Practical assessments of risk and its uncertainty

The practical aspect of quantitative risk assessment (QRA) is highlighted for natural hazard mitigation. Besides the estimation of the expected risk measure, the distribution of the risk associated with the epistemic type of uncertainty is equally important; the latter permits the decision maker the selection of a risk-averse measure in order to minimize the error (or increase the confidence) in the decision.-The process is illustrated with a hypothetical example of the risk assessment for New Orleans assuming that an assessment is performed in 1985; i.e., 20 years prior to the occurrence of Katrina in 2005. The process can also be applied to evaluate the reduction in the respective risks (for fatality, injury, and economic loss) accruable from an investment for mitigating future hazards. The practical implementation of QRA is emphasized.