Fig. 2.

(a) Map of earthquake hypocenters and (b) depth section along the N-S direction, as determined by the double-difference method. Focal mechanisms of major events are shown in Fig. 2(a), which were determined by HSRI routine analysis. (c) Time-magnitude diagram and cumulative number of the events which occurred in the period from 0:00 on March 1 to 12:00 on April 2, 2011. An arrow shows the occurrence time of the 2011 off the Pacific coast of Tohoku Earthquake. Magnification of the time-magnitude diagram within ±2 h from the main shock occurrence time is shown in the inset map.