Spatial Variations of Deformation along a Strike-Slip Fault: A Case Study of Xianshuihe Fault Zone, Southwest China

Abstract

The distribution of damage zones around a fault has long been regarded as a frontier and hot spot in the field of geoscience but is still not fully understood. In this study, we conducted field investigations and tests around the Xianshuihe fault zone (XSHF), a left-lateral strike-slip fault with a length of about 400 km located in the eastern margin of the Tibetan Plateau. The results reveal that the fracture frequency and rock strength parameters present a spatially asymmetric distribution along the fault and have a negative power-law correlation with the distance from the fault. The widths of the damage zones are approximately 20.8 km and 17.1 km in the southwest and northeast directions, respectively. Combined with the previous studies, we presented a negative power-law function to depict the correlation between slip displacement and the width of the damage zone and found that the growth rate of damage zone in faults with low displacement is greater than that in those with large displacement. The study demonstrates that the asymmetric distribution of the damage zone surrounding the XSHF is mainly due to the stress redistribution in different damage zones stemming from the left echelon and different activity rates of the blocks on both sides of the XSHF.