Earthquake Off-shore of Tokachi on June 5

Earthquake Off-shore of Tokachi on June 5

On June 5, 2009 at 12:30 (JST), there was a M6.4 earthquake at a depth of 31km, off-shore of Tokachi (maximum seismic intensity 4). The focal mechanism showed a reverse fault with a compression axis in a WNW-ESE direction. This event occurred at the boundary between the Pacific and the continental plates.
This event occurred within the aftershock region of the 2003 Off-shore Tokachi Earthquake. Its largest aftershock (M7.1, maximum seismic intensity 6 Lower) occurred in this vicinity on September 26, 2003, and there also was a M6.2 earthquake on February 17, 2007 (maximum seismic intensity 4).
Great ocean-trench earthquakes have repeatedly occurred off-shore of Tokachi in the past. The 1952 Off-shore Tokachi Earthquake (M8.2, maximum seismic intensity 5) caused damage with 33 people killed or missing (Comprehensive Bibliography of Destructive Earthquakes in Japan, Latest Edition). The 2003 Off-shore Tokachi Earthquake also caused damage with 2 people killed or missing (Fire and Disaster Management Agency).

Japan Meteorological Agency
[Seismic Activity for May 2009 (June 11, 2009)]