Sedimentary Records in the Lesser Antilles Fore‐Arc Basins Provide Evidence of Large Late Quaternary Megathrust Earthquakes

Type Article
Date 2024-02
Language English
Author(s) Seibert C.ORCID1, 2, Feuillet N.1, Ratzov Gueorgui3, Beck C.4, Morena PierreORCID3, 5, 6, Johannes L.7, Ducassou E.8, Cattaneo AntonioORCID5, Goldfinger C.9, Moreno E.ORCID10, Bieber A.ORCID1, 11, Bénâtre G.1, Caron B.ORCID12, Caron M.ORCID11, Casse M.11, Cavailhes T.8, Del Manzo G.ORCID1, Deschamps C. E.ORCID11, Desiage P. A.ORCID11, Duboc Q.11, Fauquembergue K.ORCID8, Ferrant Anthony13, Guyard H.1, Jacques E.1, Laurencin M.ORCID14, Leclerc F.ORCID3, Patton J.ORCID9, Saurel J. M.1, St‐onge G.11, Woerther Patrice13
Affiliation(s) 1 : Université de Paris Cité Institut de Physique du Globe de Paris CNRS Paris, France
2 : Lamont‐Doherty Earth Observatory of Columbia University Palisades NY ,USA
3 : Université Côte d'Azur CNRS, IRD Observatoire de la Côte d'Azur Géoazur Nice, France
4 : ISTerre, CNRS Université Savoie‐Mont‐Blanc Le Bourget du Lac ,France
5 : IFREMER, Geo‐Ocean UMR6538, Plouzané ,France
6 : Université de Brest LGO UMR 6538, Plouzané ,France
7 : Muséum National d'Histoire Naturelle, UMR 7207, Département Histoire de la Terre Paris ,France
8 : Université de Bordeaux, UMR CNRS 5805 EPOC Pessac,France
9 : College of Earth, Ocean, and Atmospheric Sciences Oregon State University Corvallis OR ,USA
10 : Laboratoire d’Océanographie et du Climat (LOCEAN) Sorbonne Université/CNRS/IRD/MNHN Paris ,France
11 : Institut des sciences de la mer de Rimouski (ISMER) Canada Research Chair in Marine Geology Université du Québec à Rimouski (UQAR) and GEOTOP Rimouski QC ,Canada
12 : Sorbonne Université CNRS‐INSU Institut des Sciences de la Terre de Paris ISTeP UMR 7193 Paris ,France
13 : Unité Recherche et Développements Technologiques Ifremer Plouzané ,France
14 : Laboratoire d’Océanologie et Géosciences Université de Lille Villeneuve d’Ascq, France
Source Geochemistry Geophysics Geosystems (1525-2027) (American Geophysical Union (AGU)), 2024-02 , Vol. 25 , N. 2 , P. e2023GC011152 (30p.)
DOI 10.1029/2023GC011152
Keyword(s) submarine paleoseismology, Lesser Antilles, turbidites, homogenites

The seismic potential of the Lesser Antilles subduction zone is poorly known and highly debated. Only two damaging earthquakes have been reported in the historical period, in 1839 and 1843, but their sources and magnitude are still uncertain. Global Navigation Satellite Systems and coral data contradict each other, and no conclusion has been reached on the coupling ratio of the plate interface. Given the threat posed by the possible occurrence of a large megathrust earthquake, it is crucial to gain information on prehistorical events. We present the results of a submarine paleoseismological study that covers an exceptional ∼120 Kyr‐long period. We studied the sediments sampled in six up to 26 m‐long piston cores collected in deep fore‐arc basins located over the epicentral region of the 1843 earthquake. Using a multiproxy approach combining geophysical, geochemical, and sedimentological analysis, biostratigraphy and radiocarbon dating, we identified, characterized, and dated numerous event deposits that we then correlated with the sampled basins over an up to 160 km‐long area. We show that at least 33 earthquakes likely triggered these sediment remobilizations in the last 120 Kyr. Four of these events promoted exceptional deposits of turbidites + homogenites. From peak ground acceleration calculated for potential earthquakes occurring on various faults, and the absence of deposits linked to the historical earthquakes, we propose that the sources are likely megathrust earthquakes. Over the last 60 Kyr, we inferred at least three 15–25 Kyr‐long seismic cycles in which the recurrence times of earthquakes shortens from ∼5 to ∼2 Kyr.

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Seibert C., Feuillet N., Ratzov Gueorgui, Beck C., Morena Pierre, Johannes L., Ducassou E., Cattaneo Antonio, Goldfinger C., Moreno E., Bieber A., Bénâtre G., Caron B., Caron M., Casse M., Cavailhes T., Del Manzo G., Deschamps C. E., Desiage P. A., Duboc Q., Fauquembergue K., Ferrant Anthony, Guyard H., Jacques E., Laurencin M., Leclerc F., Patton J., Saurel J. M., St‐onge G., Woerther Patrice (2024). Sedimentary Records in the Lesser Antilles Fore‐Arc Basins Provide Evidence of Large Late Quaternary Megathrust Earthquakes. Geochemistry Geophysics Geosystems, 25(2), e2023GC011152 (30p.). Publisher's official version : , Open Access version :