Increased seismic activity and ground inflation at Mount Spurr, Alaska
Mount Spurr in Alaska remains in a state of volcanic unrest, with AVO detecting numerous shallow earthquakes on February 13, 2025, likely caused by magma movement beneath the volcano. While an eruption is not expected in the near term, ongoing activity suggests one could occur in the future, most likely at Crater Peak, which erupted explosively in 1953 and 1992.
The north flank of the summit cone of Mount Spurr with the Cook Inlet waters visible far in the background on February 7, 2025. Weak steam emissions are visible from the summit crater. Image credit: AVO/USGS
Mount Spurr remains in a state of volcanic unrest, with numerous shallow earthquakes detected beneath the volcano on February 13, according to the Alaska Volcano Observatory (AVO).
Recent seismic activity has been concentrated under Crater Peak and the summit, but no unusual surface activity has been observed in satellite or webcam imagery. In addition, a small steam plume was visible from the summit vent on AVO’s ANCW webcam.
AVO maintains the Aviation Color Code at Yellow and the Volcano Alert Level at Advisory, indicating ongoing but non-eruptive volcanic activity.
The ongoing unrest at Mount Spurr suggests that fresh magma has intruded into the crust beneath the volcano. Given past eruptions and the current patterns of seismic activity, ground deformation, and surface heating, several possible outcomes exist.
One scenario is that no eruption occurs, with the magma failing to reach the surface. In this case, the current unrest would gradually subside over weeks or months as earthquake activity decreases, deformation slows, and surface temperatures return to normal.
Another possibility is an eruption at Crater Peak, similar to those in 1953 and 1992. This would likely begin with increasing signs of unrest as magma ascends, culminating in one or more explosive events lasting from minutes to a few hours. Such an eruption would generate ash clouds capable of traveling hundreds of miles downwind, while pyroclastic flows, lahars, and ballistic projectiles would impact the area surrounding Mount Spurr.
A less likely scenario involves an eruption from the summit of Mount Spurr itself, a location with no known historical eruptions. A summit eruption would likely be explosive and could produce lava flows. The melting of glacial ice at higher elevations could trigger lahars and other hydrologic hazards.
At this time, based on available monitoring data, the AVO considers the first two scenarios—either no eruption or an eruption at Crater Peak—to be equally likely. An eruption from the summit remains a lower-probability event.
Should an eruption occur, the most likely site would be the Crater Peak vent, which erupted in 1992 and 1953. “It is less likely that an eruption would occur from Spurr summit, which last erupted several thousand years ago,” AVO said, adding that the past Crater Peak eruptions were often explosive, and far-traveled ash clouds and ashfall can be expected if an eruption occurs.
“We expect to see additional seismic activity, gas emissions, and surface heating, as well as changes to surface deformation before an eruption if one were to occur. Such stronger unrest may provide days to a few weeks of additional warning, but that is not certain.”
More than 2 700 earthquakes have been recorded since the unrest started 10 months ago, with the strongest being M2.9 on January 2, 2025.
Earthquake clusters have been identified at depths of 0 to 10 km (0 to 6.2 miles) and 12 to 22 km (7.5 to 13.7 miles) beneath both the summit and Crater Peak.
More than 260 earthquakes were detected between January 3 and January 10, 2025, with satellite radar data confirming the widening of summit crater crevasses.
Ground inflation was measured at 6 cm (2.4 inches), with modeling indicating that the deformation source is located 3 to 5 km (1.9 to 3.1 miles) below sea level and 3 to 4 km (1.9 to 2.5 miles) west of the summit.
The February 7, 2025, gas measurement flight detected low levels of sulfur dioxide (SO2) and carbon dioxide (CO2), consistent with previous readings from June and December 2024.
The current unrest began in March 2024, when GNSS data first detected sustained upward and outward deformation. Seismicity began increasing in April 2024, prompting AVO to raise Mount Spurr’s Aviation Color Code to Yellow and Alert Level to Advisory on October 16, 2024.
The largest earthquake in this period was recorded as M2.3 on October 6, 2024. A small summit crater lake, first observed in early summer, has since expanded.
Over 180 earthquakes were recorded between October 16 and November 1, 2024, some accompanied by volcanic tremors indicating potential deep fluid movement. On December 10, 2024, an M2.8 earthquake occurred beneath the summit, followed by further tremor episodes.
A gas measurement flight in late December 2024 detected H2O, SO2, H2S, and CO2 levels consistent with earlier observations. Imaging confirmed that the summit crater lake had expanded despite winter conditions. Crater Peak showed no unusual surface activity.
Mount Spurr is located 130 km (81 miles) west of Anchorage. It stands at 3 374 m (11 070 feet) and has a known eruptive history dating back to at least 6050 BCE.
The most recent confirmed eruptions were in 1953 and 1992, with both reaching Volcanic Explosivity Index (VEI) 4 and producing widespread ashfall.
References:
1 Mount Spurr – AVO/USGS – February 14, 2025
2 Mount Spurr – GVP – Accessed on February 14, 2025
Rishika holds a Master’s in International Studies from Stella Maris College, Chennai, India, where she earned a gold medal, and an MCA from the University of Mysore, Karnataka, India. Previously, she served as a Research Assistant at the National Institute of Advanced Studies, Indian Institute of Science, Bengaluru, India. During her tenure, she contributed as a Junior Writer for Europe Monitor on the Global Politics website and as an Assistant Editor for The World This Week. Her work has also been published in The Hindu newspaper, showing her expertise in global affairs. Rishika is also a recipient of the Women Empowerment Award at the district level in Haryana, India, in 2022.
Commenting rules and guidelines
We value the thoughts and opinions of our readers and welcome healthy discussions on our website. In order to maintain a respectful and positive community, we ask that all commenters follow these rules.