The unexpected Mayotte 2018–2020 seismic sequence: a reappraisal of the regional seismicity of the Comoros

Type Article
Date 2021
Language English
Author(s) Bertil Didier1, Mercury Nicolas1, 2, Doubre Cécile2, Lemoine Anne1, Van Der Woerd Jérôme2
Affiliation(s) 1 : BRGM, Department of Risks and Prevention, 3 av. Claude-Guillemin - BP 36009, 45060 Orléans Cedex 2, France
2 : Institut Terre Environnement de Strasbourg, UMR 7063 Université de Strasbourg, CNRS, 5 rue René Descartes, 67084 Strasbourg Cedex, France
Source Comptes Rendus. Géoscience (1778-7025) (Cellule MathDoc/CEDRAM), 2021 , Vol. 353 , N. S1 , P. 1-25
DOI 10.5802/crgeos.79
Keyword(s) Seismicity, Seismo-volcanic hazard, Comoros, Mayotte, Mozambique Channel.

TheMayotte seismic sequence that started on 10May 2018, with a main shock of magnitude Mw 5.9 on May 15, followed by a major offshore volcanic activity, raises several questions of seismovolcanic hazards in the Comoros region. The unexpected size and duration of the crisis is an opportunity to reassess the distribution and magnitude of the seismicity near Mayotte Island, but also regionally. We present a comprehensive seismicity catalogue of the region including the Mozambique Channel, the Mozambique coast and Madagascar, based partly on previously published data in the region and partly on unpublished data from local catalogues for the Comoros and Madagascar. Our catalogue extends from 1900 onward with a completeness of magnitude 5.5 until 1980s and decreasing only recently to 4.5 after 2010. It comprises the events of magnitude Mlv ¸3.5 for the seismic sequence of Mayotte from May 2018 to October 2020 as the crisis is still ongoing. Present knowledge of the seismicity, largely partial in distribution and magnitude before 1980, makes the seismic sequence of 2018–2020 an exceptional and unprecedented seismo-volcanic event in the region. We discuss the distribution of seismicity in time and space within the context of the south eastward propagation of the East African rift system towards Madagascar.

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Bertil Didier, Mercury Nicolas, Doubre Cécile, Lemoine Anne, Van Der Woerd Jérôme (2021). The unexpected Mayotte 2018–2020 seismic sequence: a reappraisal of the regional seismicity of the Comoros. Comptes Rendus. Géoscience, 353(S1), 1-25. Publisher's official version : , Open Access version :