Two earthquakes shook northwest Alaska last week. A magnitude 5.1 earthquake on March 13, around 50 miles north of Ambler, was the largest in the state that week. And the day before, a magnitude 5 struck near Point Hope.
Researchers say that's unusual. In the “seismically quiet” northern regions of Alaska, earthquakes of this magnitude typically occur, on average, 2-3 years apart.
A pair of magnitude 4 quakes were also recorded the same week, in Teller and Kaktovik.
“They were all in locations with no mapped faults, but they each have a history of modest-sized earthquakes.” said Elisabeth Nadin, geologist and host of “What’s Shaking Alaska” a podcast produced by the Alaska Earthquake Center.
The quakes are not related, but they follow similar mechanics which are different from earthquakes that occur in the Aleutian or south-central areas in Alaska, Nadin said.
“The type of movement in these areas is typically extensional or lateral,” said Nadin. “This has been attributed to the crust ‘relaxing’ in the wake of the compression that formed the Brooks Range.”
“It's kinda like when a bulldozer pushes rocks into a large pile. As the dozer pulls away, the pile collapses outward a bit,” said Dr. Heather McFarlin, data manager for the center.
McFarlin said there have been earthquake swarms in the area, like one that occurred in Noatak a decade ago, but not recently. Last week's quakes are not believed to have occurred from human activity. No damage was reported, but some in Kotzebue reported feeling the earthquake near Point Hope.
There is no reason for the public to be alarmed by the quakes, but McFarlin encouraged residents to be prepared and aware of geologic hazards.
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