Assessing post-seismic hillslope stability with finite element methods

Earthquakes can induce a legacy effect on hillslopes by reducing rock mass shear strength through fracture development and cohesion loss, thereby increasing landslide susceptibility. While methods for modeling shear strength reduction exist, post-seismic landslide susceptibility assessments that account for this earthquake legacy effect remain unexplored. In this study, we address this gap by performing regional-scale slope stability analyses using Finite Element Methods (FEM). Focusing on the area affected by the 2023 Türkiye earthquake, we conduct back-analyses to estimate the shear modulus of hillslopes that failed during the event. Using an empirical relationship for shear strength reduction, we estimate post-seismic shear strength and integrate these parameters into FEM simulations to evaluate hillslope deformation. The deformation results are subsequently used to assess landslide susceptibility across the region.

This study represents the first application of FEM for regional-scale landslide susceptibility analysis, systematically accounting for changes in rock mass strength due to seismic events. The proposed framework enhances the accuracy and reliability of post-seismic slope stability assessments, providing a step forward in regional-scale, post-seismic landslide hazard evaluation.