ANCHORAGE, Alaska — A notable uptick in seismic activity beneath a volcano close to Alaska’s largest city has captured the attention of geologists this year.
Mount Spurr, situated roughly 80 miles (129 kilometers) northwest of Anchorage, last erupted in 1992, releasing an ash plume that soared nearly 12 miles (19 kilometers) into the atmosphere. This eruption resulted in flight cancellations and residents needing to wear masks. According to the Alaska Volcano Observatory, a subsequent eruption could significantly disrupt life in the city.
In October, the observatory elevated its alert level for Mount Spurr from green to yellow, following a marked rise in seismic events and the detection of ground deformation via satellite imagery. David Fee, a scientist at the observatory, noted that this year there have been approximately 1,500 minor earthquakes recorded beneath the volcano, in contrast to the average of about 100 typically observed annually.
Despite the apparent surge in seismic activity, Fee stated that it is “not an enormous amount.” It is uncertain whether this could herald an eruption, as similar seismic activity was recorded between 2004 and 2006 without leading to an eruption.
Fee reassured that there have been no significant indicators suggesting an imminent eruption based on current data. “We’ve observed ongoing low-level unrest for some time, and we are monitoring the situation very closely for any signs of change and their implications,” he remarked.
Researchers are keeping a close watch through seismic stations, global satellite monitoring, and a webcam to identify any developments that could predict an eruption. An increase in earthquakes, ground deformation, the formation of a summit lake, or fumaroles—openings in the surface that release gas and vapors—would indicate that magma is potentially moving closer to the surface.
The last eruption of Mount Spurr occurred in 1992 from the Crater Peak flank vent, about 2 miles (3 kilometers) south of the summit. That eruption deposited approximately a quarter-inch of ash in Anchorage, prompting residents to remain indoors or wear masks when venturing outside, with ash clouds traveling as far as Greenland.
Similar eruptions happened at the same vent in 1953, while the last known eruption from the summit took place over 5,000 years ago.
Volcanic ash is known to be sharp and angular, and it has practical applications as an industrial abrasive. The fine particulate rock poses a danger to jet engines, leading to Anchorage and other nearby airports closing during the 1992 eruption.
The closure of airports can be more disruptive than just an inconvenience, particularly in a state with limited road access. Such shutdowns also affect business operations, particularly as Anchorage’s airport ranks among the busiest cargo hubs in the world, alongside Memphis, Hong Kong, and Shanghai—a status influenced by Alaska’s geographical proximity to Asia.
Mount Spurr is part of the Volcanic Ring of Fire and is one of the 53 active volcanoes in Alaska that have shown activity in the past 250 years.
