中国西部及邻区地壳上地幔波速和Q结构面波层析成像

This project summarized shear wave velocity and Q of crust and mantle of East China from surface waves dispersion and dynamic characters by suraface wave data analysis and treatment. We complete large software for tomography of crust and mantle by Equal Area Projection under WINDOWS platform. A fast algorithm has been brought forward for computing dispersion curves of surface waves. We also put forward an image method to get dispersion from the seismic recodes of surface waves as well as a method to get dispersion from the seismic recodes of higher mode surface waves. Surface wave dispersion data of western China were collected and treated. The results of tomography show that the average thickness of crust beneath Tibet plateau is 65 km. The deepest part of Moho can be reach 73 km. Velocity of lower part of crust under Tibet plateau is lower than other area. That may be explained by India Plate inserting under the crust of Tibet plateau. Velocity in upper mantle under Tibet plateau is distinctly lower than other area. There is also a distinct decrease of velocity under 150 km beneath Tibet plateau. Compare to other area this depth is deeper and velocity is lower. That means the thickness of lithosphereis thoicker than other area of China. Velocity in upper mantle at the south foot of west Himalaya is obviously higher. Thickness of crust under Talim basin，Tsaidam basin and Zhungeer basin are thinner. There is only a litter increase of crust thickness under Kunlun mountain, Tanggula mountain, Gangdise mountain and Himalaya mountain, it may reflect that these areas do not reach equilibrium status now.

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