Abstract:Based on the EGM2008 global gravity field model, the horizontal and vertical distributions of gravitational field at different scales in the Cangwu earthquake region and south China block are studied. The density variation of deep material and its possible dynamic implication is discussed, providing a deep basis for studying the environment of earthquake inoculation in this region. The lateral variation of gravity anomaly in the Yangtze craton is relatively small, suggesting relatively stable characteristics of craton structure. The upper mantle of the Huaxia block has a gravity positive anomaly, consistent with the subduction angle of the western Pacific plate and the negative gravity anomaly in interphase distribution. Also, the distribution of the high and low density body may be related to lithosphere disintegration and the upwelling of the asthenosphere under the subduction of the western Pacific plate since the Mesozoic. The transition zone between the Yangtze craton and the Huaxia block shows a significant gravity anomaly with high gradient and east-west difference, revealing the complexity of tectonic deformation and transitional zone in deep regions. The lateral complexity and heterogeneity of the multi-scale lattice gravity anomalies, as well as the gravity anomaly in different depths of the crust and upper mantle, reflect the dynamic process of the difference movement between the shallow material structure and the dynamic imbalance in the study area, which may be the deep dynamic environment of the strong earthquake occurring in the study area. The Cangwu earthquake and most strong earthquakes in the study area are located in the transitional zone of gravitational positive and negative anomaly, which is closely related to the perturbation and inhomogeneity density of the deep material distribution.
CHEN Zhaohui,LIU Jinzhao,ZHANG Shuangxi et al. Multiscale Gravity Field Analysis and Dynamic Significance of Seismogenic Environment in Cangwu MS5.4 Earthquake, China[J]. jgg, 2020, 40(2): 175-181.