USGS Volcano Notice - DOI-USGS-AVO-2025-06-16T19:22:55+00:00

Unrest continues at Mount Spurr volcano, with occasional, small volcanic earthquakes continuing to occur beneath the volcano. No noteworthy activity was seen in satellite or webcam images over the last 24 hours.

Although low-level unrest continues, no changes have been observed in the monitoring data to indicate that the volcano is moving closer to an eruption. Based on previous eruptions, changes from current activity in the earthquakes, ground deformation, summit lake conditions, and fumarolic activity would be expected if magma began to move closer to the surface. Therefore, if an eruption occurred, it would be preceded by additional signals allowing warning.

The volcano is monitored using local seismic, infrasound, web camera, and GNSS (GPS) stations along with regional infrasound, lightning networks, and satellite data.

Lava continues to erupt slowly in the summit crater of Great Sitkin Volcano. Seismicity remains at low levels with occasional small earthquakes detected, including signals possibly caused by small rockfalls from the growing summit lava dome. Weakly elevated surface temperatures were seen in one satellite view over the last 24 hours. Webcam views were obscured by clouds.

The current eruption of Great Sitkin Volcano began with a single explosive event in May 2021. The ongoing eruption of lava at the summit began shortly afterward, in July 2021. The volcano is monitored using local seismic and infrasound sensors, satellite data and web cameras, and regional infrasound and lightning networks.

An increase in seismicity at Iliamna that occurred yesterday morning ceased after a few hours, with no surface activity observed. 

The increase, which was marked by frequent small earthquakes, was observed beginning at about 4:30 am AKDT (12:30 UTC) yesterday, June 15, 2025. Initially, the earthquake rate was nearly continuous, with several earthquakes per minute, but then slowed to a rate of about one earthquake per minute, and finally returned to background at about 2:30 pm AKDT (22:30 UTC). 

This seismic activity was likely not caused by volcanic unrest. The seismicity resembled that previously observed preceding large ice and rock avalanches at the volcano. A short (less than one minute) seismic signal at the end of the sequence may have been caused by a small flowage event but no corresponding signal, such as was recorded for past large avalanches, was observed at the Kenai infrasound array. We also have no visual sign of an avalanche, though future high-resolution satellite images may provide more information. 

Iliamna remains at Aviation Color Code and Volcano Alert Level UNASSIGNED/UNASSIGNED because the monitoring network is down to a single station. As snowmelt occurs it is likely that the stations will come back online as power recovers. If outages persist we will conduct site visits to assess possible station damage and make repairs.