1. Ph.D. Candidate, Institute of Earthquake Protection and Disaster Mitigation, Lanzhou Univ. of Technology, Lanzhou 730050, China.
2. Professor, School of Sciences, Lanzhou Univ. of Technology, Lanzhou 730050, China.
3. Professor, Institute of Earthquake Protection and Disaster Mitigation, Lanzhou Univ. of Technology, Lanzhou 730050, China (corresponding author).