Dynamic characteristics of fault-controlled earth fissure sites in Jingyang County, Weihe Basin, China

Jingyang County is located in the northern part of the Weihe Basin, which is an important part of the Fen-Wei graben system. Nearly half of earth fissures located in northern Jingyang County have East–West orientations that match the orientation of the nearby Kouzhen–Guanshan active fault. In order to analyze the superficial structures and dynamic characteristics of earth fissures, we conducted trenching and microtremor testing at two earth fissure sites that are largely controlled by activity along the Kouzhen–Guanshan fault. Our main results are as follows: (1) The presence of earth fissures has little to no effect on the predominant frequencies and natural periods that excite the maximum response acceleration during a microtremor. (2) Three specific amplitudes, including the Fourier amplitude at the predominant frequency, the maximum response acceleration, and the Arias intensity, are smaller at site 1 than they are at site 2. (3) Amplification occurs at both earth fissure sites. These three amplitudes have high values at distances less than ~ 6 m from the crack, attenuated values at distances of ~ 6–20 m from the crack, and low stable values at distances greater than ~ 20 m away from the crack. (4) We calculated the amplification factors for these two earth fissure sites and identified regions that experience varying degrees of this amplification. Based on our analysis, we recommend seismic fortifications for buildings in areas affected by these earth fissure sites.