CRUSTAL DEFORMATION CHARACTERISTICS AFTER Ms8.0
WENCHUAN EARTHQUAKE IN SICHUAN-YUNNAN REGION
1）Key Laboratory of Earthquake Geodesy, Institute of Seismology, CEA, Wuhan 430071
2）First Crust Monitoring and Application Center, CEA, Tianjin 300180
3）No.2 Engineering Corporation Limited of CR20G, Beijing 100000
Abstract The velocity field of the 296 stations in the SichuanYunnan region has been obtained with the GPS observation data of the CMONOC from 2009 to 2011. Based on the continuous deformation hypothesis, we use the data of the horizontal velocity field to compute the distribution of horizontal strain field in this region by the triangle method. Preliminary analysis indicates that: 1） In SichuanYunnan region, the crustal movement of north and west is stronger than that of south and east. The SichuanYunnan rhombic block is characterized by clockwise rotation. 2） The directions of the principal compressive strain axis and the P axis of the focal mechanism solution show that tectonic stress field in this region is relatively stable in a long term. 3） The high value areas of the principal strain and the maximum shear strain rate are in the Longmenshan fault zone and its surrounding region. In addition to the above areas, the significant highvalue properties of the maximum shear strain rate can be seen in the south of the Xianshuihe fault zone and the northwest segment of the Red River fault zone.
