Numerical simulation of seismic wave triggered by low-frequency sound source with 3D staggered-grid difference method in shallow water

Ship seismic wave is often used for targeting ship location. This elastic wave that traveled in the seabed layer is triggered by low-frequency ship noise. At present, most of the theoretical studies of ship seismic wave were conducted in the frequency domain and the wave components such as P-wave, S-wave, and normal mode wave cannot be distinguished. In this study, the propagation characteristics were studied by numerical simulation in the time domain based on 3D staggered-grid finite difference method whose availability was firstly verified through a theoretical solution. The numerical simulation results show that seismic waves in the seabed layer were dominated by transmitted S-wave and interface wave in the near-field area, and transmitted P-wave is not obvious here, while seismic waves were dominated by normal mode and interface wave in the far-field area, and when the sound source is moved away from the seafloor, the amplitude of normal mode wave becomes larger, but the amplitude of interface wave becomes smaller.