"Silicic magma chambers, explosive volcanism, and a remarkable tectonic control on the ""Earth System"""

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I propose a program in three distinct research areas. The first two share a common theme that is explosive volcanism and are motivated by two questions: 1) Why do volcanoes and magma chambers erupt explosively? and, 2) Are there rigorous and reliable ways to forecast volcanism that is dangerous to humans? From an observational perspective, a crucial step towards addressing the first question is to characterize the long-term behavior of magmatic systems that have a history of volcanic activity. A roadblock to building and understanding such a data set, however, is that these systems evolve over million year time scales. Thus, key time series data must be uniquely inferred from textural and chemical data preserved in fossil magma chambers and prehistoric pyroclastic deposits, which is challenging. To this end, we develop a rigorous field- and mineral chemistry-based methodology that enables us to identify key magmatic processes in geological data, as well as their evolution prior to eruption. To address the second question, we turn to real-time observations of pre-eruptive seismic tremors. We extend our preliminary model that predicts the character of this oscillation prior to dangerous eruptions to make testable predictions also for tremor amplitude and related effects such as magmatic gas flux and ground deformation. This work will provide a new reliable tool for forecasting explosive eruptions. The third research area explores provocative implications of a remarkable prediction that the mantle thermal regime during supercontinental cycles will cause basalt crustal production to virtually cease. Extensive hydration of mantle (rather than crustal) rocks will, in turn, produce massive fluxes of methane and hydrogen into the deep ocean. This work proposes a fundamental tectonic control on the long-term variability of the chemistry and biology of the oceans, as well as on surface climate.