Abstract:The middle south section of the Jiali- Chayu fault is located in an intensive uplift alpine topography area. Due to the dense vegetation, unclear fault landforms, and lack of Quaternary sediments, which hinder understanding of the geometric distribution of fault and seismicity. Based on the remote sensing interpretation, faulted landforms and soft- sediment deformation structures in Late Quaternary lacustrine, and geophysical sections, 〖JP2〗paleoseismic trench, OSL and 14C dating of sediment, at least two paleoseismic events were revealed with ages between 16. 13±1. 06~15. 66±0. 92 ka and 8630±600~9561±37 aB. P. , respectively. According to the geological survey combined with the available data, at least five paleoseismic events occurred since 〖JP2〗the late Quaternary in the middle- south section of Jiali- Chayu fault.These were dated to 16130~15660 a, 11060 a,〖JP〗8630~9561 a B. P. , 2780~2160 a B. P. and 650 aB. P. , with an earthquake recurrence period of about 2000~5000 a. GPS data show that the horizontal slip rates of the middle and southeast sections of the Jiali- Chayu fault are 1. 3~2. 0 mm/a and 2~4 mm/a, the compression〖JP〗 rates are 2. 5~2. 9 mm/a and 5. 1~6. 2 mm/a. Both are dextral compression, and there are two faults in north and south. The fault activity is obviously controlled by the eastward escaping of the Tibetan Plateau and clockwise rotation around the eastern Himalayan syntaxis. The Jiali- Chayu fault is characterized by slow strain accumulation and long recurrence interval. Considering that the top of eastern Himalayan syntaxis is still in a high state of structural compression, there is a possibility of an earthquake (M≥7) in the future.
