Towards a unified Probabilistic Fault Displacement Hazard Assessment: combining physics-based simulations and OpenQuake engine implementation.

Accurate estimation of surface fault displacement hazards is a key component of seismic hazard and risk assessment, especially for linear infrastructures and high-consequence facilities. Traditional approaches to Probabilistic Fault Displacement Hazard Assessment (PFDHA) have relied on empirical datasets and statistical models; however, recent developments highlight the importance of integrating physics-based modeling with advanced computational frameworks. Recent studies by Moratto and Peruzza (2024) and Chen et al. (2025), conducted within the PRIN Project NASA4SHA, represent complementary advances in this direction. The former improves the mechanistic understanding and modeling of dip-slip permanent ground displacement, while the latter introduces a computational infrastructure for probabilistic hazard integration within the OpenQuake Engine. Together, these contributions enable the development of transparent, reproducible, and physically grounded PFDHA workflows. These advancements also enhance the understanding of active compressive tectonic systems in Northern Italy and contribute to more robust seismic hazard assessments for critical infrastructure. Ongoing testing and prototypal applications further support the practical implementation of these methodologies.