MAPPING OF THE TSUNAMI INUNDATION AND INTENSITY ALONG THE COAST OF LA MARTINIQUE ISLAND DUE TO THE SEISMICITY

We estimate the tsunami hazard in Martinique due to tsunamis generated by earthquakes associated with local, regional and distant earthquakes. Using a deterministic approach based on reliable earthquake scenarios, we use high resolution bathymetric and topographic data to model tsunami propagation and inundation with COMCOT. An extreme earthquake subduction local (Mw 8.0) a further realistic scenario of lower magnitude Mw 7.5, Virgin Island – regional (Mw 8.0) scenario and Lisbon 1755 - distant scenario (Mw 8.0), are tested, thus of different tsunami frequency content, is also processed in order to test the possible appearance of bay resonances. On land, 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. Due to its very gentle slope, the eastern coast is prone to numerous floodings, with meter-scale wave amplitudes: most of the inundated zones consist in mangroves and geological depressions which 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. Four occupied locations are however exposed to severe inundation (hundreds of horizontal meters): Pointe Marin, Le Vauclin, Le Robert and, for the largest, Baie de la Trinité. Finally, comparing our results of the 1755 Lisbon transoceanic tsunami reveals a tsunami hazard close to our local Mw 7.5 scenario. It suggests the possibility to generalize tsunami hazard assessment in Martinique from local sources to other tsunami contexts and enlarge its validity. This issue is crucial for minimizing the efforts and increasing the efficiency of tsunami preparedness.