1. Department of Earth Sciences, University of Florence, Via G. La Pira 4, 50121 Florence, Italy
2. Civil Protection Centre, University of Florence, Largo Fermi 1, 50142 Florence, Italy
3. Department of Geosciences, University of Padua, Via G. Gradenigo 6, 35131 Padua, Italy
4. Department of Civil and Environmental Engineering, University of Florence, Via di Santa Marta 3, 50139 Florence, Italy