Cascading effects and cascading disasters are emerging fields of scientific research. The widespread diffusion of functional networks increases the complexity of interdependent systems and their vulnerability to large-scale disruptions. Although in recent years studies of interconnections and chain effects have improved significantly, cascading phenomena are often associated with the ''toppling domino metaphor'', or with high-impact, low-probability events. This paper aimed to support a paradigm shift in the state of the art by proposing a new theoretical approach to cascading events in terms of their root causes and lack of predictability. By means of interdisciplinary theory building, we demonstrate how cascades reflect the ways in which panarchies collapse. We suggest that the vulnerability of critical infrastructure may orientate the progress of events in relation to society's feedback loops, rather than merely being an effect of natural triggers. Our conclusions point to a paradigm shift in the preparedness phase that could include escalation points and social nodes, but that also reveals a brand new field of research for disaster scholars.

In recent years, there has been a gradual increase in research literature on the challenges of interconnected, compound, interacting, and cascading risks. These concepts are becoming ever more central to the resilience debate. They aggregate elements of climate change adaptation, critical infrastructure protection, and societal resilience in the face of complex, high-impact events. However, despite the potential of these concepts to link together diverse disciplines, scholars and practitioners need to avoid treating them in a superficial or ambiguous manner. Overlapping uses and definitions could generate confusion and lead to the duplication of research effort. This article gives an overview of the state of the art regarding compound, interconnected, interacting, and cascading risks. It is intended to help build a coherent basis for the implementation of the Sendai Framework for Disaster Risk Reduction (SFDRR). The main objective is to propose a holistic framework that highlights the complementarities of the four kinds of complex risk in a manner that is designed to support the work of researchers and policymakers. This article suggests how compound, interconnected, interacting, and cascading risks could be used, with little or no redundancy, as inputs to new analyses and decisional tools designed to support the implementation of the SFDRR. The findings can be used to improve policy recommendations and support tools for emergency and crisis management, such as scenario building and impact trees, thus contributing to the achievement of a system-wide approach to resilience.

The adoption of the European Floods Directive (2007/60/EC) represented a crucial improvement in the management of watercourses and coastlines. However, the beginning of a new phase of implementation requires the assessment of which emerging topics may be included in the review process. The aim of our research is to understand the existence of any legislative gaps that could limit the preparedness to cascading events and critical infrastructures breakdowns. First, we provide a review of the Floods Directive, the cascading phenomena and the vulnerability of critical infrastructures in the European legislation. Secondly, we analyse some case-studies to test the present approach and to improve the work of decision makers. Our results suggest that the Floods Directive tends to focus on localized flood impacts at smaller time scale and it could be ineffective to address the cross-scale impact of cascading events. Although some of the corrective actions may not be of competence of the Directive, we argue that their inclusion could limit uncertainties in the attribution of responsibilities and the coordination among different institutional levels.

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