Distribution of GPS stations of GEONET used for determining the slip distribution of the fault. The observed displacements (solid arrow) are compared with the displacements calculated (open arrows) for the slip distribution with the center of slip close to the trench (Fig. 1(b)). The observed displacements at the ocean-bottom observation sites (Sato et al., 2011) are also shown together with the calculated ones. The gray arrows are the displacements calculated for the slip distribution with the center of slip distant from the trench (Fig. 1(a)). Large and small stars indicate the epicenters of the Mw 9.0 Tohoku-Oki earthquake and the Mw 7.3 foreshock, respectively. The cross denotes the ocean-bottom observation site near the trench where an extremely large displacement is observed (Ito et al., 2011).