Hokkaido Region

a) An M5.3 earthquake occurred on 30 March east offshore of Hokkaido [Southeast Offshore of Nemuro Peninsula]. This earthquake was situated northwest of the M6.8 event of 28 January and within the aftershock area of the 1994 East Offshore of Hokkaido Earthquake.
b) Seismic activity in the vicinity of Mt. Usuzan (western part of Tanburi Administrative District) beginning on 27 March and including a maximum M4.3 earthquake (maximum intensity: 5 lower) on 30 March was related to the volcanic activity of Mt. Usuzan.

Moreover, although it is outside our time frame, an M4.6 earthquake (maximum intensity: 5 lower) occurred on 1 April as part of the activity in the vicinity of Mt. Usuzan. Eruption of Mt. Usuzan began on 31 March.
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