Numerical Analysis of Cervo Cliff Stability Due to Basal Marine Erosion

This study presents a numerical analysis of a retreating sea cliff located along the SS1 'Aurelia' in the Italian Municipality of Cervo (Liguria Region, Italy), between Capo Mimosa and the town of Andora (Savona). The area is exposed to atmospheric and marine processes (wave action, sea spray and tidal cycles) that promote rock weathering and cliff erosion. Several instability events have occurred, the most recent in November 2023 and March 2024, posing a potential threat to nearby structures and infrastructures, including a building situated directly above the cliff where ongoing toe erosion may exacerbate structural instability. Numerical simulations were carried out using the Finite Element Method (FEM) implemented in the Rocscience RS2 code. Because the cliff is largely inaccessible, detailed in-situ investigations were not feasible. The geometry of the analysed sections and the main rock-mass structure were assessed via drone flight surveys. Geotechnical parameters were assigned based on an extensive literature review and an experimental campaign on cored samples collected at a nearby site belonging to the same geological formation. A back analysis of the most recent rockfall event was used to refine the mechanical parameters and calibrate the model. Future cliff instability was investigated by simulating the progressive retreat of the basal notch generated by erosion. Several incremental erosional stages were modelled to identify potential failure scenarios under continued natural degradation. The results provide insights into the expected failure mechanisms of the coastal cliff and support the identification of potentially critical conditions associated with notch development, with implications for risk awareness and the management of exposed elements along the SS1 corridor.