Scientists have warned that a massive volcano in Alaska has a 50-50 chance erupting in the near future.
The 11,000-foot-tall Mount Spurr sits 77 miles from Anchorage— the state’s largest city which is home to nearly 300,000 people.
Over the last 10 months, it has been experiencing an unusually high amount of small earthquakes.
Since the seismic activity first began in April 2024, the rate of earthquakes has increased from an average of 30 per week to an average of 125 per week, ramping up in early October.
Experts at the Alaska Volcano Observatory (AVO) believe this seismic activity is being driven by new magma churning beneath the volcano, which could be a sign that it is getting ready to erupt.
If Mount Spurr does erupt, it could produce explosive plumes of ash, destructive mudslides called lahars and avalanches of hot gas, ash and rock called pyroclastic flows, which would race down the volcano’s side at over 200 mph.
Fortunately, there are not any communities within the potential path of pyroclastic flows or lahars from Mount Spurr.
But the amount of ash that would spew forth from this volcano could pose a threat to human health, causing breathing difficulties and releasing toxins linked to cancer.
Mount Spurr, an 11,000-foot-tall volcano, sits 77 miles from Anchorage, Alaska. An uptick in seismic activity over the last 10 minutes has scientists on alert for an imminent eruption
The last time Mount Spurr blew was in 1992, when it awoke from 39 years of dormancy after 10 months of elevated seismic activity.
That eruption emanated from the volcano’s Crater Peak side vent — an opening located on the side of the volcano — and produced a column of ash that rose 65,000 feet above sea level.
About a quarter-inch of ask accumulated in Anchorage, prompting residents to stay inside or wear masks when venturing outdoors.
And because volcanic ash particles are angular and sharp enough to cause jet engines to shut down, Anchorage and other nearby airports were forced to close until the skies cleared.
‘Today there are even more flights coming in and out of the Anchorage airport, so if something like that were to happen that would be very disruptive, Matt Haney, the scientist-in-charge of the AVO at the US Geological Survey, told LiveScience.
‘A large ash cloud might also affect flights that traverse Alaska on their way between North America and Asia,’ he added.
Haney and his colleagues at AVO have been keeping a close eye on Mount Spurr’s recently elevated seismic activity.
He told LiveScience that the earthquakes indicate a 50-50 chance that this type of eruption could happen again.
Since the seismic activity first began in April 2024, the rate of earthquakes has increased from an average of 30 per week to an average of 125 per week, ramping up in early October
The last time Mount Spurr erupted in 1992, it covered Anchorage in a quarter-inch of ash, prompting residents to only venture outside wearing masks and forcing the airport to close
While an impending eruption from the volcano’s side vent appears likely, it is also possible that the earthquakes subside without any volcanic activity
‘It’s had a higher-than-normal number of earthquakes for many months,’ he said.
‘But over the past month, that itself increased, and also the location of the earthquakes changed.’
The seismic activity was previously located near the volcano’s peak, but it has since moved about two miles downslope to the Crater Peak side vent — another piece of evidence to suggest an event similar to the 1992 eruption could be imminent.
But it is also possible that the earthquakes subside without any volcanic activity.
This has happened before. In 2004 and 2005, for example, Mount Spurr experienced increased seismic activity but calmed down by 2006 without an eruption ever taking place.
Another possible (but least likely) explanation for the increased seismic activity could be that Mount Spurr is preparing to unleash an eruption from its summit vent.
Such an event would likely be explosive and could produce lava flows, lahars and other hydrologic hazards, according to AVO.
While this is theoretically possible, Mount Spurr has not erupted from its summit crater since historical record keeping began.
What’s more, the fact that the seismic activity migrated from the summit to the Crater Peak side vent is strong evidence to suggest a flank vent eruption is far more likely.
At this time, the two most likely scenarios are that Mount Spurr fails to erupt, or that it erupts from the Crater Peak side vent. AVO experts say both these possibilities are equally likely.
Therefore, Haney and his colleagues will be keeping a close eye on Mount Spurr for any changes in seismic activity that could signal an eruption is imminent.
‘We expect to see additional changes to monitoring data prior to an eruption if one were to occur as magma moves closer to the surface,’ AVO experts wrote in a statement.
‘This would include further increase in the number of earthquakes, onset of sustained seismic tremor, increased gas emissions, changes in surface deformation, and melting of snow and ice.
‘In 1992, such changes occurred about three weeks prior to the first eruption.’
