Numerical simulation of submarine landslides and generated tsunamis: application to the on-going Mayotte seismo-volcanic crisis

SinceMay 2018, Mayotte Island has been experiencing seismo-volcanic activities that could trigger submarine landslides and, in turn, tsunamis. To address these hazards, we use the HySEA numerical model to simulate granular flow dynamics and the Boussinesq FUNWAVE-TVD numerical model to simulate wave propagation and subsequent inundations. We investigate 8 landslide scenarios (volumes from 11.25x10(6) m(3) to 800x10(6) m(3)Mayotte, Seismo-volcanic crisis, Submarine landslide, Debris-avalanches, Tsunamis, Numerical modeling, Coastal flooding hazard). The scenario posing the greatest threat involves destabilization on the eastern side ofMayotte's lagoon at a shallowdepth and can generate sea-surface deformations of up to 2 m. We show that the barrier reef surroundingMayotte plays a prominent role in controlling water-wave propagation and in protecting the island. The tsunami travel time to the coast is very short (a few minutes) and the tsunami is not necessarily preceded by a sea withdrawal. Our simulation results provide a key to establishing hazard maps and evacuation plans and improving early-warning systems.