Late Quaternary Activity Studies on the Lintong–Chang’an Fault Zone in the Weihe Graben, Central China, Using Combined Techniques

Abstract

The Lintong–Chang’an Fault Zone (LCFZ) is an important active structure in the Weihe Graben (central China). The study on the activity of the LCFZ is not only of great significance to explore the regional tectonic mechanism, but also has practical value in urban seismic mitigation and disaster relief. In this study, based on high-resolution remotely sensed imagery, shallow seismic reflection survey, borehole data and excavation of a foundation pit, we determined the distribution and activity of the Wangjiabian–Houjiawan fault (a branch fault of the LCFZ) in the Shaoling Loess Tableland. Combined with previous studies, we further inferred that the vertical displacements were 0–6 m along the LCFZ, but most displacements were around 1 m. Furthermore, there are eight locations where no displacements have been found in the Late Pleistocene strata. The offsets on the fault zone since the Late Pleistocene display a wave-like pattern, which is unrelated to the regional topographic expression. Compared to other faults in the Weihe Graben, the activity of the LCFZ in vertical component is relatively weak, implying a possible strike–slip motion. In addition, a major active fault may exist on the northwest side of this fault zone, bearing part of the fault motion in this region.