The late quaternary slip rate and paleoearthquakes of the Cuopuhu section of the Litang-Yidun fault, western Sichuan

The Litang-Yidun fault is a left-hand strike-slip active fault that extends for about 130 km in the Sichuan-Yunnan rhombic block. Studying the tectonic activity history of the Litang-Yidun fault is helpful to understand the theory of material eastward escape-slip of the Qinghai-Tibet Plateau. In this paper, the Cuopuhu section of the Litang-Yidun fault is selected as the research object, and the paleo-seismic events of the Cuopuhu section are explored using methods such as field survey, trenching and ¹⁴C dating. Two exploration trenches were excavated at the foothills of Dongou mountain to identify the cutting relationship between faults, the strata, the sedimentary characteristics, the fault motion and other characteristics, combined with the ¹⁴C dating results, a total of 4 paleo-seismic events were identified. Event I occurred before BC3382±60a; Event II occurred between BC3382±60a~BC1094±51a; Event III and Event IV both occurred after AD1330±44a. According to the last glacial moraine ridge, the average slip rate of the Cuopuhu section since the Late Pleistocene is 4.15±0.5mm/a.