On May 24, 2013, Mw 8.3 earthquake beneath the Sea of Okhotsk, Russia, occurred as a result of normal faulting at the depth of approximately 600 km.
At the latitude of this earthquake, the Pacific and North America plates are converging at the rate of approximately 78 mm/yr in a west-northwest - east-southeast direction, resulting in the subduction of the Pacific plate beneath Eurasia at the Kuril-Kamchatka trench. Note that some authors divide this region into several microplates that together define the relative motions between the larger Pacific, North America and Eurasia plates; these include the Okhotsk and Amur microplates that are respectively part of North America and Eurasia.
The depth and faulting mechanism of the May 24 earthquake indicate that it ruptured a fault deep within the subducting Pacific lithosphere rather than on the shallow thrust interface between the two plates. This deep section of the Pacific slab beneath the Sea of Okhotsk has hosted several large earthquakes in the past - four above M 6 within 200 km of the May 24 event since 1988. These included a M 7.7 earthquake in July 2008, 115 km to the southwest at the depth of 630 km, and a M 7.3 event in November of the same year, 95 km to the southeast at the depth of 490 km. Because of their great depths, none are known to have caused damage.
Intermediate-depth (70-300 km) and deep-focus (depth > 300 km) earthquakes are distinguished from shallow earthquakes (0-70 km) by the nature of their tectonic setting, and are in general less hazardous than their shallow counterparts, though they may be felt at great distances from their epicenters. The Pacific slab in the region of the May 24 2013 earthquake is seismically active to depths of over 650 km.
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