The 3‐D Structure of Shear Waves in the Crust and Uppermantle Beneath East Chinese Continen‐tal Inverted by Rayleigh Wave Data

Abstract

AbstractThe phase velocity dispersion of seismic surface waves is computed from the clear and reliable Rayleigh wave records of 21 seismic stations and 43 paths in east Chinese continent. We obtain the distribution of phase velocity dispersion by Talantola probability inversion method. The image of 3‐D shear wave velocity in the crust and upper mantle is inverted by the phase velocity dispersion curves in the investigated region. Then we obtain the S wave velocity structure in the crust and upper mantle of east Chinese continent. The results show that the over all tendency of the thickness of east China crust is thin in the east and thick in the west. To the west of 105° E, the thickness of crust gradually increases to 55km. There is an ‘h’ form slope belt of the crust thickness. In the region of west Henan and south Shanxi provinces the crust is relatively thin. The thickness of crust in Dabie mountain and Taishan mountain are thicker than surrounding region. But in the Qinling mountain region the crust is not thicker. In North China region the top interface of the low velocity layer (LVL) of the upper mantle is rather shallow. It is about 80–90km. In the region of Eerduosi depression, Sichuan platform trough and Guizhou‐Hunan region it is about 120–130km. In the east Yangzi block as well as east and center South China fold system velocity in the top upper mantle is relatively low and the velocity contrast of LVL is not evident. In the west of Yunnan‐Guizhou fold system there is no LVL within the top 200km of the upper mantle.