USGS Volcano Notice - DOI-USGS-AVO-2025-10-02T18:09:35+00:00

Lava continues to erupt in the summit crater of Great Sitkin Volcano. Satellite data through September 30 showed continued slow advance of the lava from the vent, spreading to the southwest and southeast. Rockfalls from the step flow front continue and are traveling up to several hundred meters (~650 ft) down slope. Small earthquakes and rockfall signals were observed over the past day. Elevated surface temperatures continue to be observed. Webcam views were obscured by clouds over the past day. 

The current lava eruption began in July 2021 and since then has filled most of the summit crater and advanced into valleys below. There have been no explosions at Great Sitkin Volcano since an event in May 2021. The volcano is monitored using local seismic and infrasound sensors, satellite data and web cameras, and regional infrasound and lightning networks.

Frequent small earthquakes and infrasound signals, possibly caused by gas bubbles bursting deep within the crater, were detected over the past day. Typical steam emissions from the summit crater were observed in webcam images from this morning. High clouds yesterday afternoon prevented the satellite-based detection of sulfur dioxide gas emissions that have been prevalent over the past several months. 

Local seismic and infrasound sensors, web cameras, and a geodetic network are used to monitor Shishaldin Volcano. In addition to the local monitoring network, AVO uses nearby geophysical networks, regional infrasound and lighting data, and satellite images to detect eruptions.