THREE DIMENSIONAL SHEAR WAVE VELOCITY AND ANISOTROPY OF CRUST AND UPPER MANTLE IN THE CHINA NORTH-SOUTH EARTHQUAKE BELT
CHEN LI-HUA SONG ZHONG-HE AN CHANG-QIANG CHEN GUO-YING(Institute of Geophysics, State Seismological Bureau, Beijing 100081)ZHUANG ZHEN Fu ZHU-WU Hu JIA-FU Lu ZI-LING(Yunnan University, Kunming 650091)
In this study, the three dimensional shear wave velocity in the China north-south earthquake belt and the neighbor area is inverted by useing long period date of 763 seismograph. Ray-leigh wave dispersion dates of 238 paths and love wave dispersion dates of 358 paths have been obtained by applying the "display-Equality filter frequency-time analysis" technique. The pure-path dispersions for 16 grids of 4°×4° grids in China have been extracted by using the modified "grid-dispersion inversion" method from the mixed-path dispersion dates. The results show 1. The thicknesses of the crust are about 40-50km, the thickest thickness is 65km, the depth of Moho deepen from east to west in tota area and from north or south to middle in west area. 2. Low velocity layers exist generally in the upper mantle, the depths are about 60-80 km. the thicknesses of layers above Low velocity layers are about 20-60 km, the velocities are about 4.30-4.50 km/s. 3. The anisitropy show that the differences of love wave and rayleigh wave velocity (V-VsH) increase with the depth.