Study on Crustal Strain of Wenchuan by Three-Dimensional Space Data
1 Shaanxi Railway Institute, 1 East-Zhanbei Street, Weinan 714000, China
2 College of Geomatics,Xi’an University of Science and Technology, 58 Yanta Road, Xi’an 710054, China
Abstract：The analytic expressions of principal strain and shear strain are deduced by quadrilateral law with three-dimensional deformation data. The horizontal and vertical strains of Wenchuan are calculated with the three-dimensional GPS data during 2005 to 2008. The results show that the horizontal principal strains of Wenchuan and Yingxiu are extrusion. The main vertical principal strain is positive in the southeast direction, but it is negative in the northwest direction. The main vertical principal strain is consistent with the observation that the surface is sinking in the southeast and uplifting in the northwest. The maximum principal strain is in Y (east) direction. The maximum shear strain is in XY (northeast) direction. Wenchuan is situated on the high gradient of the principal and shear strains, coinciding with the location of the earthquake
