Abstract:Based on the dense GNSS data from the multi-source projects, we calculate the high spatial resolution GNSS horizontal velocity field and strain rate field of the study area. Using seismic waveform data, the focal mechanism solution is solved by CAP method. On this basis, the damping regional stress inversion method is used to obtain the spatial distribution characteristics of the regional tectonic stress field in Sichuan-Yunnan block. Combined with the seismic activity characteristics of major faults, the crustal deformation characteristics in Sichuan-Yunnan region are comprehensively analyzed. The results show that: 1) The maximum principal compressive stress of the shallow part of the block and the maximum principal compressive strain rate of the surface change from SSE to near SN,which present good consistency. The deformation depth inferred from GNSS data can extend to at least 20 km. 2) The cause of eastward sliding and clockwise rotation of the Sichuan-Yunnan block are the pushing/thrust effect caused by the Tibet Plateau, the obstruction effect caused by the South China block, and the right-lateral shear dragging effect caused by northward movement decreases from west to east between the Indian plate and the Eurasian plate. 3) Under the effects of the clockwise rotation and the absorption and conversion of the strike-slip thrust fault zone caused by the comprehensive couple forces, the SE extrusion of material in the Tibet Plateau is limited.
ZHUANG Wenquan,LI Jun,HAO Ming et al. Study on the Characteristics of Current Crustal Activity in the Southern Sichuan-Yunnan Block Using Dense GNSS Data and Focal Mechanism Solution[J]. jgg, 2021, 41(7): 732-738.