Assessment and Mitigation of Risk From Low-Probability, High-Consequence Hazards

Abstract

Modern probabilistic risk assessment (PRA) of civil infrastructure supports risk mitigation policy by providing insight into the factors that govern performance of facilities subjected to severe events beyond the design basis and the relative efficiency of various options for risk mitigation. A fully-coupled risk assessment of a facility provides estimates of the annual probability of exceeding pre-defined performance levels, defined either in terms of quantitatively defined limit states or more qualitatively defined damage states. In the United States, utilisation of PRA is most mature in the area of seismic risk to buildings, bridges and industrial facilities. To reach its full potential as a basis for risk-informed decision-making, however, PRA must be extended to address individual facilities and civil infrastructure systems exposed to competing hazards so that strategies and investments in reducing competing risks can be optimised. Some of the challenges presented in this extension are discussed in this paper.