Seismo-acoustic wave propagation in the Rade of Hyères (France) generated by counter-mining of explosive devices: comparison between numerical simulations and real experiments

In order to study the impact of the potential explosion of WWII unexploded ordnances which are commonly found along the French Mediterranean coast, a series of underwater explosions were conducted in December 2018 in the Rade of Hyeres in France. These explosions were realized within the framework of the POSA project, led by SHOM, and which includes LMA, Geoazur and LPG Nantes which addresses the upstream hazard management issue of such counter-mining operations in the marine field. From topographical and sedimentary measurements performed in this area, physical and geometrical characteristics of the marine seabed have been carefully selected to serve as input data for numerical simulations of seismo-acoustic wave propagation from the source to several seismometers deployed on the coast of Hyeres and surrounding islands. Numerical simulations were conducted using a spectral-element method in the time domain. The impact of the explosive device (source) charge and its location (on the seabed or in the water column), together with the impact of the marine environment properties, on the simulated signals have been studied. The source time function is estimated from in situ acoustic signals recorded by hydrophones located around the detonation location. The seismic data recorded on the coast are used to calibrate the numerical simulation and to evaluate the impact of different marine environments with special attention to the influence of the characteristics of the sediment layer.In order to study the impact of the potential explosion of WWII unexploded ordnances which are commonly found along the French Mediterranean coast, a series of underwater explosions were conducted in December 2018 in the Rade of Hyeres in France. These explosions were realized within the framework of the POSA project, led by SHOM, and which includes LMA, Geoazur and LPG Nantes which addresses the upstream hazard management issue of such counter-mining operations in the marine field. From topographical and sedimentary measurements performed in this area, physical and geometrical characteristics of the marine seabed have been carefully selected to serve as input data for numerical simulations of seismo-acoustic wave propagation from the source to several seismometers deployed on the coast of Hyeres and surrounding islands. Numerical simulations were conducted using a spectral-element method in the time domain. The impact of the explosive device (source) charge and its location (on the seabed or in the water...