Seismic activity in the Chuetsu region of Niigata Pref.

An M4.3 shallow earthquake occurred on 19 March at a depth of 14km within the crust; its mechanism was the reverse fault type showing a NW-SE compression axis.
Also, an M4.0 shallow earthquake occurred on 25 March at a depth of 14 km within the crust, some 15km west of the 19 March event. The mechanism was the reverse fault type showing an ENE-WSW compression axis.

Japan Meteorological Agency

Seismic Activity in Japan March 2000