1. a Department of Resources and Environment , Capital Normal University , Beijing 100037, P.R. China
2. b Key Lab. of Resources Environment and GIS , Beijing City , Beijing 100037, P.R. China
3. c Key Lab. of 3D Information Acquisition of Education Ministry of China , Beijing 100037, P.R. China
4. d Institute of Crustal Dynamics , China Seismic Bureau , Beijing 100085, P.R. China