Rapid onset of mafic magmatism facilitated by volcanic edifice collapse

Abstract : Volcanic edifice collapses generate some of Earth's largest landslides. How such unloading affects the magma storage systems is important for both hazard assessment and for determining long-term controls on volcano growth and decay. Here we present a detailed stratigraphic and petrological analyses of volcanic landslide and eruption deposits offshore Montserrat, in a subduction zone setting, sampled during Integrated Ocean Drilling Program Expedition 340. A large (6-10 km 3) collapse of the Soufrière Hills Volcano at ~130 ka was followed by explosive basaltic volcanism and the formation of a new basaltic volcanic center, the South Soufrière Hills, estimated to have initiated <100 years after collapse. This basaltic volcanism was a sharp departure from the andesitic volcanism that characterized Soufrière Hills' activity before the collapse. Mineral-melt thermobarometry demonstrates that the basaltic magma's transit through the crust was rapid and from midcrustal depths. We suggest that this rapid ascent was promoted by unloading following collapse.
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M. Cassidy, S Watt, P. Talling, M. Palmer, M. Edmonds, et al.. Rapid onset of mafic magmatism facilitated by volcanic edifice collapse. Geophysical Research Letters, American Geophysical Union, 2015, 42 (12), pp.4778-4785. ⟨10.1002/2015gl064519⟩. ⟨insu-01892585⟩

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