Shallow structural characteristics and spatial distribution of Xiadian fault
by shallow seismic reflection method

In order to further study the seismogenic structure and activity of Xiadian fault, the shallow seismic exploration is carried out in the epicenter of Xiadian fault with the seismic exploration lines of small trace interval and high density; and the seismic reflection profiles are comprehensively interpreted. The seismic exploration lines are laied toward both sides with Pangezhuang as center. There are 12 seismic exploration lines with a total length of about 18 km. Field data acquisition geometry is intermediate excitation and bilateral asymmetric reception with no less than 12 full coverages. Through the normal and fine processing, the reflected wave stacking time sections are acquired, revealing the wave group variation characteristics and the clear fracture features. Xiadian fault is interpreted as normal fault with dip SE, apparent dip angle about 72°. Meanwhile, the stacked time sections also show the shallow structural characteristics and distribution of Xiadian fault from Xiaoshigezhuang to Nanzhangdai, about 20 km long. The fault strike is about N40°E in exploration line scope. Therefore, it is inferred that Xiadian fault is a Holocene active fault according to the microtopographic survey and previous research findings. As for the center section of Xiadian fault, secondary fault develop and diffracted waves appear obviously, and weaken toward the two sides, which is coincident with the distribution of fault scarp and continuous elevation changes, verifying that the epicenter was located near Pangezhuang, Xiadian town. The spatial distribution of Xiadian fault and the strata structure features revealed by exploration agree well with geological data.