Present Tectonic Motion Feature of Shanxi Graben Based on the GPS Monitoring Data

In order to visualize the detail motion among stations within the Shanxi graben,we build the No-Net-Rotation based on the GPS repeat observations from 1999 to 2007 of the crustal motion observation network in China.Then the spatial distribution feature of strain fields are analyzed by graphic element method,and the dynamic mechanism of crustal deformation is also deeply analyzed.The results show that present tectonic strain fields of Shanxi graben present tensile strain with NNW-SSE direction,which has good consistency with the earthquake focal mechanisms and regional long-term tectonic deformation background.And the present crustal movement of Linfen and Datong basin is strong,meanwhile,the Linfen and Datong basin is also the areas with high shear strain.In the end the reason of exceptive deformation area is discussed.Then we put forward a significant tectonic event that the crustal activities of tectonic uplift between the Linfen and Taiyuan basin is fierce,and the tectonic uplift is now undergo intense tension rupture.