The new alarm about the landslide in Niscemi, geologists say: "It cannot be stabilized"

"The analyses conducted confirm that, due to the size of the landslide system, the depth of the sliding surfaces, and the geological characteristics of the involved soils, it is technically impossible to achieve a definitive stabilization of the entire slope through extensive structural interventions." This is stated in the second report by the professors from the University of Florence, led by geologist Nicola Casagli, commissioned by the Department of Civil Protection of the Prime Minister's Office to draft a report on the disaster that struck the municipality of Niscemi in Sicily last January.

For geologists, the management of instability must therefore be based on risk mitigation strategies and an adaptive approach, based on continuous monitoring and control of the main instability factors, through a balanced and progressive combination of structural interventions and non-structural risk reduction measures. One of the processes currently underway is the recession of the slope formed during the paroxysmal phase of the movement. According to experts, interventions should therefore not aim to reconstruct the original morphology, but rather accompany the evolution of the slope through reprofiling, surface water management, and erosion protection. At the same time, the reactivation of deep movement along already established sliding surfaces remains possible. Mitigation strategies must therefore primarily focus on water control. In the medium term, the proposed interventions are aimed at reducing infiltrations, capturing water emergencies, managing stormwater, and protecting against erosion at the foot of the slopes.

In the long term, only a more in-depth geological and geotechnical characterization will allow for the design of any targeted structural works, which, however, will only be able to act locally and will not guarantee a global stabilization of the system. The structural interventions proposed by the scholars particularly concern the control of the hydrogeological conditions of the slope: the reorganization of the sewage and aqueduct networks in the town of Niscemi, the construction of drainage systems through extraction wells and deep drainage tunnels, the reprofiling of the slopes, and local stabilization interventions of the slopes. At the same time, hydraulic works for the management of watercourses are planned, particularly for the Benefizio stream, aimed at reducing erosion and controlling the energy of runoff.