1. Dept. of Civil and Environmental Engineering (DICEA), Univ. of Florence, Via di Santa Marta 3, I-50139 Firenze, Italy.
2. Dept. of Civil and Environmental Engineering (DICEA), Univ. of Florence, Via di Santa Marta 3, I-50139 Firenze, Italy (corresponding author).
3. Dept. of Civil Engineering and Architecture, Univ. of Parma, Parco Area delle Scienze, 181/A, Parma, Italy.
4. Dept. of Earth Sciences, Borgo degli Albizi, 28, Univ. of Florence, I-50100 Florence, Italy.