AVO reported that several outages affected GPS, seismic, and infrasound stations used to monitor Shishaldin. On 15 January AVO changed both the Aviation Color Code and the Volcano Alert Level to Unassigned, reflecting the lack of this data to detect unrest. The volcano continued to be monitored with local webcams, satellite data, and remote infrasound, seismic, and lightning networks.

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)