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Integrating timescales from diffusion modeling in crystals to geophysical monitoring data at a large submarine volcano (Fani Maoré, Mayotte)

Karoline Brückel 1, Etienne Médard1, Fidel Costa2, Lucia Gurioli1, Carole Berthod2, 3, Pauline Verdurme1, Jean-Christophe Komorowski2, Patrick Bachèlery1

  • Affiliations: 1Laboratoire Magmas et Volcans, Université Clermont Auvergne -- CNRS -- IRD, OPGC, Campus Universitaire des Cézeaux, Aubière, France. 2Université Paris Cité, Institut de Physique du Globe de Paris, CNRS, Paris, France. 3Observatoire volcanologique et sismologique de la Guadeloupe, Institut de Physique du Globe de Paris, Gourbeyre, France.

  • Presentation type: Poster

  • Presentation time: Monday 16:30 - 18:30, Room Poster Hall

  • Poster Board Number: 62

  • Programme No: 1.2.7

  • Theme 1 > Session 2

Abstract

A challenge of volcano monitoring is to link near-real-time observables, e.g. seismology, deformation, or gas emission, to deep magmatic processes, their variation over time and their relevance in eruption triggering. A key method to understand magmatic processes and their timescales with respect to eruption is to look at erupted products and apply diffusion geochronometry to zoned crystals. Thus, linking timescales from diffusion modeling to signs of unrest measured at Earth's surface has the potential to enhance eruption forecasting. The largest submarine eruption monitored to date that led to the birth of Fani Maoré (FM) volcano offshore Mayotte Island (Comoros Archipelago) is an excellent candidate to develop this approach. Multiple oceanographic cruises during this 2.5-year-long basanitic eruption (2018-2020) provide a unique multi-disciplinary dataset that can be used to better understand pre-eruptive magmatic processes. Reversely zoned olivine crystals in late erupted units suggest that basanitic magma interacted with a more evolved reservoir during ascent. Diffusion modeling in olivine, shows that this magma stalled below the second reservoir leading to progressively longer timescales of magma interaction as eruption continued -- from 1-3 months for the first flows, up to 17 months for later lava flows. Through regression analysis we can constrain the first magma interaction to April 2019. A year later, eruptive activity declined in March 2020. Both time periods are reflected by changes in seismic activity and a decline in deformation at FM, which suggests that the deep magmatic processes recorded by diffusion chronometry are recorded by monitoring parameters at the surface.