Poster of the Offshore Eastern Japan Earthquake of 07 December 2012 - Magnitude 7.3

Tectonic Summary

The December 7, 2012 M 7.3 earthquake east of Sendai, Japan, occurred as a result of reverse faulting within the oceanic lithosphere of the Pacific plate, approximately 20 km east of the plate boundary between the Pacific and North America plates that marks the location where the Pacific subducts beneath Japan. At the epicenter of this earthquake, the Pacific plate moves west-northwestard with respect to the North America plate at a velocity of approximately 83 mm/yr. 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 plate boundary region surrounding the December 7, 2012 earthquake hosts moderate to large earthquakes fairly regularly - 12 events of M7 or larger have occurred within 250 km of this earthquake over the past 40 years. These historic events include the M9.0 Tohoku earthquake of March 11, 2011, which ruptured a large portion of the subduction zone plate interface to the west of the December 7th event, and which spawned a major tsunami that caused significant devastation along the Honshu coast. A series of aftershocks of that 2011 megathrust event also occurred to the east of the plate boundary within the Pacific plate, including a M 7.6 normal faulting earthquake 60 km to the northeast of the December 7 2012 event.

Earthquake Report

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