High impact low probability events: research landscape and future opportunities

Abstract High-impact, low-probability (HILP) events, characterised by their extreme consequences and inherent unpredictability, pose a growing challenge to disaster risk reduction in an era of systemic and cascading crises. Traditional risk assessment frameworks, which rely on probability-based models, often fail to capture the full scope of these events, leaving critical vulnerabilities unaddressed. This semi-systematic state-of-the-art review synthesizes current academic discourse on HILPs to identify their defining characteristics and implications for disaster preparedness and response. We analyse a dataset of 109 papers, highlighting the limitations of conventional planning tools and emphasising the need for adaptive, forward-looking strategies that integrate scenario planning, stress testing, and resilience assessment. The review finds that while HILPs are increasingly recognised in national risk registers and post-disaster response frameworks, their integration into preparedness, training, and governance systems remains limited. A key gap lies in translating theoretical insights into operational strategies that can be deployed before crises occur. The paper advocates for a hazard-agnostic, interdisciplinary approach that bridges risk and resilience thinking, enabling systems to anticipate, absorb, and adapt to a broad spectrum of threats. By advancing a research agenda beyond the Sendai Framework, this review contributes to a more robust understanding of HILPs and supports the development of more resilient and responsive disaster management systems.