“…The second method, tends to consider, even if in a simplified way, the role played by the soil, in foreseeing the occurrence of a soil slip both on small and large scales. These kinds of models, which can be considered deterministic, take into account not only external factors, such as the rainfall amount, but also the geometrical features of the slope, the physical and mechanical behaviour of the soil and the mechanism of rainfall infiltration (Haefeli, 1948;Campbell, 1975;Montgomery and Dietrich, 1994;Bandis, 1996;Alonso et al, 1995;Delmonaco et al, 2003;Iverson and Major, 1987;Iverson, 2000;Salciarini et al, 2006).…”