Geologists are closely monitoring Mount Spurr in the Aleutian Arc of Alaska, USA, after continued volcanic unrest. The Alaska Volcano Observatory (AVO) monitoring the situation says that an eruption is possible in the coming days and weeks.
Mount Spurr is an ice and snow-covered stratovolcano complex, meaning that it is a large, cone-shaped volcano formed by lava flows, pyroclastic deposits, mudflow deposits, and lava domes. The volcano has erupted twice in recorded history: once in 1953 and once in 1992. These eruptions came from the Crater Peak flank vent 3.5 kilometers (2 miles) south of the peak’s summit, rather than from Mount Spurr itself.
“These eruptions were relatively small but explosive, and they dispersed volcanic ash over areas of interior, south-central, and southeastern Alaska. Individual ash clouds produced by the 1992 eruption drifted east, north, and south. Within a few days of the eruption, the south-moving ash cloud was detected over the North Atlantic,” the US Geological Survey (USGS) explains of the volcano.
“Pyroclastic flows that descended the south flank of Crater Peak during both historical eruptions initiated volcanic-debris flows or lahars that formed temporary debris dams across the Chakachatna River, the principal drainage south of Crater Peak. Prehistoric eruptions of Crater Peak and Mount Spurr generated clouds of volcanic ash, pyroclastic flows, and lahars that extended to the volcano flanks and beyond.”
Since April 2024, there has been an increase in the number of earthquakes detected beneath the volcano, to around 30 a week. While this doesn’t necessarily indicate an eruption is imminent, activity increased again in October 2024, and between then and February 6, there have been around 125 earthquakes detected beneath the volcano per week. The largest of these, detected on January 2, was of magnitude 2.9.
“The current unrest at Mount Spurr strongly suggests that new magma has intruded into the crust beneath the volcano,” AVO said in a February 6 statement.
AVO believes that a few scenarios are possible, given the recent activity. One is that no magma reaches the surface, and the earthquakes subside over the course of several months.
Another is that there is an eruption similar in magnitude to the 1953 and 1992 eruptions. This scenario would see “one or more explosive events lasting one or a few hours [that] would produce ash clouds carried downwind for hundred of miles, and the uninhabited area around Mount Spurr would be inundated by pyroclastic flows, mudflows (lahars), and ballistic showers.”
The first two scenarios are considered to be equally likely at this time. A further, though less likely, scenario is that there is an eruption at the summit of Mount Spurr itself.
“An eruption from the summit vent of Mount Spurr could occur, though there have been none in historical times,” AVO explained. “Such an eruption would likely be explosive and may also form lava flows. A summit eruption also would likely melt large volumes of glacial ice, which could lead to lahars and other hydrologic hazards.”
Thankfully, there are no nearby towns or cities that would be in the path of pyroclastic flows and mudflows. However, the lead of AVO, Matt Haney of the USGS, told Live Science that an eruption could cause disruption for flights in the area.
The team continues to monitor activity at the volcano using webcams, a seismic network, ground deformation stations, and infrasound sensors. More data will hopefully tell us whether an eruption is indeed imminent.
