Earthquake Offshore East of Hokkaido on June 28
On June 28, 2017 at 21:07 (JST), there was an M5.7 earthquake (maximum seismic intensity 3) at a depth of 65 km (CMT solution), offshore east of Hokkaido. This event occurred within the Pacific plate. The focal mechanism (CMT solution) had a compression axis in a WNW-ESE direction.
For the seismic activity since October 1997, in the vicinity of the recent event (Area a), there have often been earthquakes of M5.0 or over, such as a recent M5.7 earthquake (maximum seismic intensity 3) on May 22, 2017. The largest magnitude one was an M7.0 earthquake (maximum seismic intensity 4) occurring on January 28, 2000, which caused damage with 2 injured persons (Fire and Disaster Management Agency).
For the seismic activity since January 1923, in the area around the recent event (Area b), there have sometimes been earthquakes of M7.0 or over; there were 2 earthquakes of M8.0 or over. On October 4, 1994, there was "the 1994 Hokkaido-Toho-Oki Earthquake" (M8.2, maximum seismic intensity 6), occurring within the Pacific plate, as same as the recent event, which caused tsunami observed at the area extending from Hokkaido to Okinawa prefecture, with height of 168 cm at Hanasaki, Nemuro city. This earthquake caused damage with 436 injured persons and 7,519 collapsed houses and so on (Disaster Records in1994 and 1995 (Hokkaido)).
Japan Meteorological Agency
[Evaluation of Seismic Activities for June 2017 (July 11, 2017)]