1. Graduate Research Assistant, Dept. of Geological and Atmospheric Sciences, Iowa State Univ., 2027 Agronomy Hall, Ames, IA 50011 (corresponding author).
2. Associate Professor, Dept. of Geological and Atmospheric Sciences, Iowa State Univ., 3023 Agronomy Hall, Ames, IA 50011.
3. Professor, Dept. of Civil and Environmental Engineering, Colorado School of Mines, 232 Coolbaugh Hall, Golden, CO 80401.
4. Assistant Professor, Dept. of Civil, Construction, and Environmental Engineering, San Diego State Univ., San Diego, CA 92182; formerly, Postdoctoral Fellow, Dept. of Civil and Environmental Engineering, Colorado School of Mines, 1500 Illinois St., Golden, CO 80401.