Earthquake in the Shimokita Region, Aomori Prefecture on April 23

On April 23, 2015 at 22:15 (JST), there was a M3.8 earthquake (maximum seismic intensity 4) at a depth of 7 km in the Shimokita region, Aomori prefecture. This event occurred within the crust. After this event any aftershock with seismic intensity 1 or over has not occurred.
For the seismic activity since October 1997, in the vicinity of the recent event (Area a), there was an earthquake of M3.0 or over.
For the seismic activity since January 1923, in the region around the recent event, there was a M5.1 earthquakes on April 25, 1972.

Japan Meteorological Agency
[Evaluation of Seismic Activities for April 2015 (May 14, 2015)]