Evidences of Plug Pressurization Enhancing Magma Fragmentation During the September 2016 Basaltic Eruption at Piton de la Fournaise (La Réunion Island, France)

During the September 2016 eruption of Piton de la Fournaise volcano on Réunion Island, a sudden shift from typical effusive activity to explosive ash and bomb emission occurred. This transition was linked to the pressurization of a degassed, cooled magma plug beneath a secondary vent (Vent B), which enhanced magma fragmentation. The study integrated geophysical data with textural and petrological analyses, revealing that the explosive phase involved denser, crystal-rich tephra (sideromelane and tachylite) alongside more gas-permeable, vesicular fragments (golden pumice and fluidal scoria). Permeability measurements and chemical analyses suggested that the sideromelane and tachylite components originated from subsurface crystallization of the initial magma types. This finding highlights the potential danger posed by such transitions in volcanic activity, particularly for tourist areas accustomed to 'gentle' eruptions.

Thivet, S., Gurioli, L., Di Muro, A., Derrien, A., Ferrazzini, V., Gouhier, M., Coppola, D., Galle, B., & Arellano, S. (2020). Evidences of Plug Pressurization Enhancing Magma Fragmentation During the September 2016 Basaltic Eruption at Piton de la Fournaise (La Réunion Island, France). Geochemistry, Geophysics, Geosystems, 21(2). Portico. https://doi.org/10.1029/2019gc008611