1. Professor and Chair, Geological Engineering Program, Dept. of Civil & Environmental Engineering, Univ. of Wisconsin-Madison, 1415 Engineering Dr., Madison, WI 53706 (corresponding author).
2. Project Engineer, Ramón E. Zequeira & Associates, Asunción 513 Puerto Nuevo, San Juan, Puerto Rico 00920.
3. Professor, Geological Engineering Program, Dept. of Civil and Environmental Engineering, Univ. of Wisconsin-Madison, 1415 Engineering Dr., Madison, WI 53706.