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Morphotectonic characteristics of the Lesser Antilles fore-arc region, preliminary results of ANTITHESIS cruise


IPGP - Îlot Cuvier


Séminaires Tectonique et Mécanique de la Lithosphère

Salle 310

Thibaud Pichot


Advance in geodetic data and marine geophysical techniques revealed that fore-arc region are composed of distinct morphological elements of along-dip segmentations related to the accommodation of convergent motions acting at subduction zone. Moreover, variations through time of sediment supply and lower plate structure lead to along-strike segmentation. Fore-arc region hosts nucleation and/or propagation of great interplate earthquakes. Recent works have shown that frictional properties on the plate interface control trench-parallel variations in the fore-arc topography, gravity and seismogenic behavior. Seismic hazards in the Lesser Antilles subduction zone remains poorly understood and up to now we have few information on magnitude, and recurrence time of mega-thrust in this area. In the past decade, several marine geophysical cruises have greatly improved our understanding of the structure of the central segment of the fore-arc Lesser Antilles. However, the northern segment from Guadeloupe to Virgin Islands remains less investigated. To overcome this, the ANTITHESIS cruise was conducted from November 24th 2013 to January 7th 2014 to investigate the crustal structure of the fore-arc between Virgin Islands and Anguilla. Here, I will present an overview of the Lesser Antilles fore-arc region in the light of recent marine geophysical cruises and more specially the ANTITHESIS cruise. I will discuss the along-strike morphotectonic variations from frontal to oblique convergence margins acting at the Lesser Antilles subduction zone and possible implications of the frictional properties on the plate interface.