????GRACE??????????????????????????????????仯

????GRACE?????????????????P3M6?????????????350 km?????????????????????????2004?????????Mw9.3????????????????????????????????????????????????仯??4.6 μGal??????????????仯?????-8.3 μGal???y????????λ????????????????????????????н????????????7 a????????????仯????5.6 μGal?????????仯???|?????????????????仯???0.6 μGal????????仯????11%????????????????????????????????????????????????????????????????????????Ч??????????Σ???????????????仯|???????????????????????????????????????????????????????????μ??????仯????С??

The Evolution Process of the Gravitational Field after the Sumatra Mw9.3 Earthquake from GRACE RL05 Data

Based on the GRACE data, we successfully extract the co-seismic and post-seismic gravity changes caused by the 2004 Sumatra Mw9.3 earthquake, using P3M6 de-correlation filtering, Gaussian smoothing with a 350 km radius, as well as the difference method. The peak co-seismic gravity changes in the uplift and subduction zones reach up to 4.6 and -8.3 μGal, respectively. Such results agree well in both magnitude and distribution with those calculated by the dislocation theory for a spherical earth model. The total post-seismic gravity changes of 7 years are up to 5.6 μGal in the uplift zone, which is bigger than the corresponding co-seismic gravity changes. On the other hand, the changes in the subduction zone are only 0.6 μGal, just about 11% of corresponding co-seismic gravity changes. Our results imply that the viscosity of the marine strata in the uplift zone is relatively lower than in the strata of the subduction zone. It is the low viscosity in marine area that caused the continuous deformation and relatively bigger gravity changes after the earthquake. The little post-seismic gravity changes in the subduction zone imply the high viscosity of the continental strata.