1. Ph.D. Student, Dept. of Earth, Ocean and Atmospheric Sciences, Univ. of British Columbia, 2207 Main Mall, Vancouver, BC, Canada V6T 1Z4 (corresponding author).
2. Emeritus Professor, Dept. of Earth Ocean and Atmospheric Sciences, Univ. of British Columbia, 2207 Main Mall, Vancouver, BC, Canada V6T 1Z4.
3. Professor, Dept. of Civil and Environmental Engineering, Univ. of Illinois, 205N Mathews Ave., Urbana, IL 61801-2352.
4. Ph.D. Student, Dept. of Civil and Environmental Engineering, Univ. of Illinois, 205N Mathews Ave., Urbana, IL 61801-2352.