SGER: 1998 Volcan Casita Mudflow, Nicaragua

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9901694SheridanThis SGER award is aimed at rapid response placement of a volcanologist on site at one of the worst volcano-related disasters of the decade. Torrential rains associated with hurricane Harold filled the summit crater of Volcan Casita, Nicaragua apparently leading to rapid overflow through a breach in the crater wall. The resulting avalanche of water-saturated volcanic debris swept down the mountain enveloping several villages. Volcanic mudflows (lahars) such as this pose major hazards to populations throughout the world, yet details regarding the triggering mechanism(s), flow characteristics, and material properties generally only are available from pre-historic or ancient deposits. An approximate one-week field campaign, in collaboration with the Geophysical Institute of the University of Nicaragua, will focus on measurements and sampling of fresh lahar deposits, collection of eye-witness accounts of the initiation and flow, and aerial observations of the source area and outflow pattern. Samples and other data will be evaluated upon return from the field, and these data will be used to construct a model for the inception of the Volcan Casita mudflow. The primary data and observations, together with the derived model, will contribute to a better understanding of the mechanisms leading to lahar formation and emplacement, and will assist in assessing and mitigating the risks associated with these phenomena in other regions.