ANCHORAGE, Alaska — A rise within the variety of earthquakes beneath a volcano close to Alaska’s largest metropolis this 12 months has geologists paying consideration.
Mount Spurr, about 80 miles (129 kilometers) northwest of Anchorage, final erupted in 1992, spewing an ash cloud almost 12 miles (19 kilometers) into the air, prompting flights to be canceled and folks to don masks. One other eruption on the 11,100-foot (3,383-meter) stratovolcano may very well be severely disruptive to town, in accordance with the Alaska Volcano Observatory.
The observatory raised its alert standing for Mount Spurr in October — from inexperienced to yellow — when the rise in seismic exercise grew to become pronounced and a floor deformation was noticed in satellite tv for pc knowledge. Observatory scientist David Charge mentioned Friday there have been about 1,500 small earthquake under the volcano this 12 months, in comparison with about 100 in a traditional 12 months.
Whereas which may look like so much, it’s “not an enormous amount,” Charge mentioned. It may very well be a precursor to an eruption — or not. Related seismic unrest occurred from 2004 to 2006 earlier than subsiding with out an eruption.
“We don’t see any significant change in our data that would tell us that an eruption is imminent,” Charge mentioned. “Things have been kind of this low-level unrest for a while now and we’re, of course, watching it very closely to detect any changes and what that might mean.”
Scientists are monitoring seismic stations, world satellite tv for pc knowledge and a webcam for extra modifications that might sign an impending eruption. If magma is transferring nearer to the floor, there can be a rise in earthquakes, floor deformations, the creation of a summit lake or fumaroles, that are vents that open within the floor to vent gasoline and vapors.
The volcano final erupted in 1992 from the Crater Peak flank vent, positioned about 2 miles (3 kilometers) south of the summit. The eruption dropped a few quarter-inch of ash in Anchorage that 12 months, prompting residents to remain inside or to exit donning masks, and the cloud drifted so far as Greenland.
The same eruption from the identical vent occurred in 1953. The final recognized eruption from the summit was greater than 5,000 years in the past.
Volcanic ash is angular and sharp and has been used as an industrial abrasive. The powdered rock could cause a jet engine to close down, which prompted Anchorage and different close by airports to shut through the 1992 eruption.
Closing airports is all the time an inconvenience in a state with few roads, however may be extra than simply inconvenient. Enterprise would even be impacted for the reason that Anchorage airport at the moment is among the many world’s busiest cargo hubs with Memphis, Hong Kong and Shanghai, primarily due to Alaska’s proximity to Asia.
Mount Spurr, positioned on the Volcanic Ring of Hearth, is one in every of 53 volcanoes in Alaska which have been lively inside the final 250 years.