Abstract: The process of earthquake incubation is accompanied by tectonic movement,material migration and density changes, which will cause changes in the Earth’s gravity field. The mobile gravity observation may capture precursor information related to earthquake incubation, thereby providing important basis for mid- and short-term earthquake prediction. Based on the mobile gravity observation data in Yunnan, the dynamic variation and evolution of regional gravity field before the Jinggu earthquake of M_S6.6 on October 7, 2014 are studied. The Bouguer gravity anomaly and the dynamic variation of regional gravity field are decomposed by using the wavelet multi-scale decomposition technology, and the crustal medium with different depth field source characteristics is separated by selecting the appropriate wavelet basis. The results show that the wavelet multi-scale results of EGM2008 Bouguer gravity anomaly data are relatively consistent with the measured gravity data. Through comparative analysis, the Jinggu earthquake occurred at the edge of the negative anomaly of the regional gravity field, near the high gradient belt that gravity changes from negative to positive. The gravity field image based on wavelet multi-scale decomposition can clearly reflect the anomaly caused by the change of deep material density in the epicenter area during the preparation and occurrence of Jinggu M6.6 earthquake, which has certain reference research value for the study of tectonic movement and seismogenic mechanism.

Key words: 2014 Jinggu M6.6 earthquake, Gravity anomaly, Wavelet multiscale decomposition