Cascading hazards and compound disasters

Abstract

T he twenty-first century has ushered in an era of unprecedented global interdependence. Environmental degradation , climate change, rapid urbanization, poverty, technological systems, and geopolitical volatility now intersect in ways that reshape the production, amplification, and consequences of disaster risk. Disasters are no longer defined by natural extremes; instead, they are increasingly the product of complex interactions among multiple hazards, entrenched social vulnerabilities, and systemic gov-ernance failures. In this context, traditional hazard-based approaches to disaster risk management have proven insufficient. The linear models that once guided preparedness and response are being superseded by a recognition that disasters emerge from the convergence of interdependent systems-ecological, infrastructural, socioeconomic , and institutional. The growing prevalence of cascading hazards and compound disasters underscores the need for a more comprehensive and integrated understanding of risk. This special issue of npj Natural Hazards contributes to this critical reorientation by assembling seven original studies that interrogate how systemic risks unfold, interact, and escalate in diverse geographic and institutional contexts. These include: a theoretical reframing of earthquake disaster causality 1 ; geomorphic feedbacks in flood-prone mountain systems 2 ; regional debris flow patterns and emerging climate influences 3 ; compound drought-heatwave-driven regimes that exacerbate fires in South America 4 ; compound drought-heatwave effects on agriculture in Mexico 5 ; postfire debris-flow rainfall impacts in the U.S. Southwest 6 ; and the infrastructural collapse during Libya's Derna dam failure 7. These contributions span a range of domains-from geomorphology and climate science to agriculture, infrastructure, and disaster governance, offering a unique perspective on the complex and interconnected nature of contemporary disasters. This editorial aims to synthesize the insights offered by the collection by framing each paper within a systemic risk paradigm. In doing so, it highlights how the age of global interdependence demands new methodologies, governance archi-tectures, and normative commitments to build resilience and avoid preventable disasters. Conceptual foundations: disasters as avoidable failures At the conceptual core of the collection lies the contribution "Earthquakes yes, disasters no," 1 which provides a clear and forceful argument: while earthquakes are inevitable geophysical phenomena, disasters are not. The paper dismantles the widespread misconception that natural hazards inevitably lead to catastrophe by demonstrating that human decisions, govern-ance failures, and social vulnerability significantly shape disaster outcomes. Exposure, inadequate infrastructure, and a lack of preparedness, rather than the seismic event itself, are what transform a hazard into a catastrophe. A comprehensive analysis, along with other case studies, underscores that the consequences of earthquakes are significantly influenced by the level of societal vulnerability and the capacity of communities and institutions to respond and adapt effectively 1. Inadequate planning, negligence , and insufficient political commitment are primary factors that exacerbate the occurrence of disasters. Thus, it is imperative to acknowledge the critical importance of seismic risk assessment, public awareness initiatives, resilient construction practices, and efficient communication as fundamental strategies for mitigating future losses. The analysis also highlights the importance of earthquake-triggered cascading hazards-such as tsunamis, landslides, fires, and technological failures-as a critical area of concern in seismic risk assessment 1. These interactions complicate emergency response and can magnify disaster impacts far beyond the initial shock. In light of this, there is a pressing need for a comprehensive and integrated risk assessment that synergizes geophysical science , engineering principles, and social insights. Such an approach will enhance our ability to anticipate and effectively manage the risks associated with earthquakes. By asserting that disasters are the result of preventable societal conditions, "Earthquakes yes, disasters no" provides a foundational lens through which to understand the broader contributions in this collection. It offers a reminder that risk is not only a technical issue but a deeply political one, and that disaster prevention begins long before the ground starts to shake 1. Cascading geomorphic hazards in mountain systems Mountain systems exemplify the systemic character of contemporary disaster risk. Their steep topography, ecological sensitivity, and climatic exposure make them hotspots for hazard interactions and cascading effects. Two contributions in this issue 2,3 shed light on how geomorphic and cryosphere processes interact to create multi-scalar risks in mountainous terrain. The aftermath of an extreme precipitation event in Colorado, USA is analyzed, with particular emphasis on the dynamic interactions between landslides and river channel morphology. The findings indicate that landslides triggered during peak flood discharge not only contribute sediment to downstream areas but also initiate substantial channel widening and heightened flood vulnerability 2. This case study illustrates that landslide-channel interactions can substantially amplify channel widening and flood risk, thereby underscoring the necessity for sustained monitoring and flood hazard management strategies. A regional inventory of debris flows has been developed for the northern Tien Shan region of Central Asia. This inventory emphasizes the escalating influence of climate-sensitive cryo-sphere processes, such as glacial lake outburst floods and intense glacier and snowmelt. The analysis indicates that GLOF-related debris flows peaked in the 1970s and declined thereafter, while pluvial debris flows show no clear long-term trend but are increasingly observed at higher elevations 3. This trend introduces significant challenges for transboundary hazard governance in a region characterized by political fragmentation. These studies converge on a key insight: mountain hazards are not merely physical phenomena , but systemic disruptions embedded in ecological feedbacks, climate trajectories, and governance gaps. Effective risk reduction in such settings requires real-time data, cross-border coordination, and governance systems that are responsive to feedback and complexity.