A risk-based multi-level stress test methodology: application to six critical non-nuclear infrastructures in Europe

Recent natural disasters that seriously affected critical infrastructure (CI) with significant
socio-economic losses and impact revealed the need for the development of reliable meth-
odologies for vulnerability and risk assessment. In this paper, a risk-based multi-level stress
test method that has been recently proposed, aimed at enhancing procedures for evaluation
of the risk of critical non-nuclear infrastructure systems against natural hazards, is speci-
fied and applied to six key representative CIs in Europe, exposed to variant hazards. The
following CIs are considered: an oil refinery and petrochemical plant in Milazzo, Italy, a
conceptual alpine earth-fill dam in Switzerland, the Baku–Tbilisi–Ceyhan pipeline in Tur-
key, part of the Gasunie national gas storage and distribution network in the Netherlands,
the port infrastructure of Thessaloniki, Greece, and an industrial district in the region of
Tuscany, Italy. The six case studies are presented following the workflow of the stress test
framework comprised of four phases: pre-assessment phase, assessment phase, decision
phase and report phase. First, the goals, the method, the time frame and the appropriate
stress test level to apply are defined. Then, the stress test is performed at component and
system levels and the outcomes are checked and compared to risk acceptance criteria. A
stress test grade is assigned, and the global outcome is determined by employing a grading
system. Finally, critical components and events and risk mitigation strategies are formu-
lated and reported to stakeholders and authorities.