1. College of Surveying and Geo-Informatics, Tongji University, 1239 Siping Road, Shanghai 200092, China
2. Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu 610041, China
3. Faculty of Science and Technology, Lancaster University, Lancaster LA1 4YR, UK
4. Geography and Environment, University of Southampton, Highfield, Southampton SO17 1BJ, UK