SEISMIC WAVE VELOCITY OF LOCAL EARTHQUAKES AND CRUSTAL STRUCTRUE IN SHANDONG AREA

In this paper, based on 90 earthquakes oecured in Shandong area and recorded by Shandong seismic network and some other stations in its adjacent provinces, the following results are obtained: 1. The P wave velocity and focal depth distribution of the 96 earthquaken show that there is a characteristic of multylayer structure in the crust in Shandong area. The mean propagation velocity of wave is: V_p=0.18KM/S, V_S=3.0KM/S. 2. Based on reflection wave P₁₁, S₁₁ and refraction wave P_n、S_n, from a single-layer crust model, the velocity of refraction and reflection waves are obtained. V_P11=6.43KM/S, V_S11=3.72KM/S, V_pn=8.02KM/S. The mean crustal thickness in Shandong area obtained by reflection wave and refraction wave data is 30.0KM. Through the single point caleutation for refraction wave, the crustal thickness obtained for western and central Shandong areas is large, while the crustal thickness for Yishu belt and the coastal area is relativety thin.