Magnitude 6.7 OFF THE COAST OF NORTHERN CALIFORNIA
Friday, June 17, 2005 at 06:21:42 UTC
Preliminary Earthquake Report
U.S. Geological Survey, National Earthquake Information Center
World Data Center for Seismology, Denver
Preliminary analysis of the aftershock indicates that it resulted from slip on a NE striking, left-lateral, strike-slip fault; this type of mechanism has been documented for other earthquakes having locations in the interior of the Gorda plate.
Earthquakes are common in the Gorda plate, which is subjected to north-south compression due to the north-west moving Pacific Plate that collides with the southern boundary of the Gorda Plate along the east-west Mendocino Fracture Zone. In addition to the June 15th mainshock, there have been 4 other quakes of magnitude M>6 that have occurred with 50 miles radius of the epicenter of this quake (November 8 1980, August 16 and 17 1991, and July 24 1996).