Intellectual merit: The 79 AD eruption of Vesuvius, which destroyed Pompeii and Herculaneum, is generally regarded as the 'type' example of Plinian volcanism. This eruption is very well documented, and it occurred at the most dangerous of the world's Decade Volcanoes where at least 600,000 people live within 10 km of the crater. The sustained explosive eruptions, which characterize Vesuvius' history, are highly destructive events where stable eruption plumes give way to column collapse, and/or phreatomagmatism. In this context, the 79AD eruption can be considered as a "case study" or "field laboratory" for understanding such complex changes in eruption processes. Although much is known about the physical characteristics and chemistry of its deposits, many questions remain regarding the eruptions themselves: 1. What was the cause of sudden early column collapse (prior to the onset of phreatomagmatism), which generated the first pyroclastic density currents (PDCs), responsible for destruction and deaths at Herculaneum and surrounding areas? 2. What were the conditions of ascent and vesiculation of magma during the late, phreatomagmatic phase of the eruptions characterized by highly unstable plumes? 3. What influence did microlites in these melts, mainly leucites, have on eruption dynamics, crystallization kinetics and magma rheology? Answers to these questions will provide a more complete understanding of complex changes in eruption dynamics and style. Data sets for vesicle and microlite size, density and shape will be determined and compared with experimental data to constrain timing and rates of leucite crystallization and vesicle formation. Experiments on leucite crystallization will be conducted at UAF where studies are already underway on vesicle development [EAR 0511070]).
Broader impacts: By focusing on this well-constrained and famous historical eruption, the proposed work should have broad interest to the public and application to other volcanological investigations. Students and PIs will benefit from the cross-institutional and international exchange of expertise and ideas between UH, UAF, UO and University of Cagliari - ensuring the exchange of ideas and approaches among individuals with a variety of cultural and societal backgrounds. Results will be incorporated into teaching materials for Hawaiian and Alaskan students, and the budget includes funds to ensure the direct involvement of students in the research. Further outreach will be achieved through an educational web-page which uses the 79AD example to demonstrate geological processes through analogy with this fascinating and famous eruption to high school students. Concurrently, results will be incorporated into education and hazard communication to officials of the Italian Civil Defense plan for Vesuvius.
