Using historical remote sensing images for detailed tectonic geomorphological interpretation in the study of active faults: Application to the Xiaojiang fault case study

The northern section of the Xiaojiang fault is the most active section in the Xiaojiang Fault Zone, and a detailed interpretation of this fault is highly important. In this work, KeyHole-4B images and Landsat 8 images of the northern section of the Xiaojiang fault were collected, and remote sensing interpretation and tectonic geomorphological analysis of the northern section of the Xiaojiang fault were carried out to obtain a more detailed fault distribution. The results reveal that the northern section of the Xiaojiang fault is a group of faults that are subparallel to each other with a space of 2–4 ​km. The fault is located along the Jinshajiang Valley and the Xiaojiang Valley. At the same time, we counted the large-scale left-lateral dislocations of the gullies and ridges. Combined with the results of previous studies, the long-term average slip rate of the northern section of the Xiaojiang fault is 6.2 ​± ​1.1 mm/a since the late Middle Pleistocene, 11.4 ​± ​2.8 mm/a since the middle of the late Pleistocene, and 8.0 ​± ​2.0 mm/a since the middle and late Pleistocene. The high slip rate in the northern section of the Xiaojiang fault represents the response of the local strain of the central Yunnan subblock, which rotates clockwise along the boundary fault. This finding is consistent with the pattern of northwards and north-east wards thrusting of the Indian plate, leading to eastwards extrusion and the escape of material from the Qinghai-Xizang Plateau.