Risk Assessment of Oil Storage Facilities Exposed to Tsunami Hazard

The term NaTech was coined to describe events where natural hazards trigger technological accidents in industrial facilities. Structural damage to the installations, caused by natural events such as earthquakes or tsunami, may cause loss of containment, which may in turn lead to fires, blasts, or dispersion of toxic gases. Thus, NaTech quantitative risk assessment (QRA) requires a measure of structural risk to provide estimates of future losses and a detailed assessment of the consequences arising from such losses. This paper presents an industrial risk analysis for anchored atmospheric storage tanks subjected to tsunami hazard, by means of a multidisciplinary approach integrating structural analysis and consequence assessment. This is performed for a case study consisting of a waterfront tank farm located at a coastal Italian site. The first part of the analysis requires calculation of the structural failure rate of storage tanks that suffer content release due to damage induced by tsunami inundation, via models of probabilistic hazard for the site of interest and the vulnerability (fragility) of the examined structures. Structural failure rates are evaluated for various numbers of simultaneous waterfront storage tank failures, using tsunami fragility curves for variable tank geometry and filling level. The failure rates and consequence analysis for the tank farm are then used as input parameters for the NaTech QRA, leading to the calculation of risk figures for tsunami hazard.