GPSM onitoring ofX ianshuihe Fault and Blocks on Its Both Sides

Based on the GPS measurement of the Xianshuihe fault and blocks on its both sides, Chuan-Dian block and Chuan-Qing block, a velocity field on the Eurasia reference frame was obtained. The movement velocities ofGPS stations in the region were estimated using least-squares fitting under the hypotheses of rigidmass. The fitting result shows that themovementvelocities of the Chuan-Dian and Chuan-Qing blocks are 19. 5±3. 4 and 13. 2±3. 4 mm/a respectively, and the Chuan-Qing block moves at a speed of 8. 3±3. 4 mm/a relative to the Chuan-Qing block. The movementvelocity of the Xianshuihe fault is 7. 9 to 8. 8 mm/a( it is 8. 8±3. 5 mm/a in Garzê- Qianning segment and 7. 9±3. 3 mm/a in Qianning-Kangdin segment). The above results show that the region covered the Xianshuihe faul,t the Chuan-Dian and Chuan-Qing blocks is an important tectonic activity zone.