USGS Volcano Notice - DOI-USGS-AVO-2025-04-11T15:09:51+00:00

Volcanic unrest continues at Mount Spurr volcano and is characterized by ongoing earthquake activity. Seismicity remains elevated with about 55 located earthquakes over the last week. While this is similar to the previous week, earthquake rates have shown variability during this current period of unrest. Ground deformation at Mount Spurr has paused over the last couple of weeks, like the pause in deformation observed for several weeks this past November and December. No sulfur dioxide emissions were detected in satellite data over the past week. AVO is planning to do an overflight of the volcano to measure gas emissions on the next good weather day. High resolution satellite data from April 6 and 8 show some collapsing of ice from the summit crater wall, adding ice to the crater lake and some small snow avalanches, which are common this time of year. Cloudy conditions prevented views of the volcano most of the week. The Mount Spurr monitoring network is functioning well.  New snowfall this week has covered up the CKT web camera but other web cameras (like SPCR) are snow free and functioning well.

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 stations, web cameras, regional infrasound, lightning networks, and satellite data. 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. Intermittent, small volcanic earthquakes continue to occur. Weakly elevated surface temperatures were observed throughout the week in satellite data consistent with slow lava effusion. Steaming from the summit was observed April 9 and 10 in web camera imagery.

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.

On two occasions this week, April 6-7 and 8-9, strong northwesterly winds near Katmai and the Valley of Ten Thousand Smokes picked up loose volcanic ash from the 1912 Novarupta-Katmai eruption and carried it southeast. The National Weather Service issued SIGMETs for these low-level events and suggested that the maximum cloud height was 6,000 ft (1.8 km) and 5,000 ft (1.5 km) above sea level.

This phenomenon is not the result of recent volcanic activity and occurs during times of high winds and dry snow-free conditions in the Katmai area and other young volcanic areas of Alaska. No eruption is in progress. All volcanoes of the Katmai area (Trident, Snowy, Griggs, Katmai, Novarupta, Mageik, Martin) remain at color code GREEN. Resuspended volcanic ash should be considered hazardous and could be damaging to aircraft and health.

Resuspended volcanic ash should be considered hazardous and could be damaging to aircraft and health. For more information on volcanic ash and human health, visit the following website: http://volcanoes.usgs.gov/ash/. Official warnings about these ash resuspension events are issued by the National Weather Service: http://www.weather.gov/afc. Forecasts of airborne ash hazard to aircraft: http://www.weather.gov/aawu . Volcanic Ash Advisories: http://vaac.arh.noaa.gov/ . Forecasts of ash fall: http://www.weather.gov/afc. Air quality hazards and guidance from Alaska Department of Environmental Conservation, Division of Air Quality: http://dec.alaska.gov/Applications/Air/airtoolsweb/Advisories/Index