EXPLOSION SEISMIC STUDY OF THE CRUSTAL STRUCTURE IN FUZHOU-QUANZHOU-SHANTOU REGION
LIAO QI-LIN WANG ZHEN-MING WANG PING-LU YU ZHAO-KANG(Seismological Bureau of Fujian Province, Fuzhou)WU NlNG-YUAN (State Seismological Bureau, Beijing)LIU BAO-CHENG(Departnent of Geophysics, Peking University, Beijing)
Based on the analysis of the D. S. S. data obtained from Fuzhou-Quanzhou-Shantou region in 1982 and 1985, nine wave groups have been identified as P1, Pg, P'g, P3°, P4(P4°), P5°, Pn(Pn°), P7* and S. The models of the crustal and upper mantle structure in the region have been obtained with direct invesion and calculations of the travel time and synthetic seismogram and ray traceing.The result shows that in the region, the crustal structure is of the characteristic of the transitional zone of the continental margin. The P-wave velocity and thickness of the crust, which is composed of three layers of 3 km, 15 km and 12 km, thicknesses are respectively 6.3 km/s and 30.0 km. Pn velocity is 7.90 km/s. In the mid-crust there is a low velocity layer which is 3.0-4.0 km thick and with velocity 5.50-5.90 km/s. It is found that there is a close relationship between the distribution of the low velocity layer and the hot spring. In the lower part of the lower, crust, there is a high velocity and dense layer several kilometers thick. It is a mixture of crust and mantle materials which resulted from the upwelling and transporting of the upper mantle material.The structure and fluctuation of Moho as well as the distribution of the faults are also discussed in the paper.