1. School of Civil Engineering, Purdue Univ., West Lafayette, IN 47906; formerly, Indian Institute of Science, Bangalore 560012, India.
2. Dept. of Civil Engineering, Indian Institute of Science, Bangalore 560012, India; and Centre for Earth Sciences, Indian Institute of Science, Bangalore, India (corresponding author).
3. School of Civil and Environmental Engineering, Univ. of New South Wales, Sydney, NSW 2052, Australia.