ANALYSIS ON LARGESCALE GRAVITY CHANGES RESULTS OF
JAPAN MW9.0 EARTHQUAKE
1)Key Laboratory of Earthquake Geodesy, Institute of Seismology, CEA, Wuhan 430071
2)Wuhan Base of Institute of Crustal Dynamics,CEA,Wuhan 430071
3)School of Geodesy and Geomatics,Wuhan University,Wuhan 430079
Abstract:Gravity changes in the earthquake source area and the surrounding area before and after 1 month, 6 months and 1 year of Japan MW9.0 earthquake on March 11, 2011 were calculated by using GRACE RL05 time variable gravity field models.We find that a plus or minus alternate phenomenon is more obvious within 1 year before the earthquake. By calculating the coseismic gravity changes based on the earthquake dislocation theory and these of upward continuation to the satellite altitude, the results show that the coseismic gravity changes of the earthquake can be clearly detected by the GRACE satellite. Combined with the GMT best double couple focal mechanism, time series gravity changes of four feature points in the surrounding region are analyzed. We find that dynamic change status of surrounding material of the focal region revealed by the two methods are consistent.