Rapid onset of mafic magmatism facilitated by volcanic edifice collapse

• Main Authors: Cassidy, M. (Author), Watt, S.F.L (Author), Talling, P.J (Author), Palmer, M.R (Author), Edmonds, M. (Author), Jutzeler, M. (Author), Wall-Palmer, D. (Author), Manga, M. (Author), Coussens, M. (Author), Gernon, T. (Author), Taylor, R.N (Author), Michalik, A. (Author), Inglis, E. (Author), Breitkreuz, C. (Author), Le Friant, A. (Author), Ishizuka, O. (Author), Boudon, G. (Author), McCanta, M.C (Author), Adachi, T. (Author), Hornbach, M.J (Author), Colas, S.L (Author), Endo, D. (Author), Fujinawa, A. (Author), Kataoka, K.S (Author), Maeno, F. (Author), Tamura, Y. (Author), Wang, F. (Author)
• Format: Article
• Language: English
• Published: 2015-06-28.
• Subjects: Article
• Online Access: Get fulltext

 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?km3) 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.