1. Postdoctoral Fellow, Dept. of Civil Engineering, Johns Hopkins Univ., Baltimore, MD 21218 (corresponding author).
2. Professor, Dept. of Civil Engineering, Johns Hopkins Univ., Baltimore, MD 21218.
3. Research Engineer, Bundesanstalt für Wasserbau, 76187 Karlsruhe, Germany.
4. Associate Professor, Conservatoire National des Arts et Métiers, Paris 75003, France.
5. Postdoctoral Researcher, Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Catania, 95123 Catania, Italy.