The objective of this thesis is to improve the knowledge of tsunamis, hazard and coastal resonance in France. In the first part, we outlined the theory of free oscillations and tsunami modeling using long wave and Boussinesq approximations in a finite difference code. All these elements have been compared and validated during benchmarks. We developed a numerical code solving the hydrodynamic equations in the Boussinesq approximation. The second part is a set of applications in the Pacific Ocean and along the French coast. We studied different events produced in the Pacific Ocean. A detailed study of the tsunami generated by the Maule earthquake (Mw 8.8 February 28, 2010) is made in both in the near (at the Chilean coast) and far field (on DART and in French Polynesia). We compare the tsunami generated by different seismological sources of this event. We find that a simple source can reproduce the far-field observations. Along the Chilean coast, we study the large scale free oscillation generated by this event. Using data coming from different types of instrument (tide gauge, inclinometer), we demonstrate that these oscillations are generated by trapping waves between the trench and the coast. Because of various effects generated by tsunamis in the bays of French Polynesia depending on the earthquake location, a detailed study on resonance modes of the Marquesas was made containing a discussion of the dependence of the resonance on the azimuthal position of the source. Finally, a discussion of the tsunami hazard in metropolitan France was made. Due to a recent event (Boumerdes-Zemmouri, 2003), the tsunami risk on the Mediterranean coast is real. The study of additional events allows us to constrain better the risk. Less known, the tsunami risk on the French Atlantic coast was investigated by seeking past records of tsunamis. We validated the numerical simulations performed for the sources of the XX th century, leading to the first analysis of the impacts of tsunamis generated in the area Gibraltar--Azores on the French Atlantic coast.
