Earthquake under the Sea of Okhotsk on May 24

On May 24, 2013 at 14:44 (JST), there was a Mw8.3 earthquake at a depth of 609 km under the Sea of Okhotsk. In a wide range of Japan, seismic intensities from 3 to 1 were observed. The focal mechanism (CMT solution by the Japan Meteorological Agency) had a compression axis in a dip direction of the Pacific plate. In addition, at 23:56 on same day, there was also a Mw6.7 earthquake at a depth of 623 km under the Sea of Okhotsk. This event had maximum seismic intensity 1 in Japan.
In the vicinity of these events, the Pacific plate is suducting. Both events occurred within the Pacific plate.
For the seismic activity since January 1963, in the vicinity of the recent event (Area b), there have been a few earthquakes of M6.5 or over and these events had seismic intensity 1 in Japan. It is rare that M8 class earthquake occurred at a deep depth of more than 600 km.

In the Japan Meteorological Agency announcement, the regional name of the earthquake [under the ocean near Sakhalin] was used.

Japan Meteorological Agency
[Evaluation of Seismic Activities for May 2013 (June 11, 2013)]