M 7.2 - 207 km WSW of Adak, Alaska

  • 2007-12-19 09:30:27 (UTC)
  • 51.360°N 179.509°W
  • 34.0 km depth

Tectonic Summary

The December 19, 2007, M 7.2 Aleutian Island earthquake occurred as the result of shallow thrust faulting on the boundary between the North America plate and the Pacific plate. At the location of the earthquake, the Pacific plate moves to the northwest relative to the North America plate at a velocity of about 72 mm/yr, subducting at the Aleutian Trench. The location, depth, and focal mechanism solutions indicate that the earthquake likely occurred from thrust faulting on the interface between the plates.

The earthquake of December 19, 2007, ruptured a segment of the Pacific/North America plate boundary that is spatially situated between the segments of the plate boundary that ruptured in the great Aleutian Island earthquakes of March 9, 1957 (M 8.6) and February 4, 1965 (M 8.7). Great earthquakes also occurred in the central Aleutian Arc on May 7, 1986 (M 8, about 300 km from the site of the 2007 earthquake) and June 10, 1996 (M 7.9, about 150 km from the site of the 2007 earthquake).

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)

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