Mayotte seismic crisis: building knowledge in near real-time by combining land and ocean-bottom seismometers, first results

Type Article
Date 2021-02
Language English
Author(s) Saurel Jean-MarieORCID1, Jacques Eric1, Aiken ChastityORCID2, Lemoine AnneORCID3, Retailleau Lise1, 4, Lavayssière Aude1, Foix Oceane2, Dofal AnthonyORCID1, 5, Laurent Angèle1, Mercury Nicolas3, 6, Crawford Wayne1, Lemarchand Arnaud1, Daniel Romuald1, Pelleau Pascal2, de Berc Maxime Bès6, Dectot Grégoire7, Bertil Didier3, Roullé Agathe3, Broucke Céleste8, Colombain Alison3, Jund Hélène8, Besançon Simon1, Guyavarch Pierre2, Kowalski Philippe1, 4, Roudaut Mickael2, Apprioual Ronan2, Battaglia Jean9, Bodihar Soumya1, Boissier Patrice1, 4, Bouin Marie Paule1, Brunet Christophe1, 4, Canjamale Kévin1, 4, Catherine Philippe1, 4, Desfete Nicolas1, 4, Doubre Cécile6, Dretzen Rémi8, Dumouche Tom1, Fernagu Philippe2, Ferrazzini Valérie1, 4, Fontaine Fabrice1, 5, Gaillot Arnaud2, Géli Louis2, Griot Cyprien1, 4, Grunberg Marc8, Guzel Emre Can10, Hoste-Colomer Roser3, Lambotte Sophie6, Lauret Frédéric1, 4, Léger Félix1, Maros Emmanuel2, Peltier Aline1, 4, Vergne Jérôme8, Satriano Claudio1, Tronel Frédéric7, Van Der Woerd Jérôme6, Fouquet Yves2, Jorry Stephan2, Rinnert Emmanuel2, Thinon Isabelle11, Feuillet Nathalie1
Affiliation(s) 1 : Université de Paris, Institut de Physique du Globe de Paris, CNRS, F-75005 Paris, France
2 : IFREMER, Centre de Bretagne, –Unité Géosciences Marines, 1625 Rte de Ste Anne, 29280 Plouzané, France
3 : BRGM, French Geological Survey, Risk and Prevention Division, F- 45100 Orléans, France
4 : Observatoire volcanologique du Piton de la Fournaise, Institut de Physique du Globe de Paris, F-97418 La Plaine des Cafres, La Réunion, France
5 : Université de La Réunion, Laboratoire GéoSciences Réunion, F-97744 Saint Denis, La Réunion, France
6 : ITES, Institut Terre Environnement de Strasbourg, UMR 7063, CNRS Université de Strasbourg, 5, rue René Descartes, 67084 Strasbourg
7 : BRGM, French Geological Survey, Regional Division (Mayotte), F-97600 Mamoudzou, Mayotte, France
8 : EOST, Université de Strasbourg/CNRS, 5 rue Descartes, 67084 Strasbourg Cedex, France
9 : Université Clermont Auvergne, CNRS, IRD, OPGC, Laboratoire Magmas et Volcans, F-63000 Clermont-Ferrand, France
10 : Istanbul Technical University, turkey
11 : BRGM, French Geological Survey, Georesources, F-45100 Orléans, France
Source Geophysical Journal International (0956-540X) (Oxford University Press (OUP)), 2021-02 , Vol. 228 , N. 2 , P. 1281-1293
DOI 10.1093/gji/ggab392
Keyword(s) Volcano seismology, Volcano monitoring, Submarine volcanic eruption, Indian Ocean, Mayotte
Abstract

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.

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Saurel Jean-Marie, Jacques Eric, Aiken Chastity, Lemoine Anne, Retailleau Lise, Lavayssière Aude, Foix Oceane, Dofal Anthony, Laurent Angèle, Mercury Nicolas, Crawford Wayne, Lemarchand Arnaud, Daniel Romuald, Pelleau Pascal, de Berc Maxime Bès, Dectot Grégoire, Bertil Didier, Roullé Agathe, Broucke Céleste, Colombain Alison, Jund Hélène, Besançon Simon, Guyavarch Pierre, Kowalski Philippe, Roudaut Mickael, Apprioual Ronan, Battaglia Jean, Bodihar Soumya, Boissier Patrice, Bouin Marie Paule, Brunet Christophe, Canjamale Kévin, Catherine Philippe, Desfete Nicolas, Doubre Cécile, Dretzen Rémi, Dumouche Tom, Fernagu Philippe, Ferrazzini Valérie, Fontaine Fabrice, Gaillot Arnaud, Géli Louis, Griot Cyprien, Grunberg Marc, Guzel Emre Can, Hoste-Colomer Roser, Lambotte Sophie, Lauret Frédéric, Léger Félix, Maros Emmanuel, Peltier Aline, Vergne Jérôme, Satriano Claudio, Tronel Frédéric, Van Der Woerd Jérôme, Fouquet Yves, Jorry Stephan, Rinnert Emmanuel, Thinon Isabelle, Feuillet Nathalie (2021). Mayotte seismic crisis: building knowledge in near real-time by combining land and ocean-bottom seismometers, first results. Geophysical Journal International, 228(2), 1281-1293. Publisher's official version : https://doi.org/10.1093/gji/ggab392 , Open Access version : https://archimer.ifremer.fr/doc/00724/83604/