Modelling of slopes in the Ionian coastal area of Calabria region

Stratified coastal slopes characterized by permeable units overlying low-permeability layers are prone to instability driven by groundwater fluctuations and progressive failure processes. This study analyses a representative coastal cliff in southern Italy using a combined application of limit equilibrium methods (LEM) and finite element modeling (FEM) with the shear strength reduction technique (FEM–SSR). The numerical framework accounts for lithological heterogeneity and groundwater conditions, enabling a direct comparison of safety factors and failure mechanisms. Results show that LEM generally predicts higher stability margins and simplified failure surfaces, whereas FEM identifies strain localization and complex rotational–translational mechanisms concentrated near the calcarenite–clay interface. Sensitivity analyses confirm the dominant role of groundwater level variations and perched aquifers in controlling slope response. Field observations and recent geotechnical investigations support the adopted geological and hydrogeological model. Although no immediate instability is indicated, the analyses highlight a potential long-term susceptibility of the coastal slope under unfavourable hydrogeological conditions, providing a basis for hazard assessment and monitoring-oriented risk management.