Simulation of Tsunami Inundation for the Island of Martinique to Nearby Large Earthquakes

Abstract

ABSTRACT In this article, we estimate the tsunami hazard in Martinique due to tsunamis generated by earthquakes associated with the Lesser Antilles subduction zone. Using a deterministic approach based on reliable earthquake scenarios, we use high-resolution bathymetric and topographic data to model tsunami propagation and inundation with Cornell Multi-grid Coupled Tsunami model. An extreme earthquake subduction scenario of magnitude Mw 8.0 is tested, and a further realistic scenario of lower magnitude Mw 7.5, thus of different tsunami frequency content, is also processed to test the possible appearance of bay resonances. We find that the western coast of the island is relatively sheltered, because it represents a shadow area to diffraction, in particular, for the major city of Fort de France. Because of its very gentle slope, the eastern coast is prone to numerous floodings with meter scale wave amplitudes; most of the inundated zones consist of mangroves and geological depressions t are naturally regularly flooded by tides or storm surges. Hence such areas are often not exploited, the mangroves being let in their natural state, enhancing the protection of the surrounding communities. However, some strategic inhabited areas are subject to severe inundation. Finally, comparing our results with studies of the 1755 Lisbon transoceanic tsunami reveals a tsunami hazard close to our local Mw 7.5 scenario. It suggests the possibility to generalize our local tsunami hazard assessment in Martinique to other tsunami contexts and enlarge its validity. This issue is crucial for minimizing the efforts and increasing the efficiency of tsunami preparedness.