Abstract:This study constructs a multi-scale spherical wavelet model of regional crustal deformation in the southeastern margin of the Qinghai-Tibet plateau based on the high-precision GNSS monitoring data from 1999 to 2007 and 2011 to 2017, by fully considering the actual non-uniform distribution of GNSS stations. We quantitatively analyze the variations of current crustal deformation and crustal strain rates at different spatial scales before and after the Wenchuan strong earthquake. The results show that the overall crustal movement in the study area has inherited development characteristics before and after the Wenchuan strong earthquake. Obvious gradient zones of speed differences are formed at the Longmenshan, Anninghe, Zemuhe and Xiaojiang faults, and the high strain rates are mainly concentrated in the above main faults and nearby areas; after the Wenchuan strong earthquake, the overall crustal movement velocity of the study area, especially the GNSS velocity value on the northwest side of the Longmenshan fault zone increased significantly, and the Qiangtang, Bayan Har and Sichuan-Yunnan blocks also show a trend of accelerating the migration to southeastward and promoting the south China block; the strain rate fields at different scales reflect the characteristics of strain accumulation in different spatial ranges. The results of the scale factor q=7 in the southeastern margin of the Qinghai-Tibet plateau are reasonable (the reasonable maximum scale factor); when the scale factor q=6, it can better reveal the characteristics of regional overall tectonic activity, that is, it can clearly reveal the significant high values of principal compressive strain, surface compression and maximum shear strain rate at Longmenshan fault zone after the Wenchuan strong earthquake; when the scale factor q=3-7 (the best combined scale factor), the large-scale (overall) and local deformation characteristics of regional crustal movement can be comprehensively revealed. After the Wenchuan earthquake, the main fault zone in the study area, especially the epicenter and its vicinity, has significantly increased seismic activity.
CHEN Bin,QU Wei,ZHANG Qin et al. Current Crustal Deformation and Multi-Scale Strain Rate Field in the Southeastern Margin of the Qinghai-Tibet Plateau[J]. jgg, 2022, 42(10): 1047-1055.