Alaska Volcano Observatory

Activity at Great Sitkin Volcano continued over the past week with slow eruption of lava in the summit crater and occasional small earthquakes. Satellite and web camera observations were obscured by clouds over most of the past week but weakly elevated surface temperatures consistent with lava emissions were observed in satellite views on May 29. A clear satellite view of the summit on May 30 showed minor steam emissions.
 
Since the May 2021 explosion, there have been no other explosions at Great Sitkin Volcano. The lava eruption that began in July 2021 is ongoing. It has filled most of the summit crater and advanced into valleys below. The volcano is monitored using local seismic and infrasound sensors, satellite data and web cameras, and regional infrasound and lightning networks.

Unrest continues at Mount Spurr. The level of activity is still above background, but lower than observed in early 2025. This decrease in activity suggests that the magma intrusion beneath Mount Spurr has stalled. The likelihood of an eruption has declined since March, but fluctuations in unrest are not uncommon, and explosive eruptions like those in 1953 and 1992 are still possible. Should unrest escalate, we expect increases in seismic activity, gas emissions, surface deformation, and surface heating. AVO released an Information Statement on May 28 that summarized and updated observations, interpretations, and possible outcomes.
 
AVO conducted a flight to Mount Spurr on Friday, May 23 to measure gas emissions and make observations. Observed emissions were similar in composition but at a slightly lower emissions rate than observed during the previous gas flight on April 24. Low level sulfur dioxide emissions were detected in satellite data this week. Ground deformation at Mount Spurr has paused over the past month, like the pause that occurred for several weeks in November and December 2024. Although it has paused over the past month, an apparent increase in observed deformation over the past few weeks is likely due to seasonal environmental factors affecting the equipment and not magmatic movement. During the past week, 119 earthquakes were located with most of them smaller than magnitude 1. This is a slight increase in located earthquakes compared to the previous eight weeks. Smaller quakes that cannot be located also occur several times per hour.
 
Views of the summit from local web cameras showed a vapor plume when viewing conditions were clear. No significant surface changes were observed at Mount Spurr over the past week. A recently established livestream of Mount Spurr, as viewed from Glen Alps in Anchorage, is available here: Mount Spurr Live Stream (ANCG). 

AVO continues to closely monitor activity at Mount Spurr for signals indicating the volcano is moving closer to an eruption using local seismic, infrasound, and GNSS (GPS) stations, web cameras, airborne and satellite gas measurements, regional infrasound, lightning networks, and satellite images. Based on previous eruptions, additional changes in earthquakes, ground deformation, the summit lake, and fumaroles would be expected if magma moves closer to the surface. Therefore, if an eruption occurred, it would be preceded by additional signals allowing advance warning.