The Impact of Natural Hazards on the Security of Chemical Sites

• The performance of security elements impacted by natural hazards is investigated. • Quantitative data were obtained through expert elicitation. • Failure probabilities exceed 70% in the case of earthquakes and floods. • Routing time more than doubles in the presence of natural hazards. • Downtime due to natural hazards may increase vulnerability to physical attacks. The protection of chemical sites from intentional malicious attacks, as theft, arson, and sabotage, is of utmost importance, due to the high potential hazards deriving from the mismanagement of the hazardous substances handled and stored. Highly effective Physical Protection Systems (PPS) are usually installed to ensure the security of chemical sites. Specific approaches as Security Vulnerability Assessment (SVA) and Security Risk Assessment (SRA) are applied to manage security issues. However, while the impact of natural hazards on the safety of chemical sites has been extensively studied, their influence on security elements remains largely unexplored. In the present study, the potential impact of 7 different natural hazards on 17 physical barriers, technological systems, and procedures constituting the PPS of chemical sites is addressed. Expert elicitation has been used to quantitatively assess the possibility and probability of failure of security elements due to the impact of natural hazards. A survey was carried out, involving 61 respondents with multidisciplinary background and expertise. The likelihood of damage of the security elements considered estimated in the survey is on average 10% and is higher than 40% for specific components. Performance modification factors, expressing the probability of damage or impairment of a security element following the impact of a specific natural hazard, resulted comprised between 0.25 and 0.95, evidencing the potential severe impact of natural hazards on PPS. Overall, the results obtained contribute to the assessment and management of security risks in chemical sites, underscoring the need for holistic and synergic strategies to enhance security and safety towards the impact of natural hazards.