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Spatial slip rate distribution along the SE Xianshuihe fault, eastern Tibet, and earthquake hazard assessment
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  • Mingkun Bai,
  • Marie-Luce Chevalier,
  • Philippe Hervé Leloup,
  • Haibing Li,
  • Jiawei Pan,
  • Anne Replumaz,
  • Shiguang Wang,
  • kaiyu li,
  • Qiong Wu,
  • fucai liu,
  • Jinjiang Zhang
Mingkun Bai
Institute of Geology, Chinese Academy of Geological Sciences
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Marie-Luce Chevalier
Institute of Geology, Chinese Academy of Geological Sciences

Corresponding Author:[email protected]

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Philippe Hervé Leloup
Laboratoire de géologie de Lyon, Université de Lyon 1
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Haibing Li
Institute of Geology, Chinese Academy of Geological Sciences
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Jiawei Pan
Institute of Geology
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Anne Replumaz
ISTerre, Université Grenoble Alpes
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Shiguang Wang
National Institute of Natural Hazards, Ministry of Emergency Management of China
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kaiyu li
Institute of Geology, Chinese Academy of Geological Sciences
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Qiong Wu
Institute of Geology, Chinese Academy of Geological Sciences
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fucai liu
Institute of Geology, Chinese Academy of Geological Sciences
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Jinjiang Zhang
Peking University
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Abstract

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. 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 Zheduotang and Moxi 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 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 3.7-5.4 mm/yr on the Zheduotang fault and of 10.4-14.8 mm/yr on the Moxi 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 >10.4 mm/yr (Moxi fault). We eventually propose a new model for the SE Xianshuihe fault, where the large-scale Mugecuo pull-apart basin lies within an even larger scale compressive uplift zone in the XSH fault’s restraining bend, where the highest peak in eastern Tibet is located (Gongga Shan, 7556 m). Our slip rates determination allows to estimate a relatively high regional earthquake hazard of Mw~7 at present in the SE Xianshuihe fault.
Nov 2021Published in Tectonics volume 40 issue 11. 10.1029/2021TC006985