Investigation on Preparation Process of the 2011off the Pacific Coast of Tohoku Earthquake (Mw 9.0) By GPS Data

Abstract:

The dense continuous GPS Earth Observation Network of Japan (GEONET) of the Geospatial Information Authority of Japan (GSI) has been in practice since 1994. So far, the GEONET data have been widely used for precisely detecting co- and post-seismic deformations. In this paper, we have investigated the long-term surface motion prior to the 2011 off the Pacific coast of Tohoku earthquake (Mw 9.0). Long-term linear trends of precise daily coordinates of GEONET stations have been analyzed and clear changes of the deformation rate starting from about 1.4 year before the mega event have been detected. These changes of the surface deformation rate suggest those of stress accumulation. The spatial distributions of deformation rate have shown westward directional changes in a large area along the Pacific coast prior to the mega event.