Kanto-Chubu Region

a)On April 10, there was an M4.6 event (maximum seismic intensity: 4) in the southwestern part of Ibaragi Prefecture [south Ibaragi]. Also, on April 15, an M3.9 event occurred nearby.
b)On April 12, there was seismic activity of up to M4.1 in the northeastern part of Chiba Prefecture (off the eastern coast of Chiba).
c)On April 14, there was seismic activity including an M3.5 event (maximum seismic intensity: 4) in the sea near Niijima and Kozushima Islands (near Kozushima).
d)On April 21, there was a deep-focus M5.7 event (at a depth of 350 km) in Wakasa Bay.
e)On April 7, there was an M4.1 event (maximum seismic intensity: 4) in the Joetsu region of Niigata Prefecture.

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