Lesser Antilles Seismotectonic Zoning Model for Seismic Hazard Assessment

Abstract. Subduction zones pose a considerable challenge within the realm of seismotectonics, owing to their faults and structures interactions. The Lesser Antilles arc is a good example of how these complexities impact seismic hazard studies with a strong along-strike variations in tectonic, seismic, and volcanic activities. While they have generated significant damages, the 1839 and 1843 event characteristics (locations, depths, mechanisms, magnitudes) remain a subject of debate along with their potential implications in the megathrust seismicity, in particular in the frame of low interseismic coupling. This study is grounded in the compilation of instrumental and historical seismicity, and fault catalogs, completed by analyses of focal mechanisms and rupture types as well as geodetic velocities and strain rates. The seismotectonic model and zoning of the Lesser Antilles encompass the upper plate, subducting oceanic plate, subduction interface, mantle wedge, and volcanoes. We propose a better depth resolution, resulting from recent studies on slab top and upper plate bottom geometries, a specific area source for the Marie-Galante graben, new propositions for mantle wedge and volcanic zoning, and fully revised area sources for the subduction interface. Our study highlights specific needs for a better seismic hazard assessment in this region.