One-at-a-Time Sensitivity Analysis for Probabilistic Fault Displacement Hazard

Surface faulting poses an earthquake-related hazard with direct consequences for infrastructure and high-risk facilities. Probabilistic Fault Displacement Hazard Analysis (PFDHA) is widely used to estimate the annual frequency of exceedance (AFOE) of specific displacement values at sites on or near active faults. This approach requires numerous input parameters related to fault characterization and coseismic displacement distribution, yet few studies have examined how these parameter choices affect hazard results. Thus, we conduct an analysis following a One-At-a-Time (OAT) strategy, in which a single parameter is varied with respect to three kinematic-specific baselines. We explored the PFDHA outputs obtained allied to the broadly adopted regression models and scaling laws available in the literature up to 2023. We compared the hazard curves obtained for principal faulting from each calculation to a baseline parametrization, and we computed the percentage difference in AFOE, given a displacement amount, with respect to such a baseline. We obtained values in the interval -100% to +200%, computed within the displacement interval adopted for the hazard calculation, attesting that empirical regressions contribute significantly to hazard curve variations. Our sensitivity study could inform operative choices by practitioners and provides insights for optimizing data acquisition efforts in fault displacement hazard assessments.