Spatial Slip Rate Distribution Along the SE Xianshuihe Fault, Eastern Tibet, and Earthquake Hazard Assessment

The Xianshuihe (XSH) fault in eastern Tibet is one of the most active faults in China, with the next large earthquake most likely to occur along its SE part, where the fault splits into three parallel branches: Yalahe, Selaha and Zheduotang (ZDT). Precisely quantifying their slip rates at various timescales is essential to evaluate regional earthquake hazard. Here, we expand our previous work on the Selaha fault to the nearby ZDT and Moxi (MX) faults, and add observations on the Yalahe fault and on the newly discovered Mugecuo South fault zone. Using tectonic‐geomorphology approaches with 10Be dating, we had previously determined average late Quaternary slip rates of 9.75 ± 0.15 and 4.4 ± 0.5 mm/yr along the NW and SE Selaha fault, respectively. Using the same methods here, we determine a slip rate of 3.4–4.8 mm/yr on the ZDT fault and of 9.6–13.4 mm/yr on the MX fault. This is consistent with the southeastward slip rate increase we had proposed along the XSH fault system from 6‐8 mm/yr (Ganzi fault) to ∼10 mm/yr (Selaha fault), and >9.6 mm/yr (MX fault). We propose a new model for the SE XSH fault, where the large‐scale Mugecuo pull‐apart basin lies within an even larger scale compressive uplift zone in a restraining bend of the XSH fault, where the highest peak in eastern Tibet is located (Gongga Shan, 7,556 m). Our slip rate determination helps to constrain a relatively high regional Mw ∼ 7 earthquake hazard at present on the SE XSH fault. Plain Language Summary The Xianshuihe (XSH) fault in eastern Tibet is one of the most active faults in China, with the next large earthquake most likely to occur along its southeastern part, where the fault zone consists of four parallel branches with complicated geometries. Studying the activity and slip rate of each branch is essential to evaluate regional earthquake hazard, especially because they cross a major city (Kangding), and because of the imminent construction of the Chengdu‐Lhasa railroad. Here, we expand our previous slip rate study on one fault branch (Selaha) to two additional ones (Zheduotang and Moxi), together with key observations on the newly discovered “Mugecuo South fault zone.” We find that the rate over the last ∼100,000 years may increase southeastwards along the XSH fault system, as previously suggested. The fast slip rates and their complex spatial distribution in the Kangding region reveal a high earthquake hazard (Mw ∼ 7) at present. Key Points We determined late Quaternary slip rates of 3