Sunday, 13 March 2022

Magnitude 5.1 Earthquake beneath Kenai Peninsula Borough, Alaska.

The Alaska Earthquake Centre recorded a Magnitude 5.1 Earthquake at a depth of 95.6 km, about 42 km to the west of Nikiski in Kenai Peninsula Borough, Alaska, slightly before 11.00 am Alaskan Standard Time (slightly before 8.00 pm GMT) on Saturday 12 March 2022. There are no reports of any damage or casualties associated with this event, but people have reported feeling it over a wide area of south-central Alaska.

The approximate location of the 12 March 2022 Alaska Earthquake. USGS.

Alaska lies on the North American Plate, with the Pacific Plate underlying the ocean to the south. The Aleutian Trench runs along much of the south coast of Alaska, with the Pacific Plate being subducted beneath this and passing under Alaska as it sinks into the Earth. Off the coast of southeast Alaska the Pacific and North American Plates pass one-another horizontally, with the Pacific Plate moving northward and the North American to the south (a transform plate margin). This is not a smooth process, and the plates frequently stick together, then break apart as the pressure builds up, causing Earthquakes.

How the subduction of the Pacific Plate beneath the North American Plate fuels the volcanoes of Alaska. Alaska Volcano Observatory.

Witness accounts of quakes can help geologists to understand these events and the rock structures that cause them. If you felt this quake (or if you were in the area but did not, which is also useful information) you can report it to the United States Geological Survey here.

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