Abstract:Through processing and contrast analysis of 3 deep seismic sounding lines crossing Jiyang depression, we find that the crustal structure of Jiyang depression can be divided into three layers: upper, mid and lower crust. The Moho depth of Jiyang depression is about 31 km, and the interface variation is gentle. The deep tectonic is mirror symmetrical to the shallow tectonic. Low velocity bodies exist in the mid-crust of Jiyang depression, providing necessary conditions for the detachment development, and causing variations of crustallateral thickness between the upper crust and lower crust. The Moho interface feature differs between the Huimin sag and Dongying sag. In Huimin sag there is a P4 seismic phase before the Pm phase, which is the reflection of the crust-mantle transition zone. However, in Dongying sag the Pm seismic phase reflects the features of first order discontinuous interface. The result shows that the crustal structure of Jiyang depression has typical features of north China and that asthenospheric upwelling changes the Moho interface property of Jiyang depression.