Fig. 9

P-wave velocity perturbations along a plane directly above the upper surface of the subducting Pacific plate [41]. The velocity perturbation (%) scale is shown at the bottom. Red and blue correspond to low and high velocities, respectively. Open circles denote M ≥ 6 earthquakes for the period from 1900 to 2008. White contours represent the slip distribution of the Tohoku-Oki earthquake [3]. A large star denotes the mainshock hypocenter. Smaller stars show hypocenters of the M 7.3 foreshock and M>7 aftershocks that occurred just after the mainshock