Quaternary activity and seismic hazard of Liangyun fault in northwestern Hubei area

The Liangyun fault zone, as one of the largest and most influential faults in the northwestern Hubei area, is located in the uplifted area of Qinling fault block with a length of about 200 km. The structure has a sinistral strike-slip motion with obvious quaternary activities. The Yunxi M4.9 earthquake which occurred in 1964 may be resulted from the reactivation of the Liangyuan fault. However, the Quaternary activity of the fault is poorly studied, which affects the overall understanding of the neotectonic deformation pattern and strong earthquake risk in the northwestern Hubei area. Based on remote sensing interpretation, field investigation, and high-density electrical exploration, it was found that bead-like basins, negative fault long valleys, fault passes, fault scarps, and other morphological features are developed along the fault trace. The fault activity is obvious in the early and middle Quaternary sediments. The risk of moderate earthquake in the future should not be underestimated, although its activity in the late Quaternary is weak.