Ashley Bosa Dissertation Defense

Title: TRACKING NATURAL HAZARDS: BRIDGING RAIN-TRIGGERED LAHAR RESEARCH AND PROTECTIVE ACTION DECISION MAKING IN WILDLAND FIRE MANAGEMENT

Abstract: Understanding natural hazards is crucial for mitigating risks, protecting lives and property, and building resilience in communities. By enabling communities to prepare, respond effectively, and take protective action against disasters, the devastating impacts of natural hazards can be significantly reduced. However, transitioning from research to tangible community impact involves a multi-step process that bridges the gap between scientific knowledge and practical application. In this dissertation, I present two seismo-acoustic analyses of multiple rain-triggered lahar events at Volcán de Fuego in Guatemala, a granulometry study that attempts drone imagery analysis for lahar deposits, and a case-study review of the roles of emergency managers and decision makers and message dissemination within the framework of the Chains of Events model in natural hazard evacuations. With the empirical, physical monitoring of lahars, I quantify the speed of lahars and multiple pulses, or surges, in the flow. I also use time-lapse imagery to measure stage of the flows and correlate stage fluxes with power proxies in the seismo-acoustic signals as a method of determining the destructive potential of volcanic mudflows. The primary goal of the lahar research is to develop geophysical monitoring methods that enable remote and real-time estimation of evolving flow parameters in channels around Fuego, with application to other volcanoes. The final chapter of my dissertation addresses knowledge gaps in how decision makers handle uncertainty and information during high impact wildfire scenarios and how this leads to evacuation decisions. In the case-study chapter, I use wildfire evacuations and messaging as a basis to conduct semi-structured interviews of city and county emergency managers. This work explores the critical support emergency managers offer before and during wildfire crises, and how their roles impact evacuation decision-making within the context of Chains of Events.  Given the diverse objectives in this dissertation, the insights gained can be applied to a broad range of natural hazards, enhancing not only our understanding of how we monitor real-time hazards, but also how decision-makers use information to execute evacuation orders. By leveraging more practical applications between researchers and community stakeholders, we can develop more effective real-world applications that strengthen community resilience when faced with future natural disaster events.

Advisor: Brittany Brand

Committee: Dr. Jen Pierce, Dr. Greg Waite, Dr. Thomas Pierson, Dr. Michael Lindell