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Insights on magma dynamics from integrated observational, experimental, and numerical methods

Janine Birnbaum1

Abstract

Observations of volcanic eruptions are our primary source of information on the dynamics of magmatic systems. However, interpretation of the complex reality requires experiments using analogue or natural materials. Numerical models can bridge the temporal and spatial scales of experiments and the Earth, and identify dynamic regimes and controlling processes. Each of these sources are powerful individually, but genuine integration of these methods leads to deeper insight. Here, we use numerical models to plan and interpret high-temperature vesiculation experiments on natural obsidian at a range of spatial scales (5 mm to 18 cm diameter) and reveal the role of shear on promoting bubble connectivity and resisting bubble growth. Joint numerical simulations of water content and speciation, CO2 concentration, and vesicle abundance and texture compared with natural samples recovered during drilling of the IDDP-1 borehole reveal in unprecedented detail the response of magma to induced decompression and cooling. Calibration of the numerical models on confined vesiculation experiments, small and large, and on natural samples with a controlled pressure-temperature history, improves our confidence in modeling meter-scale volcanic conduits. We discuss opportunities for and the importance of synergistic multi-methodological studies in understanding complex volcanic processes.