NUMERICAL SIMULATIONS OF SEVERAL SCENARIOS OF EARTHQUAKE-GENERATED TSUNAMI WAVE IN THE VICINITY OF GUADELOUPE ARCHIPELAGO: EFFECT OF THE MARIE-GALANTE GRABEN ON THE WAVE PROPAGATION
This study focuses on the propagation of tsunami waves within the Marie-Galante graben (MGB). MGB, located between 16°05N,61°55W & 15°40N,60°50W, is a deep structure (~ 2000 m deep) with an average slope of ~ 5°. Its highest flanks form shallow water environments which are areas prone to generate wave breaking and reflexion. We investigate these features using three tsunami sources: (i) two megathrust earthquake-generated sources considered as extreme cases to reproduce the two largest historical earthquakes known for this sector of the arc; (ii) one normal fault earthquake-generated source, a small source of ~ 15 km length located within the MGB structure on a major normal fault cutting through GA.
Two digital elevation models of 10 m and 100 m lateral resolution respectively and resulting from the compilation of several multibeam bathymetric data collected in the area for the past 10 years, are used. For each scenario the risk assessment on the nearest coasts from MGB is assessed by analyzing the wave time arrival and elevation but also the wave energy and frequency, the flooding area and the runoff. Lastly a parametric study of MGB's effect using the angle of incidence of the wave and the distance from the source is presented.
Numerical simulations of the tsunami sources are carried with TOPICS, a validated tsunami source modeling tool. Modeling of tsunami wave propagation is done with FUNWAVE TVD, a fully nonlinear and dispersive Boussinesq long wave model.