1. Assistant Professor, Dept. of Civil and Environmental Engineering, Univ. of Florence, 50121 Firenze, Italy (corresponding author).
2. Postdoctoral Research Fellow, Dept. of Physics “Enrico Fermi,” Univ. of Pisa, 56126 Pisa, Italy.
3. Assistant Professor, Dept. of Physics “Enrico Fermi,” Univ. of Pisa, 56126 Pisa, Italy.
4. Assistant Professor, Dept. of Civil and Environmental Engineering, Univ. of Florence, 50121 Firenze, Italy.