J-EGG500 from the Japan Oceanographic Data Center, GTOPO30 from the US Geological Survey, and ETOPO2v2 from the National Geophysical Data Center in the U.S. were used for the topographic and bathymetric data.
N: total number of events in the figure
Japan Meteorological Agency
Ministry of Education, Culture, Sports, Science and Technology
[Seismic Activity for April 2011 (May 11, 2011)]