CRUSTAL STRUCTURE OF THE CENTRAL PART OF NORTH CHINA PLAIN AND THE HSINTAI(邢台) EARTHQUAKE (Ⅰ)
TENG CHI-WEN FENG CHIN-FEN LI KIN-SUN CHEN HSUEH-PO WEN KUN-TI CHANG KIA-JU HSING CHENG-CHUN et al.
In order to study the deep crustal structure of the Central part of North China Plain, a profile of deep seismic sounding has been made. This profile starts from Yuanshih Hsien (元氏县), Hopei Province, at its west end and Tsinan, Shantung Province at its east end. The total length is about 270 km.On the profile are 9 shooting points, constituting a continuous system of observations by correlative meeting and pursuing recording. Based on the kinematic and dynamic characteristics of the waves, we can recognize many primary reflected and head waves, together with multiple reflected waves. In this region, the crust can be divided into seven layers of alterate higher and lower velocities. The overage thickness of the crust is 35-36 km. The overlying material has an average velocity of 6.0 km/sec, while the layer velocity of the top of upper mantle is 8.1 km/sec.In this region, the crust is composed of an inhomogeneous medium of many layers. It consists of intercalated layers of high velocity gradients.Finally, it is given here the velocity distribution in the crust and in the upper mantle together with a model of the crust.