Risk prevention and management in the Silla landslide (Italy)

This note describes the activity of risk prevention and emergency management carried out since November of 1994 following the reactivation of a large landslide near Sills (Gaggio Montano, Bologna, Italy). The slide occurred on the upper part of a slope just above another landslide which remained dormant. Possible connection of the two slides with the consequent global reactivation of movement constitute conditions of high risk. This eventuality would have unavoidable consequences on the structures and infrastructures in the valley bottom, taking into account the probable blockage of the Silla stream at the slope toe. During the emergency phase some scenarios were defined on the basis of some indicators measurable with field surveys or with monitoring systems. For each scenario the potential damage was assessed and the risk mitigation activities were programmed.