Static and seismic numerical analysis of a shallow landslide located in a vulnerable area

The paper summarizes the work carried out to study the activity of a shallow, slow-moving landslide located on the lateral slope of an artificial reservoir. The work includes the description of an extensive geotechnical campaign to characterize the soils, the elaboration of monitoring data, and 2D numerical modeling of the slope in static and dynamic conditions using Finite Element Analysis. The results of the numerical study demonstrate that possible re-activations of the movement are mostly driven by hydrological factors, while earthquakes can accelerate the movements but bring about additional displacements within tolerable limits. The relative importance of the two spatial components of the earthquake has been investigated suggesting that, for the examined case, considering the vertical component does not produce appreciable displacement increments. On the contrary, the method adopted to define the seismic action causes significant differences in simulation results. Starting from the 'basic seismic hazard' or from a site-specific seismic-tectonic study brings about important differences in the selection of the reference earthquake for the seismic analyses and, consequently, on the predicted landslide displacements.