1. College of Geological Engineering and Surveying of Chang'an University/Key Laboratory of Western China; Mineral Resources and Geological Engineering; Xi'an 710054 China
2. Research Centre on Landslides, Disaster Prevention Research Institute; Kyoto University; Gokasho, Uji, Kyoto 611-0011 Japan
3. Department of Earth Sciences; Abbottabad University of Sciences and Technology; Abbottabad Pakistan
4. College of Environment and Civil Engineering of Chengdu University of Technology; Chengdu 610059 China