USGS Volcano Notice - DOI-USGS-AVO-2025-04-25T17:41:02+00:00

Unrest continues at Mount Spurr, though at a lower level than seen in early 2025. The likelihood of an eruption has decreased from March, but the volcano remains at an elevated level of unrest and an explosive eruption (or eruptions) like those that occurred in 1953 and 1992 is still possible. We would expect to see weeks or more of more elevated unrest that would provide advance warning of an eruption.  

Seismicity remains above background rates, with 66 located earthquakes over the last week. These earthquakes are much smaller than those caused by tectonic activity and cannot be felt. Almost all from the past week are smaller than Magnitude 1. Earthquake rates have shown variability during this current period of unrest. In addition to located events, much smaller quakes are occurring several times per hour. Ground deformation at Mount Spurr has slowed over the past month, like the pause that occurred for several weeks in November and December 2024.  

AVO conducted two flights to the volcano this week. On Wednesday, April 23, the field crew was able to dig out monitoring station SPCN from deep snow but was unable to measure gas emissions due to high winds. Conditions yesterday, April 24, were more favorable, and field crews measured surface temperatures at the summit and Crater Peak using an infrared camera, measured gas emissions, and dug out and augmented the power system at station SPCG. Views of the summit show steaming from fumaroles on the upper flanks and along the shoreline of the crater lake. The lake remains mostly covered in floating ice. No significant surface changes were observed at Crater Peak. Gas data from the flight are still being processed, but emission rates appear broadly similar to or slightly lower than those measured in March.  

Sulfur dioxide emissions were detected in satellite data on April 19, 21, and 22. Steaming from the summit continues to be visible in web camera images during periods of clear viewing conditions. Snow is currently covering up the CKT web camera, but other web cameras (like SPCR) are snow free and functioning well. 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 that would allow advance warning.  

Activity at Great Sitkin Volcano continued over the past week, characterized by the slow eruption of lava in the summit crater. Satellite data from April 20 shows lava flow inflation on the southeast portion of the lava dome. A video taken April 9, recently shared with AVO, shows the steaming lava dome. Intermittent, small volcanic earthquakes continue to occur. Other satellite and web camera observations were mostly obscured by clouds over the past week.

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.