EGU21-934, updated on 03 Mar 2021
https://doi.org/10.5194/egusphere-egu21-934
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Vertical tectonic motions in the Lesser Antilles: linking short- and long-term observations

Elenora van Rijsingen1, Eric Calais1,2, Romain Jolivet1,2, Jean-Bernard de Chabalier3, Richard Robertson4, Graham Ryan4, and Steeve Symithe5
Elenora van Rijsingen et al.
  • 1Ecole Normale Supérieure, PSL Research University, CNRS UMR 8538
  • 2Institut Universitaire de France
  • 3Institut de Physique du Globe de Paris, Sorbonne Paris Cité, CNRS UMR 7154
  • 4University of the West Indies
  • 5Université d'Etat d'Haiti

Horizontal GPS velocities show that the Lesser Antilles subduction zone is currently experiencing low interseismic coupling, meaning that little to no elastic strain is building up as the North- and South American plates subduct beneath the Caribbean plate. However, geological data on Quaternary coral terraces and active micro-atolls in the central part of the arc reveal slow subsidence over the past 125,000 to 100 years, likely tectonic in origin. It has been proposed that coupling along the subduction interface could be responsible for this geological subsidence. We use forward elastic models with a realistic slab geometry to show that a locked subduction interface would actually produce uplift of the island arc, which contradicts these geological observations. We also show that vertical GPS data in the Lesser Antilles indicates a subsidence of 1-2 mm/yr of the entire arc. This short-term subsidence is in agreement with the ~100-year trend of 1.1 mm/yr subsidence derived from coral micro-atolls in eastern Martinique. Since locking of the subduction interface is inconsistent with this observed subsidence of the arc, we explore other mechanisms that could this observation, such as postseismic effects of historical earthquakes, slab retreat, tectonic erosion, accretionary wedge collapse or extension in the overriding plate. 

How to cite: van Rijsingen, E., Calais, E., Jolivet, R., de Chabalier, J.-B., Robertson, R., Ryan, G., and Symithe, S.: Vertical tectonic motions in the Lesser Antilles: linking short- and long-term observations, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-934, https://doi.org/10.5194/egusphere-egu21-934, 2021.

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