wowo, busy tonight. here is a pretty big quake http://earthjay.com/earthquakes/20130523_sea_okhotsk/sea_okhostk_20130523_2300.PNG
the kuril trench has been active (subduction zone where the pacific plate subducts beneath the north america plate) and the yellow and orange dots in my map show recent quakes there. this 8.2 (which may change) seems to be directly down-dip of the swarm. i have placed a red symbol in the approximate epicenter because the data are not yet updated on google earth. the usgs page has an excellent summary map for the region.this large earthquake is pretty deep.
here is the usgs map that shows the historic segmented rupture along that subduction zone. http://earthquake.usgs.gov/earthquakes/tectonic/images/kuril_tsum.pdf (funny, it does not have the 2011 tohoku-oki earthquake)
this region is interesting because to the north, we do not really yet understand how the north america plate connects with the eurasia plate. the mid atlantic ridge passes north through iceland, then goes through the arctic ocean, and is thought to form the boundary between the NAP and the EAP.
here is an update: a post from nature.com