Human health implications of cascading effects in chemical plants triggered by seismic NaTech events

Industrial chemical plants are currently both strategic assets and significant threats to human lives in the event of NaTech incidents such as earthquakes. The location of industrial plants is typically driven by economic or logistical considerations, often overlooking site-specific hazards and proximity to populated areas. Although industrial plants comprise numerous structural and non-structural elements with significant vulnerabilities, this study specifically focuses on the seismic behaviour of steel tanks. These tanks are particularly critical due to their capacity to store large volumes of potentially hazardous substances. The seismic performance of steel tanks varies significantly depending on key design properties, such as slenderness ratio, the presence of supporting legs, floating roofs, and, in some cases, the incorporation of innovative devices like seismic isolators or damping systems. This research presents a set of fragility curves for different tank typologies, offering a comprehensive analysis across a broad range of tank types. During an earthquake, the damage or collapse of steel storage tanks can trigger cascading effects, including the release of toxic substances that pose severe risks to workers and nearby populations. This study introduces and applies a novel holistic methodological framework to quantitatively assess the health impacts resulting from hazardous substance releases in chemical plants. It estimates environmental contamination levels, human exposure profiles, and the potential health effects on both workers and surrounding communities following exposure to these chemicals.