Induced water pressure profiles due to seismic motions

• Boundary element method applied to ocean problems.
• This leads to systems of integral equations.
• Pressures fields due to seismic motions are obtained.
• Results in frequency and time domain are presented.

About 90% of all natural earthquakes have epicenters in offshore areas and may cause damage to subsea and floating structures. These excitations can have effects on the performance of facilities installed on the seabed, like foundations, pipelines and subsea equipment for the oil industry. Several studies on this subject have been carried out to show the importance of seaquake analyses and their effects have been highlighted. In this paper the boundary element method is used to analyze the influence that some parameters, involved in this kind of problems, have on the dynamic response of marine waters under the incidence of theoretical seismic events. This method takes advantage of the elastodynamic Green's functions and, after the application of boundary conditions, a Fredholm system of integral equations is achieved and solved in frequency domain. Results in time domain are also obtained by applying a DFT algorithm. Flat and non-flat seabed configurations excited for normal and oblique incidence of P and S waves are considered. Pressure profiles through water depth are provided and synthetic seismograms of pressure are also shown. Amplifications of water pressures are emphasized.