1. Geotechnical Engineer, Geocomp Corporation, 125 Nagog Park, Acton, MA 07120 (corresponding author).
2. Professor, Civil, Architectural, and Environmental Engineering, Drexel Univ., 3141 Chestnut St., Philadelphia, PA 19104.
3. Professor, Civil and Environmental Engineering, Univ. of California–Davis, One Shields Ave., Davis, CA 95616.
4. Graduate Research Assistant, Civil and Environmental Engineering, Univ. of California–Davis, One Shields Ave., Davis, CA 95616.