Abstract:
Considering the contribution of terrestrial water storage from global land data assimilation system to gravity changes, we use the temporal gravity filed models of GRACE from April 2002 to April 2015 to calculate regional gravity changes in the epicenter of
MW9.0 Japan earthquake and its surrounding regions. Then we present annual accumulated gravity changes, differential gravity changes and co-seismic gravity changes in the
MW9.0 source region and its surrounding regions. Meanwhile empirical orthogonal function method is applied to study the contribution of the earthquake to regional gravity changes. The results show that GRACE is able to reveal the evolution of regional gravity field accompanied with the
MW9.0 earthquake, the gravity changes reached about 2×10
-8 m/s
2 in the studied area three years before the
MW9.0 earthquake. Furthermore, the change in coseismic gravity and post-seismic regional gravity field are significant. The results from empirical orthogonal function method indicate that the coseismic effect with temporal and spatial gravity characteristics are presented in the first mode, which fully demonstrates that the Japan earthquake had significant influence on the regional gravity field.