This study investigates the influence of key numerical simulations on the stability of the Stava tailings dam, which collapsed in Italy in 1985. Initially, a finite element method (FEM) simulation was conducted to assess the combinations of material parameters and ground water level that bring the dam close to failure, i.e. that give a Factor of Safety (FOS) close to 1. Parametric analyses with FEM provided a preliminary assessment of the shape of failure surface for different material shear strength parameters and by varying the water height within the dam, offering insights into the relationship between water levels and safety factor. However, FEM faced limitations in capturing large post-failure deformations due to the challenges in quantifying displacements and failure surfaces. To address these limitations, the Material Point Method (MPM) was employed. The initial stress state for MPM analysis is mapped from FEM using the new procedure available in Anura3D2024 [1]. The MPM simulation successfully modelled the large-scale displacements enabling a more comprehensive analysis of the dam's failure mechanics using the geometry based on the upstream construction method providing valuable guidelines for understanding the factors influencing the stability of tailings dams when analysed through MPM.