Sunday 13 November 2016

Magnitude 5.2 Earthquake beneath the Alaskan Peninsula.

The United States Geological Survey recorded a Magnitude 5.2 Earthquake at a depth of 11.4 km about 106 km to the northeast of Chignik Lake on the Alaskan Peninsula, slightly after 12.50 pm local time (slightly after 9.50 pm GMT) on Saturday 12 November 2016. There are no reports of any damage or casualties associated with this event, but people have reported feeling it locally.
The approximate location of the 12 November 2016 Alaskan Peninsula Earthquake. Google.
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 the Alaskan Peninisula and te Aleutian Islads, with the Pacific Plate being subducted beneath this and passing under Alaska as it sinks into the Earth. The 4 January quake occurred in the far southeast of the state; east of the extent of the Aleutian Trench. 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.

Subduction of the Pacific Plate beneath the North American Plate fueling earthquakes and volcanism on the Alaskan peninsula. 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 USGS here.
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