1. Professor, Disaster Prevention Research Institute, Kyoto Univ., Kyoto 611-0011, Japan.
2. Assistant Professor, Disaster Prevention Research Institute, Kyoto Univ., Kyoto 611-0011, Japan (corresponding author). E-mail: wanggh@landslide.dpri.kyoto-u.ac.jp
3. Associate Professor, Disaster Prevention Research Institute, Kyoto Univ., Kyoto 611-0011, Japan.
4. Graduate School of Science, Kyoto Univ., Kyoto 611-0011, Japan; formerly, Doctoral Student.