M 7.4 - east of the Kuril Islands

Tectonic Summary

The January 15, 2009, M 7.4 earthquake east of the Kuril Islands occurred as a result of shallow reverse faulting within the Pacific plate near the outer rise region about 30 km to the east of where the Pacific plate subducts beneath the Okhotsk microplate. The Okhotsk microplate is itself part of the larger North America plate. Focal mechanism solutions indicate that rupture occurred on either a north-northeast- or southwest-striking, moderately dipping reverse fault. Slip on a fault aligned with either nodal plane of the focal mechanism solution is consistent with this intraplate setting. In this region, the Pacific plate moves northwest with respect to the Okhotsk plate at a velocity of about 90 mm/yr.

Large and great earthquakes are common in this region. The location of this event is approximately 90 km to the northeast of the M 8.1 outer rise earthquake of January 13, 2007, which occurred as a result of normal faulting near the Pacific plate outer rise. On November 15, 2006, a M 8.3 subduction-related thrust earthquake occurred approximately 160 km to the southwest.

Hayes et al. (2016) Tectonic summaries of magnitude 7 and greater earthquakes from 2000 to 2015, USGS Open-File Report 2016-1192. (5.2 MB PDF)