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Lookup NU author(s): Dr Anne-Sophie Meriaux
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
© 2021The seismic potential of the Lesser Antilles megathrust remains poorly known, despite the potential hazard it poses to numerous island populations and its proximity to the Americas. As it has not produced any large earthquakes in the instrumental era, the megathrust is often assumed to be aseismic. However, historical records of great earthquakes in the 19th century and earlier, which were most likely megathrust ruptures, demonstrate that the subduction is not entirely aseismic. Recent occurrences of giant earthquakes in areas where such events were previously thought to be improbable have illustrated the importance of critically evaluating the seismic potential of other “low-hazard” subduction zones, such as the Lesser Antilles. Using the method of coral microatoll paleogeodesy developed in Sumatra, we examine 20th-century vertical deformation on the forearc islands of the Lesser Antilles and model the underlying strain accumulation on the megathrust. Our data indicate that the eastern coasts of the forearc islands have been subsiding by up to ∼8 mm/yr relative to sites closer to the arc, suggesting that on the time scale of the 20th century, a portion of the megathrust just east of the forearc islands has been locked. Our findings are in contrast to recent models based on satellite geodesy that suggest little or no strain accumulation anywhere along the Lesser Antilles megathrust. This discrepancy is potentially explained by the different time scales of measurement, as recent studies elsewhere have indicated that interseismic coupling patterns may vary on decadal time scales and that century-scale or longer records are required to fully assess seismic potential. The accumulated strain we have detected will likely be released in future megathrust earthquakes, uplifting previously subsiding areas and potentially causing widespread damage from strong ground motion and tsunami waves.
Author(s): Philibosian B, Feuillet N, Weil-Accardo J, Jacques E, Guihou A, Meriaux A-S, Anglade A, Saurel J-M, Deroussi S
Publication type: Article
Publication status: Published
Journal: Earth and Planetary Science Letters
Year: 2022
Volume: 579
Print publication date: 01/02/2022
Online publication date: 03/01/2022
Acceptance date: 10/12/2021
Date deposited: 08/06/2023
ISSN (print): 0012-821X
Publisher: Elsevier B.V.
URL: https://doi.org/10.1016/j.epsl.2021.117343
DOI: 10.1016/j.epsl.2021.117343
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