Numerical Analysis of Cervo Cliff Stability Due to Basal Marine Erosion

Summary

Abstract

This study presents a comprehensive numerical analysis of a retreating sea cliff located along the SS1 “Aurelia” in the Italian Municipality of Cervo (Imperia, Liguria Region), situated between Capo Mimosa and the town of Andora (Savona). The study area is directly exposed to atmospheric and marine processes, such as the hydrodynamic action of sea waves, sea spray and tidal cycles, which are responsible for rock weathering and cliff erosion. The cliff has experienced several instability events, the most recent being in November 2023 and March 2024, thus posing a potential threat to nearby structures and infrastructures. Of particular concern is a building situated directly above the cliff, where the risk of structural instability is exacerbated by the ongoing erosion at the toe of the cliff. The simulations were carried out using the Finite Element Method (FEM) implemented within the Rocscience RS2 code. Due to the inaccessibility of the cliff, a detailed in-situ investigation was not possible. Thus, the geometry of the considered cliff section, as well as the structure of the rock mass, were assessed via a drone flight survey. The geotechnical parameters were assigned according to the results of an extensive literature review and an experimental campaign on samples collected via coring 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. The study aims to predict future cliff instability by simulating the progressive retreat of the basal notch generated by the erosion process. To this aim, several incremental erosional stages were modelled to identify potential failure scenarios under continued natural degradation. The results offer insights into the failure mechanisms of the coastal cliff.