Evacuation choice before and after major debris flows: The case of Montecito, CA

Abstract

In 2018, a rare high magnitude debris-flows catastrophically impacted Montecito, resulting in human and material losses. Evacuations for rare natural hazards are complicated as residents have little or no experience with them. Therefore, understanding factors that influence evacuation choice for these rare debris-flows can help increase evacuation compliance and save lives. We employed mixed methods by using surveys and interviews. Data were collected after the disaster and addressed issues of evacuation behavior before and after the disaster. We employed Chi-squared, one-way Anova, and logistic regression to analyze the survey data, and we employed content analysis for the interviews. The evacuation choice did not significantly change before and after the disaster. Before the debris-flows, older respondents were more likely to evacuate. After, respondents who were worried about the debris-flows were more likely to evacuate. Residents who did not evacuate before and after the debris-flows based their decision on their home location and perceived risk. Before the debris-flows, impacted residents in the voluntary zone decided to remain due to the location of their residence (voluntary zone) and the influence of their social network. We recommend that municipalities carefully consider the type of natural hazard when defining evacuation zones and incorporate public awareness programs to educate and increase the risk perception of communities in hazardous areas, especially those threatened by rare natural hazards. In doing so, residents can rely on the knowledge learned from public awareness programs rather than their social network.