Kanto-Chubu Region

a) There was clustered seismic activity in the Chuetsu district of Niigata Pref., including an M4.3 earthquake (maximum intensity: 4) on 19 March and an M4.0 event (maximum intensity: 3) on 25 March.
b) An M4.0 shallow earthquake (maximum intensity: 3) occurred on 24 March on the border of Fukui and Gifu Prefs. [Reihoku district of Fukui Pref.].
Furthermore, although they are outside of our time frame, there was an M4.1 earthquake (maximum intensity: 4) on 7 April in the Joetsu district of Niigata Pref. and an M4.6 event (maximum intensity: 4) on 10 April in southern Ibaraki Pref.

Note: Within square brackets ([ ]) is the epicenter place name used by the Meteorological Agency in its information releases.

Note:
M=magnitude
N: total number of events in the figure
depth=depth of hypocenter
UND=Earthquakes of less than M1.0 and earthquakes whose magnitude was not recorded.
The key to the symbols shows on the left the size of an earthquake and on the right the depth of the hypocenter.

Japan Meteorological Agency,Science and Technology Agency

Seismic Activity in Japan March 2000