Abstract:The post-seismic deformation characteristics of the MW9.0 Japan earthquake are studied based on GPS observation. The post-seismic horizontal displacements observed by GPS accumulated to 60~165 cm for the east component, and 20~65 cm for the south component, in nearly 5 years following the main shock, until December 2015. For GPS sites further away from the epicenter, the post-seismic displacements have exceeded their co-seismic changes. Moreover, the post-seismic deformation is still continuing. According to the theories of afterslip and viscoelastic dislocation, the post-seismic deformation is simulated and the GPS observations are explained by these two mechanisms. The simulation results indicate that afterslip plays a major role in the initial stage of post-seismic deformation, but it shows an exponential decay with time. On the contrary, the contribution of viscoelastic relaxation increases with time. The results also suggest that post-seismic deformation can be reasonably explained by combining these two mechanisms. In addition, the mantle viscosity in the seismic area is inferred to be of the order of 1.5×1019 Pa·s from post-seismic deformation observed by GPS.
LIANG Ming,WANG Wuxing. Study on the Post-Seismic Deformation Mechanism Caused by the MW9.0 Japan Earthquake Based on the GPS Observation[J]. jgg, 2017, 37(12): 1285-1290.