TY - JOUR T1 - Mayotte seismic crisis: building knowledge in near real-time by combining land and ocean-bottom seismometers, first results A1 - Saurel,Jean-Marie A1 - Jacques,Eric A1 - Aiken,Chastity A1 - Lemoine,Anne A1 - Retailleau,Lise A1 - Lavayssière,Aude A1 - Foix,Oceane A1 - Dofal,Anthony A1 - Laurent,Angèle A1 - Mercury,Nicolas A1 - Crawford,Wayne A1 - Lemarchand,Arnaud A1 - Daniel,Romuald A1 - Pelleau,Pascal A1 - de Berc,Maxime Bès A1 - Dectot,Grégoire A1 - Bertil,Didier A1 - Roullé,Agathe A1 - Broucke,Céleste A1 - Colombain,Alison A1 - Jund,Hélène A1 - Besançon,Simon A1 - Guyavarch,Pierre A1 - Kowalski,Philippe A1 - Roudaut,Mickael A1 - Apprioual,Ronan A1 - Battaglia,Jean A1 - Bodihar,Soumya A1 - Boissier,Patrice A1 - Bouin,Marie Paule A1 - Brunet,Christophe A1 - Canjamale,Kévin A1 - Catherine,Philippe A1 - Desfete,Nicolas A1 - Doubre,Cécile A1 - Dretzen,Rémi A1 - Dumouche,Tom A1 - Fernagu,Philippe A1 - Ferrazzini,Valérie A1 - Fontaine,Fabrice A1 - Gaillot,Arnaud A1 - Géli,Louis A1 - Griot,Cyprien A1 - Grunberg,Marc A1 - Guzel,Emre Can A1 - Hoste-Colomer,Roser A1 - Lambotte,Sophie A1 - Lauret,Frédéric A1 - Léger,Félix A1 - Maros,Emmanuel A1 - Peltier,Aline A1 - Vergne,Jérôme A1 - Satriano,Claudio A1 - Tronel,Frédéric A1 - Van Der Woerd,Jérôme A1 - Fouquet,Yves A1 - Jorry,Stephan A1 - Rinnert,Emmanuel A1 - Thinon,Isabelle A1 - Feuillet,Nathalie AD - Université de Paris, Institut de Physique du Globe de Paris, CNRS, F-75005 Paris, France AD - IFREMER, Centre de Bretagne, –Unité Géosciences Marines, 1625 Rte de Ste Anne, 29280 Plouzané, France AD - BRGM, French Geological Survey, Risk and Prevention Division, F- 45100 Orléans, France AD - Observatoire volcanologique du Piton de la Fournaise, Institut de Physique du Globe de Paris, F-97418 La Plaine des Cafres, La Réunion, France AD - Université de La Réunion, Laboratoire GéoSciences Réunion, F-97744 Saint Denis, La Réunion, France AD - ITES, Institut Terre Environnement de Strasbourg, UMR 7063, CNRS Université de Strasbourg, 5, rue René Descartes, 67084 Strasbourg AD - BRGM, French Geological Survey, Regional Division (Mayotte), F-97600 Mamoudzou, Mayotte, France AD - EOST, Université de Strasbourg/CNRS, 5 rue Descartes, 67084 Strasbourg Cedex, France AD - Université Clermont Auvergne, CNRS, IRD, OPGC, Laboratoire Magmas et Volcans, F-63000 Clermont-Ferrand, France AD - Istanbul Technical University, turkey AD - BRGM, French Geological Survey, Georesources, F-45100 Orléans, France UR - https://archimer.ifremer.fr/doc/00724/83604/ DO - 10.1093/gji/ggab392 KW - Indian Ocean KW - Volcano seismology KW - Volcano monitoring KW - Africa KW - Remote sensing of volcanoes N2 - The 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 days, 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 sub-marine 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 1D 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 5,000 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 10km offshore Mayotte eastern coastlines, is 20 to 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 km up to 25 km depth. The two clusters appear seismically separated, however our dataset is insufficient to firmly demonstrate this. Y1 - 2022/02 PB - Oxford University Press (OUP) JF - Geophysical Journal International SN - 0956-540X VL - 228 IS - 2 SP - 1281 EP - 1293 ID - 83604 ER -