Abstract:The long-term gravity changes of the Chile region are obtained by GRACE gravity satellite data. The gravity changes before and after the 2010 MW8.8 Chile earthquake are further analyzed through the time-series of gravity changes of typical points. Finally, the coseismic gravity changes detected by GRACE are compared with the results calculated by the spherical dislocation model. The results show that the strong earthquake caused significant positive and negative gravity changes between the upper wall and foot wall of the seismogenic fault. The time-series of the gravity changes of typical points all clearly reveal the jumping phenomenon caused by the strong earthquake, as well as the abnormal signals caused by the three strong aftershocks. Especially, the gravity changes of a typical point in the epicenter area presents characteristics of "decrease-increase-decrease-increase-earthquake occurrence" from 2007 to 2010 before the strong earthquake. The magnitude and distribution of coseismic gravity changes observed by GRACE are in good agreement with the results calculated by the spherical dislocation model. In the different stages of the earthquake, the gravity changes between the two sides of seismogenic faults are also different. In addition, because of the effect of stratum viscosity after the strong earthquake, the gravity changes around the seismogenic faults will continue to show the trend of positive and negative changes.
QU Wei,AN Dongdong,ZHANG Qin et al. Gravity Variations and Tectonic Activity of the MW8.8 Chile Earthquake Observed by the GRACE[J]. jgg, 2018, 38(6): 551-556.