Relationship Between Activity of the Yuanmou Fault and Earthquake-induced Geological Disaster During the Late Quaternary

The Yuanmou Fault is an important active fault, which is located at the southwest part of the south-north- trending earthquake belt. Field investigations and geomorphic analyses showed that the Yuanmou fault is characterized by the transtensional left-lateral strike-slipping in the north, the simple shearing at the central part and the overall uplift in the south due to the compressional deformation. The variable activities of different sections of the Yuanmou Fault revealed the southward decline of active intensity since the late Pleistocene. Thus, the earthquake-related geological disasters in these three sections also show different deformational types with the birth and recurrence of landslides, collapse and ground fracture in the north, debris flow, recurrence of paleolandslides, local collapse and liquefaction in the central part, and collapse along the fault damage zone and local debris flow in the south. The late Quaternary activities and earthquake-induced disasters of the Yuanmou Fault suggested that the segmentation may control significantly the hazard types, distribution pattern and seismic risk in the future. The northern segment is prone to trigger large- and moderate earthquakes, and gradually propagate southward. The findings concerning the late Quaternary seismic activities and geologic hazards of the Yuanmou Fault would throw light on the understanding of the tectonic movement, earthquake mechanism and geomorphic response of the active tectonics in the southeastern Tibetan Plateau, and contribute to the engineering site selection and disaster prevention. © 2021, Science Press. All right reserved.