THE VERTICAL COSEISMIC DEFORMATION FIELD OF THE WENCHUAN EARTHQUAKE BASED ON THE COMBINATION OF GPS AND INSAR

摘要

Vertical coseisimic deformation near seismogenic fault provides meaningful information for understanding of rupture characteristics of the seismogenic fault and focal mechanism. Taking Wenchuan thrust earthquake for an example, we interpolate GPS horizontal observed deformation using Biharmonic spline interpolation and derive them into East-Westward or North-Southward deformation field. We first use reliable GPS observed value to correct InSAR reference point and to unify both GPS and InSAR coordinate frame, and then obtain a continuous vertical deformation field by combined calculation of GPS and InSAR LOS deformation field. The results show that the vertical deformation of both hanging wall and foot wall of the fault decreases rapidly, with deformation greater than 30cm within 50km across the fault zone. The uneven distribution of the vertical deformation has some peak values at near fault, mainly distributed at the southern section (Yingxiu), the middle (Beichuan) and the northern end (Qingchuan) of the seismogenic fault.