Latest Quaternary Active Faulting and Paleoearthquakes on the Southern Segment of the Xiaojiang Fault Zone, SE Tibetan Plateau

Abstract The Xiaojiang fault zone (XJFZ) is an important part of the Xianshuihe-Xiaojiang system, acting as eastern boundary Chuan-Dian block on southeastern margin Tibetan Plateau and accommodating lateral extrusion block. faulting activity paleoseismic history southern segment XJFZ remain poorly understood. Here, trench excavations radiocarbon dating revealed that four recent surface-rupturing paleoearthquakes have occurred Jianshui (JSF) in since ~15370 yr BP. ages these events, labeled E4-E1 from oldest to youngest, are limited following time ranges: 15360-12755, 10845-6900, 1455-670, 635-145 BP, respectively. most event E1 was likely 1606 earthquake. These events appear occur unregularly time. interval between last two 726±235 yr, average recurrence for all 4589±3132 yr. deformed strata show JSF characterized kinematically by transtension, which respond apparent change direction clockwise rotation around Himalayan syntaxis. Combined with analysis neighboring NW-striking faults, our study suggests south-southeastward motion be firstly accommodated right-lateral shear dip-slip motions Qujiang Shiping faults continues across Red River zone, then transmitted southward along Dien Bien Phu fault. Therefore, plays a dominant role tectonic deformation block, high seismic hazard.