THE 3-D SHEAR WAVE VELOCITY STRUCTURE BENEATH THE EASTERN CHINA AND ITS ADJACENT SEAS
SONG ZHONG-HE AN CHANG-QIANG CHEN GUO-YING CHEN LI-HUA(Institute of Geophysics, State Seismological Bureau, Beijing 100081)ZHUANG ZHEN Fu ZHU-WU LU ZHI-LING HU JIA-FU(Deportment of Geophysics, Yunnan University, Kunming 650091)
In this paper, 238 long period Rayleigh wave records from 30 seismic stations and 75 earthquakes are selected. Matched-Filtering and improved Grid Dispersion Inversion are performed on these data to give the pure-path dispersion curves of group velocities in the periods from 10 to 113 secends. Finally, the 3-D velocity model to a depth of 170km is given, In this paper, only the results obtained in the eastern China and its margin seas are shown.The shear wave velocity structure reveals following characters: there appears the division of researched region into blocks in south-north directions with the latitudes about 40°-44°N, 28°-32°N, 2°N as thier boundaries and shows the beltform distribution along the strike of island arc. The different characters of velocity structure in crust and upper mantle closely relate to the division of the first and second order tectonic elements. In addition, it is found that the Bouguer gravity anomaly is mainly under the control of the distribution of Moho depth and the depth of low velocity layer in upper mantle has clear concerned with surface heat flow values.