Abstract: On August 3 and October 7, 2014, the Ludian M_S6.5 earthquake and Jinggu M_S6.6 earthquakes respectively occurred in Yunnan, China. Based on the EGM2008 gravity field model, this paper studies the Isostatic gravity anomaly and multi-scale Bouguer gravity anomaly of the southeastern Tibetan Plateau. The deep tectonic environment and dynamic process of the Ludian and Jinggu earthquakes are analyzed and recognized, which provide a deep understanding of tectonic movement and earthquake inoculation environment in this region. The Bouguer gravity anomaly and the Isostatic gravity anomaly in the study area are correlated well with the geological structure, and the severe regional Bouguer gravity anomalies and the non-equilibrium state of the Sichuan-Yunnan block are closely related to its strong crustal deformation, fracture and seismic activity. The strong earthquakes in the study area are mainly distributed in the transition zone and high gradient zone of gravity anomaly on both sides of the fault zone, and the significant difference of medium density on both sides of the fault zone is the deep tectonic background of strong earthquakes. The difference of the deep and shallow density structure of Ludian and Jinggu hypocentral region being revealed by Bouguer gravity anomaly and Isostatic gravity anomaly indicates, the seismogenic environment difference between Ludian and Jinggu earthquakes.

Key words: Gravity field, Wavelet multi-scale analysis, Southeastern of Tibetan Plateau, EGM2008, 2014 Ludian M_S6.5 earthquake, 2014 Jinggu M_S6.6 earthquake