Structural reliability approach to analysis of probabilistic seismic hazard and its sensitivities

This paper presents a new probabilistic framework for seismic hazard assessment and hazard sensitivity analysis. Hazard in this context means the probability of exceeding a measure of ground shaking intensity, such as peak ground acceleration and spectral acceleration. The main components of the proposed framework include structural reliability methods to estimate exceedance probabilities and their sensitivities, and multiple probabilistic models for earthquake occurrence, magnitude, location, and ground motion. This paper presents two analysis approaches. The first approach utilizes the first- and second-order reliability methods and importance sampling. This approach efficiently yields the hazard exceedance probabilities at a single site. The second approach employs the Monte Carlo sampling reliability method and yields the hazard exceedance probabilities at a multitude of sites in a single analysis, which is suited for large-scale seismic zonation. This paper also presents the probabilistic models that are suited for such analyses with an emphasis on characterization of epistemic uncertainties. Finally, novel sensitivity measures are proposed for hazard sensitivity analysis. These measures provide a framework to identify the most important uncertainties and guide the research to reduce these uncertainties over time. The proposed approach is validated and showcased by an illustrative example. The companion paper presents a comprehensive application to hazard analysis of Iran.