1. Mayotte seismic crisis: building knowledge in near real-time by combining land and ocean-bottom seismometers, first results
- Author
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Jérôme Vergne, Jean Battaglia, Louis Géli, Stephan J. Jorry, Jérôme Van der Woerd, Anthony Dofal, Jean-Marie Saurel, Hélène Jund, Marie Paule Bouin, Arnaud Gaillot, Alison Colombain, Ronan Apprioual, Nicolas Mercury, Sophie Lambotte, Valérie Ferrazzini, Cécile Doubre, Yves Fouquet, Philippe Kowalski, Simon Besançon, Océane Foix, Cyprien Griot, Céleste Broucke, Mickaël Roudaut, Claudio Satriano, Grégoire Dectot, Isabelle Thinon, Rémi Dretzen, Lise Retailleau, Tom Dumouche, Nicolas Desfete, Félix Léger, Pierre Guyavarch, Didier Bertil, Aude Lavayssière, Philippe Fernagu, Aline Peltier, Fabrice R. Fontaine, Frédéric Lauret, Arnaud Lemarchand, Emmanuel Rinnert, Chastity Aiken, Pascal Pelleau, Wayne C Crawford, Marc Grunberg, Frédéric Tronel, Roser Hoste-Colomer, Soumya Bodihar, Emmanuel Maros, Christophe Brunet, R. Daniel, Eric Jacques, Kevin Canjamale, Emre Güzel, Patrice Boissier, Anne Lemoine, Agathe Roullé, Philippe Catherine, Maxime Bes de Berc, Nathalie Feuillet, Angèle Laurent, Institut Terre Environnement Strasbourg (ITES), École Nationale du Génie de l'Eau et de l'Environnement de Strasbourg (ENGEES)-Université de Strasbourg (UNISTRA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique du Globe de Paris (IPGP (UMR_7154)), Institut national des sciences de l'Univers (INSU - CNRS)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), Observatoire Volcanologique du Piton de la Fournaise (OVPF), Institut de Physique du Globe de Paris (IPG Paris), Laboratoire GéoSciences Réunion (LGSR), Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris), Ecole et Observatoire des Sciences de la Terre (EOST), Université de Strasbourg (UNISTRA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Institut de Recherche pour le Développement et la société-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA), Faculty of Electrical and Electronics Engineering [Istanbul], and Istanbul Technical University (ITÜ)
- Subjects
Volcano monitoring ,Seismometer ,010504 meteorology & atmospheric sciences ,Population ,Magnitude (mathematics) ,Context (language use) ,Induced seismicity ,010502 geochemistry & geophysics ,01 natural sciences ,Remote sensing of volcanoes ,Geochemistry and Petrology ,education ,Indian Ocean ,0105 earth and related environmental sciences ,[SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics ,education.field_of_study ,geography ,geography.geographical_feature_category ,Volcano seismology ,Geophysics ,Volcano ,Africa ,Submarine pipeline ,Geology ,Seismology ,Channel (geography) - Abstract
SUMMARYThe brutal onset of seismicity offshore Mayotte island North of the Mozambique Channel, Indian Ocean, that occurred in May 2018 caught the population, authorities and scientific community off guard. Around 20 potentially felt earthquakes were recorded in the first 5 d, up to magnitude Mw 5.9. The scientific community had little pre-existing knowledge of the seismic activity in the region due to poor seismic network coverage. During 2018 and 2019, the MAYOBS/REVOSIMA seismology group was progressively built between four French research institutions to improve instrumentation and data sets to monitor what we know now as an on-going exceptional submarine basaltic eruption. After the addition of 3 medium-band stations on Mayotte island and 1 on Grande Glorieuse island in early 2019, the data recovered from the Ocean Bottom Seismometers were regularly processed by the group to improve the location of the earthquakes detected daily by the land network. We first built a new local 1-D velocity model and established specific data processing procedures. The local 1.66 low VP/VS ratio we estimated is compatible with a volcanic island context. We manually picked about 125 000 P and S phases on land and sea bottom stations to locate more than 5000 events between February 2019 and May 2020. The earthquakes outline two separate seismic clusters offshore that we named Proximal and Distal. The Proximal cluster, located 10 km offshore Mayotte eastern coastlines, is 20–50 km deep and has a cylindrical shape. The Distal cluster start 5 km to the east of the Proximal cluster and extends below Mayotte's new volcanic edifice, from 50 to 25 km depth. The two clusters appear seismically separated, however our data set is insufficient to firmly demonstrate this.
- Published
- 2021