The United States Geological Survey recorded a Magnitude 5.5 Earthquake at a depth of 0.9 km in Northwest Arctic Borough, Alaska, slightly before 10.00 pm local time on Friday 2 May 2014 (slightly before 9.00 am on Saturday 3 May, GMT). This is a a fairly large quake, though it happened in a remote area, and there are no reports of any damage or casualties; it was reportedly felt in the settlement of Kotzebue, roughly 100 km south of the epicenter. The quake was followed by a number of aftershocks, but these were all smaller than the initial event.
The approximate location of the 2 April 2014 Northwest Arctic Borough Earthquake. Google Maps.
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. 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.
Witness reports can help geologists to understand the processes going on in Earthquakes. If you felt this quake (or were in the area but did not, which is also useful information) you can report it to the USGS here.
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