Alaska earthquake Aleutian Islands U.S. Geological Survey tsunami
Earthquake in Alaska (steadyrain/flickr)

7.9 Magnitude Earthquake in Alaska

Depth of quake may have prevented tsunami

Alaska earthquake Aleutian Islands U.S. Geological Survey tsunami

Yesterday afternoon, a magnitude 7.9 earthquake struck in the vicinity of Little Sitkin Island in the western part of Alaska’s Aleutian Islands chain. The earthquake occurred at 12:53 p.m. Alaska Daylight Time (4:53 p.m. EST).

According to the U.S. Geological Survey, the earthquake occurred at a depth of 66.8 miles, or 107.5 kilometers, which is significantly deeper than previous earthquakes in the region, including an M7.9 earthquake in 1996 and an M8.7 earthquake in 1965. 

The main jolt was followed by 21 aftershocks, the largest of which recorded magnitudes of 6.0 and 5.8, respectively.

The National Tsunami Warning Center issued a tsunami warning for portions of the Aleutians stretching from Nikolski to Attu. “Widespread dangerous coastal flooding accompanied by powerful currents are possible and may continue for hours after tsunami arrival,” read the NTWC bulletin. 

In Adak, Alaska, residents evacuated the town and gathered on a nearby elevation where the town’s primary evacuation center is located. “We’re seeing water leave our bay, so we do have everybody up on the Bering Hill area, where our primary evacuation center is at,” City Manager Layton Lockett told the Associated Press.

The tsunami advisory has since been downgraded, with only several-inch-high waves hitting coastal communities. The depth of the earthquake likely mitigated the risk of the dangerous coastal flooding that has occurred after such events in the past.

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From Outside Magazine, April/May 2021
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Lead Photo: steadyrain/flickr