Hokkaido Region

a)On April 26, an M5.0 event occurred in the Chishima Archipelago.
b)In the area of Mt. Usuzan (Iburi Administrative District), seismic activity related to the volcanic activity occurred, including an M4.6 event (maximum seismic intensity: 5 lower) on April 1.
c)On April 12, an M4.3 event (maximum seismic intensity: 3) occurred in the sea off the Matsumae coast (off the southern coast of Hokkaido) on the edge of an area where activity has been continuing since October 1995.

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 April 2000