Rapid onset of mafic magmatism facilitated by volcanic edifice collapse

M. Cassidy (1, 2) , S F L Watt (1, 3) , P. J. Talling (4) , M. R Palmer , M. Edmonds , M. Jutzeler , D. Wall-Palmer (5) , M. Manga , M. Coussens , T. Gernon , R. N Taylor , A. Michalik , E. Inglis , C. Breitkreuz , A. Le Friant (6) , O. Ishizuka (7) , G. Boudon (6) , M. Mccanta (8) , T. Adachi , M. Hornbach , S. L Colas (6) , D. Endo (9) , A. Fujinawa , K. S Kataoka , F. Maeno , Y. Tamura , F. Wang

1 University of Southampton
2 JGU - Johannes Gutenberg - Universität Mainz = Johannes Gutenberg University
3 School of Geography, Earth and Environmental Sciences [Birmingham]
4 NOC - National Oceanography Centre
5 SoGEES - School of Geography, Earth and Environmental Sciences [Plymouth]
6 IPGP - Institut de Physique du Globe de Paris
7 AIST - National Institute of Advanced Industrial Science and Technology
8 Tufts University [Medford]
9 Université de Tsukuba = University of Tsukuba

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.

Domaines: Volcanologie

M. Cassidy, S F L Watt, P. J. Talling, M. R Palmer, M. Edmonds, et al.. Rapid onset of mafic magmatism facilitated by volcanic edifice collapse. Geophysical Research Letters, 2015, 42 (12), pp.4778-4785. ⟨10.1002/2015gl064519⟩. ⟨insu-01892585⟩