Forearc crustal faults as tsunami sources in the upper plate of the Lesser Antilles subduction zone: the case study of the Morne Piton fault system

A recent study identifies trench-perpendicular upper plate normal faults, such as the Morne Piton Fault system off northern Martinique, as potential tsunami sources along the Lesser Antilles subduction zone. Using seismic reflection, high-resolution bathymetry, Remotely Operated Vehicle (ROV) imagery, and dating techniques, researchers reassessed the fault's slip rate at 0.2 mm/year since its inception 7 million years ago—significantly lower than previous estimates. This finding suggests a longer earthquake recurrence interval and reduced seismic hazard. The study also reveals evidence of recent fault rupture, with a modeled magnitude range of Mw 6.5 ± 0.5 for potential seismic events. A multi-segment tsunami model demonstrates the worst-case scenario impacts on coastal areas, highlighting how shallow water plateaus, canyons, and resonance within Les Saintes archipelago could amplify and prolong tsunami effects, posing risks to populated and touristic regions.

Philippon, M., Roger, J., Lebrun, J.-F., Thinon, I., Foix, O., Mazzotti, S., Gutscher, M.-A., Montheil, L., & Cornée, J.-J. (2024). Forearc crustal faults as tsunami sources in the upper plate of the Lesser Antilles subduction zone: the case study of the Morne Piton fault system. Natural Hazards and Earth System Sciences, 24(9), 3129–3154. https://doi.org/10.5194/nhess-24-3129-2024