Tsunami warning in French Polynesia: new tools applied to historical events.

Abstract:

The tsunami warning process classically involves a two stages procedures: the first one concerns the estimation of the source parameters (i.e. location of the centroïd, seismic moment, focal geometry, faults dimensions); the second one is the tsunami height estimation that is achieved through numerical modeling of the tsunami propagation in deep ocean and along the shores, for a given limited number of sites in French Polynesia.

We present a study applied to about twenty tsunamigenic earthquakes that occurred around the Pacific rim between 1960 to 2012. For recent events (younger than 1990's) the seismic sources parameters has been reevaluated with 2 methods: one involving an inversion of the surface waves in the long period domain, and the second one involving an inversion of the W-PHASE in the ultra long period domain. For older ones, the published sources parameters were used for the tsunami simulations.

The tsunami modeling is performed via parallel computing on nested grids for some selected sites of French Polynesia, and the results will be compared to the observations and/or measurements given by sea-level instruments. The case of some problematic (complex, slow) events will be then detailed.