1. Senior Researcher, Dept. of Civil and Environmental Engineering, Univ. of Catania, Viale A. Doria, 6, 95125 Catania, Italy (corresponding author).
2. Project Manager Engineer, Azienda Consorziale Servizi Etnei (ACOSET S.p.A.), Viale M. Rapisardi, 164, 95123 Catania, Italy.
3. Full Professor, Dept. of Civil and Environmental Engineering, Univ. of Catania, Viale A. Doria, 6, 95125 Catania, Italy.