March.

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)