Crustal anisotropy beneath northeastern margin of the Tibetan Plateau and its dynamic implications

We present anisotropy results using Ps phase in receiver functions, which are computed from the data of 81 seismic stations in northeastern margin of Tibetan Plateau. We use a modified automatic shear-wave splitting method to compute the anisotropic parameters using selected Ps phase. We would like to discuss about dynamic mechanism in this area using crustal anisotropy associated with the result of SKS-splitting and surface constraints like GPS velocity. The result can be summarized as follows. The large delay times imply that the crustal anisotropy is mainly derived from middle to lower crust rather than upper crust. In the southeastern part of the research area, crustal anisotropy agrees well with the result computed form SKS phase and GPS velocity directions trending NWW-SEE or E-W. This result implies a vertically coherent deformation in the area as the directions of crustal anisotropy trend to be perpendicular to the direction of normal stress. In the middle and north part of the research area, the fast polarization direction of crustal anisotropy is NEE-SWW or E-W, parallels the direction of GPS velocity, and differs from the direction of the result of XKS-phase. This result implies that decoupled deformation in this area is associated with middle to lower crustal flow.