青藏高原东南缘现今地壳形变与多尺度应变率场特征

利用青藏高原东南缘1999~2007年与2011~2017年高精度GNSS监测资料，充分顾及GNSS测站非均匀分布的特性，构建青藏高原东南缘地壳形变多尺度球面小波模型，定量分析汶川强震前后该区域地壳形变与不同空间尺度下地壳应变率场变化特征。研究结果表明，汶川强震前后研究区整体地壳运动具有一定继承性发展特征，均在龙门山、安宁河、则木河与小江断裂处形成明显的速度差异梯度带，且高应变率值也主要聚集在上述主干断裂及附近区域；汶川强震后，研究区域整体地壳运动速率量值，特别是龙门山断裂带西北侧地壳运动速度量值显著增大，羌塘、巴颜喀拉与川滇地块也呈现出加速向南东运移并推动华南块体的趋势。不同尺度下的应变率场反映出不同空间范围下区域应变积累特征，青藏高原东南缘区域在尺度因子q=7时的计算结果是合理的（合理的最大尺度因子）；当尺度因子q=6时，能较好地揭示出区域整体构造活动特性，即清晰地揭示出汶川强震后龙门山断裂处呈现出的显著主压应变、面压缩与最大剪应变率高值特征；当尺度因子q=3~7时（最佳组合尺度因子），可较好地综合揭示出区域地壳大尺度（整体）形变与局部形变特征。汶川强震后，研究区域主干断裂带，特别是震中及其附近区域地震活动性显著增强。

Current Crustal Deformation and Multi-Scale Strain Rate Field in the Southeastern Margin of the Qinghai-Tibet Plateau

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.