Development characteristics and formation analysis of the Liangjia Village earth fissure in the Weihe Basin, China

摘要

Liangjia Village earth fissure, one of the 79 earth fissures along the Kouzhen-Guanshan fault located in the northern Weihe Basin, causes severe damage to buildings and farmlands. Since the late 1950s, 40 earth fissures have occurred in a similar east-west (EW) direction parallel to the Kouzhen-Guanshan fault, and a further 39 earth fissures have occurred with north-west, east-north, or north-east orientations intersecting the fault. In this study, a case study of Liangjia Village earth fissure was conducted to investigate the mechanisms of fissure generation in detail. Geotechnical and geophysical methods including measurements, trenching, drilling, and seismic exploration were used to reveal the basic characteristics, geological background, and origin model of the Liangjia Village earth fissure. This earth fissure, with a total length of 800 m in 2014, runs EW parallel to the Kouzhen-Guanshan fault, and it has damaged buildings and farmlands by forming sinkholes, gullies, subsidence, and a scarp. The trenching results indicated that this fissure underwent multi-phase activity. Analysis of geological drilling and shallow seismic profiling results showed that the fissure also possessed characteristics of a synsedimentary fault. Regarding its genesis, the fissure was formed through the combined actions of three factors: an earthquake created the fissure, the Kouzhen-Guanshan fault controlled its development, and loess erosion and groundwater runoff subsequently enlarged the fissure. Regional extension first generated many buried faults along the hanging wall of the Kouzhen-Guanshan fault before seismic activity caused the buried faults to propagate to the surface, where loess erosion and ground-water runoff promoted the formation of the current earth fissure.