late quaternary activity of the qujiang fault and analysis of the slip rate

The Qujiang Fault is one of the most seismically active faults in western Yunnan, China and is considered to be the seismogenic fault of the 1970 M_S7.7 Tonghai earthquake. The Qujiang Fault is located at the southeastern tip of the Sichuan-Yunnan block. In this study, we examine the geometry, kinematics, and geomorphology of this fault through field observations and satellite images. The fault is characterized by dextral strike-slip movements with dip-slip components and can be divided into northwest and southeast segments according to different kinematics. The northwest segment shows right-lateral strike-slip with normal components, whereas it is characterized by dextral movements with the northeast wall thrusting over the opposite in the southeast segment. The offset landforms are well developed along the strike of the fault with displacements ranging from 3.7m to 830m. The Late Quaternary right-lateral slip rate was determined to be 2.3～4.0mm/a through dating and measuring on the offset features. The variation of the slip and uplift rates along the fault strike corresponds well to the fault kinematics segmentation: the slip rate on the northwest segment is above 3mm/a with an uplift rate of 0.6～0.8mm/a; however, influenced by the Xiaojiang Fault, the southeast segment shows apparent thrust components. The slip rate decreases to below 3.0mm/a with an uplift rate of 1.1mm/a, indicating different uplift between the northwest and southeast segments.