1. School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta GA 30332
2. Pontificia Universidad Católica de Chile, Vicuña Mackenna 4860, Macul, Santiago, Chile
3. Civil Engineering Dept., University of Concepcion, Casilla 160-C, Correo 3, Concepción, Chile
4. Departamento de Ciencias de la Tierra, Universidad de Concepcion, Vistor Lamas 1290, Concepcion, Chile
5. Department of Civil Engineering, University of Patras, Rio, 26500, Greece
6. Universdad de Chile, Santiago, Chile