M7.7 - 158km ENE of Poronaysk, Russia 2012-08-14 02:59:42 UTC
Looks like north of Japan and sw of the Aleutians....
No one out there.
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The August 13, 2012 M 7.7 earthquake near Poronaysk, Russia occurred as a result of oblique-reverse faulting deep within the subducting Pacific plate beneath the Sea of Okhotsk, offshore of northeast Russia. The earthquake ruptured a fault in the interior of the inclined subduction zone that dips to the west-northwest beneath the Kuril Islands and Kamchatka, having begun its decent into the mantle at the Kuril-Kamchatka trench. The event resulted from stresses generated by the slow distortion of the subducting plate as it descends through the mantle, rather than on the thrust interface the constitutes the boundary between the Pacific and overlying North America plates; the latter is active only near the Earth's surface, while the subducting Pacific plate is active to depths of over 650 km in this region.
At the latitude of the August 13 earthquake, the Pacific plate moves approximately 81 mm/yr towards the west-northwest with respect to the North America plate. The plate boundary here is sometimes divided into several microplates that together define the relative motions between the larger Pacific, North America and Eurasia plates, including the Okhotsk and Amur microplates that are respectively part of North America and Eurasia. Deep earthquakes in this region of the Pacific plate are not uncommon; there have been 10 similar events deeper than 450 km over the past 40 years, within 300 km of the August 13 2012 earthquake. The largest was a M 7.3 event in November of 2003, approximately 230 km to the south-southeast.
Earthquakes that have focal depths greater than 300 km are commonly termed "deep-focus" earthquakes. Deep-focus earthquakes cause less damage on the ground surface above their foci than is the case with similar magnitude shallow-focus earthquakes, but large deep-focus earthquakes may be felt at great distance from their epicenters. The largest recorded deep-focus earthquake had a magnitude of 8.2, and occurred deep beneath Bolivia in 1994.
The arc extends about 2,100 km from Hokkaido, Japan, along the Kuril Islands and the Pacific coast of the Kamchatka, Russia, peninsula to its intersection with the Aleutian arc near the Commander Islands, Russia. It marks the region where the Pacific plate subducts into the mantle beneath the Okhotsk microplate, a part of the larger North America plate. This subduction is responsible for the generation of the Kuril Islands chain and the deep offshore Kuril-Kamchatka trench. Relative to a fixed North America plate, the Pacific plate is moving northwest at a rate that decreases from 83 mm per year at the arc's southern end to 75 mm per year near its northern edge.
Subduction zones such as the Kuril-Kamchatka arc are geologically complex and produce numerous earthquakes from multiple sources. Deformation of the overriding North America plate generates shallow crustal earthquakes, whereas slip at the interface of the plates generates interplate earthquakes that extend from near the base of the trench to depths of 40 to 60 km. At greater depths, Kuril-Kamchatka arc earthquakes occur within the subducting Pacific plate and can reach depths of nearly 700 km. Since 1900, eight great earthquakes (M8.3 or larger) have occurred along the Kuril-Kamchatka arc. They are the M8.4 1923 Kamchatka earthquake, the M8.6 1933 Sanriku-oki, Japan earthquake, the M9.0 1952 Kuril Island earthquake, the M8.4 1958 Kuril Island earthquake, the M8.5 1963 Kuril Island earthquake, the M8.4 1994 Kuril Island earthquake, the M8.3 2003 Hokkiado, Japan earthquake, and the M8.3 2006 Kuril Island earthquake.