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Two hundred thirty years of relative sea level changes due to climate and megathrust tectonics recorded in coral microatolls of Martinique (French West Indies)

Weil-Accardo, Jennifer and Feuillet, Nathalie and Jacques, Eric and Deschamps, Pierre and Beauducel, François and Cabioch, Guy and Tapponnier, Paul and Saurel, Jean-Marie and Galetzka, John (2016) Two hundred thirty years of relative sea level changes due to climate and megathrust tectonics recorded in coral microatolls of Martinique (French West Indies). Journal of Geophysical Research. Solid Earth, 121 (4). pp. 2873-2903. ISSN 2169-9313. http://resolver.caltech.edu/CaltechAUTHORS:20160909-095857547

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Abstract

We sampled six coral microatolls that recorded the relative sea level changes over the last 230 years east of Martinique, on fringing reefs in protected bays. The microatolls are cup-shaped, which is characteristic of corals that have been experiencing submergence. X-ray analysis of coral slices and reconstructions of the highest level of survival (HLS) curves show that they have submerged at rates of a few millimeters per year. Their morphology reveals changes in submergence rate around 1829 ± 11, 1895, and 1950. Tide gauges available in the region indicate a regional sea level rise at a constant mean rate of 1.1 ± 0.8 mm/yr, which contrasts with our coral record, implying additional tectonic subsidence. Comparing our coral morphology with that of synthetic corals generated with Matlab by using the Key West tide gauge record (Florida), we show that their growth was controlled by tectonics and that a sudden relative sea level increase drowned them around 1950. Simple elastic models show that this sudden submergence probably occurred during the 21 May 1946 earthquake, which ruptured the plate interface in front of Martinique, in the mantle wedge, in an area of sustained seismic activity. The 1839 M8+ earthquake probably occurred in the same area. Long-term subsidence of microatolls indicates that this deep portion of the megathrust is probably locked down to 60 km depth during the interseismic period. Our oldest coral recorded a long-lasting period (50 years) of stable relative sea level after the 1839 earthquake, indicating that transient interseismic strain rate variations may occur in the Lesser Antilles.


Item Type:Article
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http://dx.doi.org/10.1002/2015JB012406DOIArticle
http://onlinelibrary.wiley.com/doi/10.1002/2015JB012406/abstractPublisherArticle
Additional Information:© 2016 American Geophysical Union. Received 3 AUG 2015; Accepted 24 FEB 2016; Accepted article online 27 FEB 2016; Published online 8 APR 2016. We thank Frédérique Leclerc, Yann Klinger, and Bruno Hamelin for helpful discussions. A special thanks to Belle Philibosian for the fruitful proofreadings and very helpful discussions. We sincerely thank Benoît Taisne of the Earth Observatory of Singapore, who helped us to model the volcanoes' impact on the relative sea level changes. Thanks to Guy Wöppelmann of the LIttoral ENvironnement et Sociétés (LIENSs) for his help in improving our discussion of the regional sea level rise with the use of GPS records. The fieldwork required help from the Volcanologic and Seismologic Observatory of Martinique, and we sincerely thank the whole observatory team for their logistic help and their participation in the field. We thank Christophe Yvon for underwater photography. Thanks to the Saint-Paul clinic of Fort-de-France for the free X-rays of coral slices and for their interest in the research project. Thanks to Cyril Giry for help in estimating counting uncertainties. Pierre Deschamps is supported by the Agence Nationale de la Recherche (Project EQUIPEX ASTER-CEREGE). The project was funded by the ANR CATTELL SUBSISMANTI and the INSU (CT3 ALEAS). Data are included in the main text and supporting information files as figures; any additional information may be obtained on request at IPGP email: weilaccardo@ipgp.fr. This is IPGP contribution 3727.
Group:Seismological Laboratory
Funders:
Funding AgencyGrant Number
Agence Nationale de la Recherche (ANR)EQUIPEX ASTER-CEREGE
Agence Nationale de la Recherche (ANR)CATTELL SUBSISMANTI
Institut National des Sciences de l'Univers (INSU)CT3 ALEAS
Subject Keywords:coral microatoll; Lesser Antilles megathrust; relative sea level change; seismic cycle; paleoseismology; paleogeodesy
Record Number:CaltechAUTHORS:20160909-095857547
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20160909-095857547
Official Citation:Weil-Accardo, J., N. Feuillet, E. Jacques, P. Deschamps, F. Beauducel, G. Cabioch, P. Tapponnier, J.-M. Saurel, and J. Galetzka (2016), Two hundred thirty years of relative sea level changes due to climate and megathrust tectonics recorded in coral microatolls of Martinique (French West Indies), J. Geophys. Res. Solid Earth, 121, 2873–2903, doi:10.1002/2015JB012406
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:70232
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:09 Sep 2016 17:55
Last Modified:03 Oct 2016 17:24

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