Assessment of Community Risk from Seismic-Induced Damage to Hazardous Materials Storage Tanks in Marine Ports

Marine ports located in regions of moderate seismicity can face high Natech (natural hazard-triggered technological) risk because large inventories of hazardous materials are stored near dense urban populations. This study proposes and applies a Natech risk framework to a representative port on the Saint-Laurence River in Quebec, Canada. Site-specific peak ground accelerations (PGA) are first estimated for 12 earthquake scenarios using regional ground motion prediction equations adjusted for local site conditions. These hazard levels are combined with a damage probability matrix to estimate Hazardous Release Likelihood Index (HRLi) scores for atmospheric steel storage tanks. Offsite consequences are then evaluated to obtain Maximum Distances of Effect (MDEs) for different types of hazardous materials. MDE footprints are intersected with block-level demographic data and complemented by a domino-effect based on inter-tank spacing, yielding a tank-level Natech Risk Index NRIi,s for each storage tank (i) and seismic scenario (s). These values are then averaged over all tanks to obtain a scenario-level mean Natech Risk Index (NRI¯) for each tank substance. Regression equations relating NRI¯ to PGA are provided as a practical tool for defining critical intensity thresholds for seismic Natech risk management in marine ports.