Earthquake Offshore of Fukushima Prefecture on November 6

On November 6, 2023 at 02:10 (JST), there was an M5.0 earthquake (maximum seismic intensity 4) at a depth of 56 km, offshore of Fukushima prefecture. This event occurred within the Pacific plate. The focal mechanism (CMT solution) showed a reverse fault type with a compression axis in an NNW-SSE direction. In the vicinity of the recent event (Area b), On March 16, 2022, there was an M7.4 earthquake (maximum seismic intensity 6 Upper) and the seismic activity became high. The seismic activity after March 16, 2022 has become lower than the initial stage, still the state of rather high activity continues.
For the seismic activity since October 1997, in the vicinity of the recent event (Area b), before "the 2011 off the Pacific coast of Tohoku Earthquake" (hereinafter called as "the Tohoku-Oki Earthquake"), there had been no earthquakes of M5.0 or over. After "the Tohoku-Oki Earthquake," the number of earthquakes increased and there have sometimes been earthquakes of M5.0 or over.

For the seismic activity since 1919, in the area around the recent event (Area c), before the occurrence of "the Tohoku-Oki Earthquake" there had often been earthquakes of M7.0 or over. On November 5, 1938 at 17:43 (JST), there was a M7.5 earthquake (maximum seismic intensity 5), which caused tsunami with a height of 113 cm (peak to trough amplitude) at Hanabuchi, Miyagi prefecture.

Japan Meteorological Agency
[Evaluation of Seismic Activities for October 2023 (November 10, 2023)]