Harnessing Global Evidence to Improve Multi-Hazard Risk Management Through Forensic Analysis

Natural hazards interact in time and space, creating multi-hazards, yet our understanding of how these interactions translate into societal impact and challenge existing risk management efforts remains fragmented. Recent evidence demonstrates that multi-hazard events (including comprising compound, consecutive, and a combination thereof) often result in disproportionately high impacts compared to single events. Despite the growing recognition of these complex risks, real-world examples repeatedly highlight critical gaps in disaster risk management, where siloed approaches fail to address the cascading dynamics of interacting hazards. As the world transitions into a regime of more frequent and simultaneous climate-related extremes, there is an urgent need to empirically understand these management challenges to move beyond static, single-hazard assessments. 

To address this gap, we present a disaster forensics analysis of a first-of-its-kind global dataset comprising close to 60 multi-hazard events that occurred across diverse geographical and socioeconomic contexts between 1980 and 2023. Using a standardized method, we characterized the spatiotemporal interactions of hazards, exposures, and vulnerabilities to identify the specific mechanisms that amplify impacts and complicate management responses. 

Our analysis shows that the impacts of multi-hazard events are systematically amplified through five distinct pathways, each presenting unique challenges for risk managers: 

• Physical Amplification: Where one hazard alters the environment (e.g., ground saturation or structural damage) to intensify the severity of a subsequent hazard. 

• Capacity Overload: Where overlapping or successive events compress response timelines, overwhelming institutional and logistical capacities. 

• Cascading Impacts: Where disruptions propagate across interconnected systems, creating systemic risks that single-sector management cannot contain. 

• Vulnerability Amplification: Where an initial hazard intensifies existing social, economic, or political fragilities, making systems more susceptible to future shocks. 

• Incomplete Recovery: Where subsequent hazards strike before reconstruction is finalized, deepening losses and extending disruption. 

Finally, our findings challenge the traditional view of vulnerability as a static condition. We demonstrate that vulnerability is dynamic, evolving rapidly through spatiotemporal interactions and societal shocks. We identify a "cycle of risk" particularly prevalent in vulnerable contexts, where consecutive shocks trap communities in a loop of incomplete recovery. These insights provide a blueprint for the next generation of risk management: strategies must shift from reactive, single-hazard responses to proactive approaches that explicitly account for these amplification pathways and the dynamic evolution of vulnerability.