Affiliation: | Department of Civil and Environmental Engineering and Geodetic Science, The Ohio State University 2070 Neil Ave, Columbus OH 43210-1275,;USA. E-mail: Department of Earth Sciences, Inst. of Geoinformatics and Geophysics, Sejong University, 98 Kunja-dong, Kwangjin-Ku, Seoul, 143–747,;Korea. E-mail: |