Dynamic interdependencies: Problematising criticality assessment in the light of cascading effects

The paper connects two interrelated discourses: criticality assessments and cascading effects. During crises, crisis managers have to constantly assess and reassess the criticality of systems and elements in order to identify potential triggers for cascading effects and to distribute efficiently available resources for mitigation. To help practitioners to make the right decisions, models are needed for the preparation phase that extend their knowledge about dependency relations and critical system elements. To do so, the paper proposes a concept of dynamic interdependencies and criticality. It is argued that dependency relations and their impact on system elements are changing over time. We maintain that when elements and system either fail or become involved, or when resources become scarce and then regain availability, then the criticality of the individual element, the system, the resource, and finally the overall situation changes as well, either positively or negatively. This article also presents a software tool which models the dynamics of cascading crisis scenarios. Finally, this software is used to reconstruct an example of a cascading power failure to demonstrate how criticality evolves dynamically.