Why does institutional vulnerability matter? Perceptions of community members from the 2018 Montecito debris flows in California

As a result of California's housing and wildfire crisis, an increasing number of people live in areas likely to be impacted by natural hazards. Risk entails a combination of social, economic, physical, institutional, and environmental vulnerabilities. Previous studies of natural hazard vulnerability have focused primarily on social or physical vulnerability. We focus on institutional vulnerability, a neglected study area, to demonstrate the importance of assessing this dimension. We draw on the 2018 Montecito debris flow disaster in California and investigate how local institutions' actions aligned with the Priorities for Action from the Sendai Framework for Disaster Risk Reduction. While Montecito is a wealthy community with low social vulnerability, we found instances of high institutional vulnerability. As the memory of previous debris flows faded with time, local agencies could not accurately respond to the possibility of a debris flow recurrence. Conflicting institutional agendas and residents' expectations led to using a wildfire evacuation map instead of a debris flow map. An analysis of this institutional choice, based on a qualitative study that includes interviews with experts and community members, reveals that a more comprehensive assessment of natural hazard vulnerability, including institutional vulnerability, is critical. In addition, incorporating institutional vulnerability into the disaster risk reduction agenda will help to mitigate future risks and protect communities.