AVO reported that unrest continued at Shishaldin during 22-28 November. Seismicity began to decrease on 21 November, though remained elevated with ongoing seismic tremor and small, low-frequency earthquakes recorded during the week. Elevated surface temperatures were identified in satellite images during 22 and 25-26 November. Robust steam emissions rising from the summit vent as well as from a scarp on the upper NE flank, near the summit were visible in satellite and webcam images drifting 50 km SSE during 25-26 November. During 27-28 November steam plumes were visible in webcam images and small explosions were observed in seismic and local infrasound data. Weather clouds often prevented views of the volcano. The Volcano Alert Level remained at Watch (the third level on a four-level scale) and the Aviation Color Code remained at Orange (the third color on a four-color scale).

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)