Studies on the Velocity Structure of Crust-Upper Mantle beneath Eastern Qinghai-Tibet Plateau Using Seismic Tomography

Seismic tomographic analysis is performed using the teleseismic data acquired from the eastern QinghaiTibet plateau in 1998. Inversion results of tomography and receiver functions show a gradually southward increasing in crustal thickness in a stepping manner. The analysis on the residual approves that the QinghaiTibet plateau has a thick crust, especially and it is thicker in the south and west than in the north and east. The Eastern Kunlun Fault and other faults match the boundaries between high velocity and low velocity bodies. An overwhelming low velocity perturbation (up to -3 %) bctwecn the depth of 100 km and 400 km beneath the Eastern Kunlun Fault Belt with its north end corresponding to the southern part of the Eastern Kunlun Fault with its north end cuts in northeast through the high velocity lithosphere and connects to low velocity materials coming deeply from the mantle. Beneath the Qiangtang terrane on the south of the Jinska suture, distributes the other low velocity perturbation above the depth of 200 km.