Posted by Chris M Monday, December 29, 2008
As previously shown many times on the geoblogosphere, the USGS's earthquake site is a good site for recent and occurring earthquakes. While looking through the site I saw on November 24, 2008 at 09:02 UTC, a 7.3 magnitude quake happened in the Sea of Okhotsk, off the west coast of Kamchatka. Under the "seismic cross section" there is a great map illustrating the variation in quake depth at subduction zones. The November 24 quake was deep focus at a depth of 491 km, well into the Wadati-Benioff zone. The map shows the increasing depth of foci from the boundary, as the subducting plate moves deeper into the mantle.
Seismic Cross Section for Magnitude 7.3 Sea of Okhotsk at
Monday, November 24, 2008 at 09:02:58 UTC. Preliminary Earthquake Report U.S. Geological Survey, National Earthquake Information Center World Data Center for Seismology, Denver.