Leveraging network theory and stress tests to assess interdependencies in critical infrastructures

Abstract

Many modern critical infrastructures manifest reciprocal dependencies at various levels and on a time-evolving scale. Network theory has been exploited in the last decades to achieve a better understanding of topologies, correlations and propagation paths in case of perturbations. The discipline is providing interesting insights into aspects such as fragility and robustness of different network layouts against various types of threats, despite the difficulties arising in the modeling of the associated processes and entity relationships. Indeed, the evolution of infrastructures is not, in general, the straightforward outcome of a comprehensive a priori design. Rather, factors such as societal priorities, technical and budgetary constraints, critical events and the quest for better and cost-effective services induce a continuous change, while new kinds of interdependencies emerge. As a consequence, mapping emerging behavior can constitute a challenge and promote the development of innovative approaches to analysis and management. Among them, stress tests are entering the stage in order to assess networked infrastructures and reveal the associated operational boundaries and risk exposures. In this chapter, we first overview key developments of network science and its applications to primary infrastructure sectors. Secondly, we address the implementation of network-theoretical concepts in actions related to resilience enhancement, referring in particular to the case of stress tests in the banking sector. Finally, a discussion on the relevance of those concepts to critical infrastructure governance is provided.