Seismic Activity for All of Japan in April 2011 (Magnitude 4.0 and greater)



During April, within the aftershock area of the 2011 off the Pacific Coast of Tohoku Earthquake, there were 2 earthquakes of M7.0 or over, 10 earthquakes of M6.0 or over and 56 earthquakes of M5.0 or over. There were 10 earthquakes with a maximum seismic intensity 5 Lower.

Apart from these earthquakes, there were the following activities outside the aftershock area of the 2011 off the Pacific Coast of Tohoku Earthquake.
* On April 1, there was a M5.0 earthquake (maximum seismic intensity 5 Upper) in the northern inland, Akita prefecture.
* On April 12, there was a M5.6 earthquake (maximum seismic intensity 5 Lower) in northern Nagano prefecture. The largest aftershock was a M4.7 earthquake (maximum seismic intensity 3) on the same day.
* On April 16, there was a M5.9 earthquake (maximum seismic intensity 5 Upper) in southern Ibaraki prefecture. Since the 2011 off the Pacific Coast of Tohoku Earthquake, in the vicinity of this event, the seismicity has been brisk and there was a M5.0 earthquake (maximum seismic intensity 5 Lower) on April 2.
* On April 17, there was a M4.9 earthquake (maximum seismic intensity 5 Lower) in the Chuetsu region, Niigata prefectures.
* On April 19, there was a M4.9 earthquake (maximum seismic intensity 5 Lower) in the southern inland, Akita prefecture.

[The events which have date, time and magnitude in the figure are M5.0 or greater earthquakes, or M4.0 or greater earthquakes that have a maximum seismic intensity of 5 Lower, or greater. The above mentioned event(s) fall under one or more of the following categories; M6.0 or greater earthquakes, or M4.0 or greater earthquakes that have maximum seismic intensity of 5 Lower, or greater.]

N: total number of events in the figure

Japan Meteorological Agency
Ministry of Education, Culture, Sports, Science and Technology
(Japan Meteorological Agency data include data from the National Research Institute for Earth Science and Disaster Prevention and related universities.)
[Seismic Activity for April 2011 (May 11, 2011)]