Crustal Kinematics in Chuan-Dian constrained by combining GPS and gravity observations

The area of Chuan-Dian in central Asia is very active and complex, and its intracontinental deformation is generally interpreted as a result of the India-Eurasia collision accommodated by eastward extrusion of lithospheric blocks of quasi-rigid behavior. To accurately investigate the crustal kinematics in Chuan-Dian, especially fault motions, it requires spatially dense measurements of surface rates covering the whole deforming area. Here, we use a recent 10-year GPS (1992-2001) to study the crustal strain and the results show that the strain rate in northern part of Chuan-Dian area is larger than Southern part and the whole region has a strong maximum shear and compression strain patterns. Combining the gravity measurements to jointly inverse the fault kinematics with a new improved model based on the dislocation theory. And the new tested joint model is better than that taking the scale factor I as a constant from the inversion result of MSE (Mean Square Error). The joint inversion results show that Xianshuihe fault in Ganzi area is a left lateral strike slip and Honghe fault in Dianxi area is mainly right lateral slip. Both of these two fault slips are higher than that derived from geological fault slip, indicating that the current fault movements in Chuan-Dian area are more active in recent 10 years, especially in Ganzi and Dianxi area.