AVO reported that unrest at Shishaldin continued during 25-31 October with observations suggesting ongoing degassing of magma at shallow levels beneath the summit. Seismicity was elevated, consisting of seismic tremor and small, low-frequency earthquakes, though activity had begun to slowly decline after the last explosive event on 3 October. Minor steam emissions were visible in webcam images during 24-25 October. Elevated surface temperatures were identified in satellite data during 28-29 October, though they did not indicate lava at the surface. On 31 October the Volcano Alert Level was lowered to Advisory (the second level on a four-level scale) and the Aviation Color Code was lowered to Yellow (the second 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)