Indicator-based assessment of extreme threats (XTs) and their impacts on the resilience of geographical areas and critical infrastructures

The paper proposes an approach for anticipating and dealing with future extreme threats (x-threats or XTs, e.g., due to climate change) and threats challenging the resilience of the affected geographical areas and their infrastructures. The approach relies on a new composite indicator (CIRIX—Critical Infrastructure Resilience Index for X-threats) that combines indicators characterizing a particular XT and indicators characterizing the resilience of a given infrastructure to that XT. CIRIX, therefore, provides a threat- and infrastructure-specific measure of resilience for a given XT. We quantify the extremeness of XTs using a sub-hierarchy of indicators, including not only increased intensity but also increased complexity, increased impacts, and other characteristics. To illustrate the use of CIRIX for stress testing, we construct a synthetic but plausible XT scenario based on a historical event, the 2005 flooding in the Swiss city of Lucerne. We analyze it using CIRIX to investigate the resilience of the area’s most critical infrastructures. The threat-and-resilience assessments were performed using the ResilienceTool. The approach allows to (a) enhance preparedness for XTs, (b) perform “what-if” analyses (e.g., by varying values of threat or resilience indicators), (c) optimize resilience-related decisions, (d) stress test the resilience of critical infrastructures, and (e) potentially use the analysis results for insurance purposes (e.g., using CIRIX for parametric insurance).