Structural features and tectonic activity of the Weihe Fault, central China

The study of tectonic activity holds great significance in assessing historical and modern seismic risks. The Weihe Graben is a significant intracontinental graben system in China, with numerous active faults that have caused a series of earthquakes, including the Huaxian great earthquake (M similar to 8.5) in 1556 with approximately 830,000 deaths. Despite the obvious spatial relationship between the Weihe fault (WF) and these earthquakes, detailed research on the fault is still lacking. Various techniques including remote sensing images, digital elevation model, shallow seismic lines, trench excavation, drilling sections, and optically stimulated luminescence dating, have been utilized to obtain the following results: (1) The WF passes through the scarp of the Weihe River terrace in the north of Xianyang and can be divided into east and west sections at Jinjia village; (2) The WF is a normal fault that strikes northeast and dips south with a dipping angle of 65 degrees-75 degrees; (3) The fault has been active during the Holocene; (4) The vertically offset and dating results suggest that the fault activity has gradually decreased since the late Pleistocene, and the vertical slip rate during the Holocene is only 0.04-0.13 mm/year.