A 2.5D generalized first-order wave equation to accommodate various elastic media and different boundary conditions

We present a 2.5D generalized first-order time-domain governing equation to model seismic waves propagation in acoustic, elastic isotropic and anisotropic media, as well as at the air-water, air-solid and water-solid interfaces with a single computer program. In order to verify the proposed wave equation, we numerically solve it by a curvilinear finite-difference method, which exactly matches free-surface topography and undulating subsurface interfaces. The comparison between the numerical wave solutions and the theoretical wave-fronts in various media (acoustic, isotropic and anisotropic media) shows good agreements, and the results of seismic wave propagation at different boundaries (air-water, air-solid and undulating water-solid interfaces) demonstrate clear reflection, conversion and transmission waveforms, which confirm the correctness of the proposed wave equation.