Earthquake in the Northern Nagano Prefecture on November 22
On November 22, 2014 at 22:08 (JST), there was a M6.7 earthquake (maximum seismic intensity 6 Lower, ①) at a depth of 5 km in the northern Nagano prefecture. This event caused damage with 46 injured persons, 36 totally and 66 seriously collapsed houses (as of December 1 at 13:30, Fire and Disaster Management Agency). This event occurred within the crust. The focal mechanism had a compression axis in a WNW-ESE direction.
After the occurrence of this event, aftershock activity was observed in the region about 20 km in an N-S direction, from Otari Village to Hakuba Village. Aftershocks activity is gradually decreasing. The maximum aftershock is a M4.5 one (maximum seismic intensity 5 Lower, ②) that occurred on the same day at 22:37. There were 113# aftershocks with seismic intensity 1 or over till December 7, such as a M3.6 one (maximum seismic intensity 4, ③) on 24th at 06:12, and a M3.9 one (maximum seismic intensity 4, ④) on 25th at 06:26. The region of these aftershock activity is almost the same as the position of the Kamishiro fault which is a part of Itoigawa-Shizuoka tectonic line active fault system.
# This value is preliminary and subject to change at a later date of survey.
For the seismic activity since October 1997, in the vicinity of the recent event (Area a), there was a M5.0 earthquake (maximum seismic intensity 4) on July 1, 1998.
For the seismic activity since January 1923, in the vicinity of the recent event (Area b), there was a M5.9 earthquake (maximum seismic intensity 4) that caused damage with 4 road fissures (Comprehensive Bibliography of Destructive Earthquakes in Japan).
Japan Meteorological Agency
[Evaluation of Earthquake in the Northern Nagano Prefecture on November 22 (December 9, 2014)]