Earthquake Offshore West of Hokkaido on January 12

On January 12, 2021 at 11:39 (JST), there was an M6.0 earthquake (maximum seismic intensity 2) at a depth of 235 km, offshore west of Hokkaido. The focal mechanism (CMT solution) had a tension axis in an NNE-SSW direction. This event occurred within the Pacific plate.
For the seismic activity since October 1997, in the vicinity of the recent event (Area b), the recent event is the first earthquake of M6.0 or over.
For the seismic activity since 1919, in the region around the recent event (Area c), there have sometimes been earthquakes of M6.0 or over. On August 2, 1940, there occurred an earthquake offshore west of Hokkaido (M7.5, maximum seismic intensity 4), which caused tsunami observed on the Japan Sea coasts, such as the tsunami of 83 cm height (maximum height from mean sea level) at Iwanai Port. This tsunami caused damage with 10 fatalities including those at the estuary of the Teshio River, 20 lost houses, 644 spilled ships and so on (Materials for Comprehensive List of Destructive Earthquakes in Japan). Note that this 1940 earthquake occurred at shallower depth than the recent event.

Japan Meteorological Agency
[Evaluation of Seismic Activities for January 2021 (February 9, 2021)]