Integrated Petrologic and Volcanologic Studies of the 1991 Eruption of Hudson Volcano

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CareyEAR 0337023 The 1991 eruption of Hudson volcano in Chile was one of the largest explosive events of the twentieth century with a Volcanic Explosivity Index (VEI) of 5. The eruption transected a thick glacier in the summit caldera resulting in significant magma/water interactions. The objectives of the work will be to investigate the relationship between the different magma compositions erupted in 1991 (basalt, trachyandesite and rhyolite) and define the pressure, temperature and volatile conditions of the magmatic system prior to eruption. In order to investigate potential modes of fragmentation, particle morphologies will be quantitatively characterized using fractal analysis and vesicularity indices. Measurements of grain size and dispersal characteristics will be used in conjunction with observations of eruption column height to evaluate the effectiveness of theoretical models for tephra dispersal that are often used to reconstruct the dynamics of ancient eruptions. The overall project is intended to 1) provide a more detailed understanding of the volcanological processes of the 1991 Hudson eruption, 2) examine the potential effects of glacial meltwater on the eruption, 3) develop a model for the magmatic system beneath Hudson based on the petrologic and geochemical features of the erupted products and 4) test existing tephra fallout models. In terms of broader impacts, the project will involve the participation of graduate students in both the United States and Argentina and will thus serve as a valuable exchange experience. In addition, an important objective will be to foster more interest in volcanological research in Argentina through this collaborative research. The P.I.s will share the information gained at Hudson to the general public via a website constructed to highlight the history, activity, and hazards associated with this volcano. Research results will also be integrated into undergraduate and graduate courses taught by the P.I.s at their respective institutions.