1. Key Laboratory of Continental Collision and Plateau Uplift, Institute of Tibetan Plateau Research, Center for Excellence in Tibetan Plateau Earth Sciences, Chinese Academy of Sciences, Beijing 100101, China.
2. Department of Geophysics, Stanford University, Stanford, CA 94305-2215, USA.
3. Disaster Prevention Research Institute, Kyoto University, Uji, Kyoto 611-0011, Japan.
4. Department of Geological Sciences, University of Texas at El Paso, El Paso, TX 79968-0555, USA.