Hige Resolution Surface Wave Tomography In China And Its Adjacent Land And Sea Areas

This paper deals with the high resolution surface wave tomography in china and its adjacent land and sea areas .subareas (Tibet, South China, North China, Northwest China, South China Sea, Japan Sea, Philippines Sea) as well as. 704 events(7.0 > M > 5.0) recorded at 58 digital seismic stations form CDSN,GSN,GDSN and GEOSCOPE network in Eurasia and west Pacific regions were used in this paper. Five thousands and sever hundred accurate surface dispersion curves were selected and employed for inversion. The high resolution 3-D shear wave velocity images in this area was constructed by inversion dispersion and show a notable lateral variation in the crust and upper mantle.The images of S wave velocity indicate that from the upper crust to the depth of 70km, the high velocity is displayed in the region of eastern part of East Asia and West Pacific marginal seas, in contrast, extremely low velocity is in the Qinghai-Xizang plateau and its surrounding areas. There exists a boundary of velocity decrease along the Mountain belt from Da-Xingganling to Taihangshan, Wulinshan, which coincides with the gravity gradient belt in NNE-SSW trend in East China. The low velocity anomaly chain is located along the convergence belt of Tethys from Mediterranean Sea, Turkey, Iran, Himalayan orogens, Burma, Indonesian Islands.The evolution and geodynamic process is so different between the eastern part and western part of the East Asia and West Pacific marginal seas by the boundary of longitude 110°E. The western part is the thickening convergent lithosphere caused by Indian subcontinent collided with the Eurasian continent, and the eastern part is disassembly causing the lithosphere thinning and extension arising from intrusion of asthenospheric material.