Earthquake Off-shore East of the Chishima Islands on March 3
On March 3, 2008, at 18:30 (JST) there was a M6.9 earthquake off-shore east of the Chishima Islands (Moment magnitude from a global CMT analysis is Mw 6.5. No observed intensities equal to or greater than 1 in Japan). The focal mechanism (from a global CMT analysis) showed a reverse fault with a compression axis in a NW-SE direction. It is thought that this event occurred at the boundary between the Pacific and the continental plates.
In this vicinity (on the NW side of the trench axis, Area c), there was a M7.9 earthquake on November 15, 2006. In addition, on the SE side of the trench axis, there was a M8.2 event on January 13, 2007.
The focal mechanisms (from global CMT analyses) since September 2006 show that reverse faults are distributed on the NW side and normal faults are seen on the SE side of the Chishima-Kamchatka Trench. The recent event is located in the southern part of the area on the NW side of the trench where many reverse faults are seen.
Japan Meteorological Agency
[Seismic Activity for March 2008 (April 11, 2008)]