3d s-wave velocity structurc of crust and upper mantle in the northern china and its adjacent areas

In this paper,an inversion has been made of 3D S-wave velocity structure of crust and upper mantle in the northern China and its adjacent areas from long and middle period Rapleigh wave data respectively.The results show that the lateral inhomogeneity is very evident in crust,the characteristics of the active tectonics areshown in many district,but the leteral change of uppe mantle velocity structure has been lessened relatively.The crustal thickness In the studied region increases gradually from eastto west.The crustal average veloclty distribution framework corresponds with the distribution of the crustal thickness.The abrupt variation belt of crustal thickness and average velocity are basically identical with the distribution tendency of gradient belts of Bouguergr avity anomaly.From the value variation,the identity of Bouguer gravity anomaly and crustal thickness distribution is much higher than that of gravity anomaly and average velocity.Therefore,we candetermine that the fluctuation of Moho discontinuity is the main factor controlling Bouguer gravity anomaly.