Gravity Anomalies and Fault Distribution in Sichuan-Yunnan Region
To improve earthquake early warning capabilities and provide scientific basis guidance for disaster reduction in Sichuan-Yunnan region,the satellite gravity was used to study the large-scale gravity anomaly characteristics,seismic faults and seismic source mechanisms.In this paper,the seismic fault property and seismic source mechanism in Sichuan-Yunnan region were revealed by finely processing the satellite gravity data.The research results of Bouguer gravity anomaly show that the gravity anomaly ranges of the Longmenshan Fault Zone,the Xianshuihe Fault Zone,the Zemuhe Fault Zone,and the Anninghe Fault Zone are-50～200mGal,-350～-500mGal,-200～50mGal,and-300～-50mGal respectively.The Longmenshan Fault Zone is moving northwestward,and the trending of the Anninghe Fault Zone and Zemuhe Fault Zone is east-west and north-west respectively.The research results by different analytical methods show that the Huck method can clarify the boundary of the block,while the Rosenbach method can better describe the spatial distribution of the fault.The gravity anomaly changes of four fault zones are derived by the Y-shaped intersection formed by the compression of the blocks.As the results show:(1)The Bouguer gravity values could better reflect the gravity anomaly characteristics of different blocks in the study area;(2)The residual gravity anomaly obtained by the fourth-order trend analysis in Sichuan-Yunnan region can better reflect the abnormal morphology of the geological bodies in the study area;(3)The gravity gradient anomaly zone of the Longmenshan Fault Zone,the Anninghe Fault Zone,the Zemuhe Fault Zone and the Xianshuihe Fault Zone is caused by the compression of high-density materials of Songpan-Ganzi block and crust to the southeast and northeast directions.
万方数据
维普
