Quantifying the compounding effects of natural hazard events: a case study on wildfires and floods in California

Abstract Compounding weather events occur when two or more weather hazards combine to produce societal or environmental impacts. Despite the potentially catastrophic damage these hazards can cause to critical infrastructure, the quantification of such compounding hazards lags behind. This study presents a new method for analyzing how consecutive severe weather events interact and compound damage over time. The framework examines whether initial events amplify the impact of subsequent disasters, using flexible lag identification to determine optimal recovery periods. Applied to California wildfires and subsequent floods, it reveals regional variations in compounding effects and their temporal evolution. By quantifying these compounding hazards, this methodology provides crucial insights for policy makers and resilience managers to address climate change risks and the dynamic nature of compounding hazards. While developed for California, this approach can be applied globally to assess compounding hazards and inform disaster preparation strategies.