1. College of Geography Science, Nanjing Normal University, Nanjing 210097, China.
2. Department of Geology and Geophysics, University of Minnesota, MN 55455, USA.
3. State Key Lab of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 71005, China.
4. Department of Civil and Structural Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong.