1. Doctoral Candidate, The John A. Blume Earthquake Engrg. Center, Dept. of Civ. Engrg., Stanford Univ., Stanford, Calif. 94305; formerly Grad. Asst., Univ. of Colorado, Boulder, Colo. 80302
2. Prof. of Civ. Engrg., Univ. of Colorado, Boulder, Colo. 80302