Mayotte seismic crisis: building knowledge in near real-time by combining land and ocean-bottom seismometers, first results
Type | Article | ||||||||||||
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Date | 2022-02 | ||||||||||||
Language | English | ||||||||||||
Author(s) | Saurel Jean-Marie![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
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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 |
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Source | Geophysical Journal International (0956-540X) (Oxford University Press (OUP)), 2022-02 , Vol. 228 , N. 2 , P. 1281-1293 | ||||||||||||
DOI | 10.1093/gji/ggab392 | ||||||||||||
WOS© Times Cited | 5 | ||||||||||||
Keyword(s) | Indian Ocean, Volcano seismology, Volcano monitoring, Africa, Remote sensing of volcanoes | ||||||||||||
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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