Transient Response of an Ice-Water-Covered Transversely Isotropic Poroelastic and Multilayered Medium Under Vertical P-Wave Incidence

Formation of ice layers during winter is a common natural phenomenon in high-latitude regions. To evaluate the impact of the ice layer on the seismic response of a poroelastic medium, we develop a novel model to describe the dynamic interaction among the ice layer, water layer, and transversely isotropic poroelastic rock under vertical P-wave excitation. First, the general solutions for the poroelastic rock and overlying water and ice layers are derived by applying the Laplace transform. Then the dual-variable and position (DVP) method is employed to obtain a semi-analytical solution of the layered media in the transform domain. By applying a numerical inverse Laplace transform scheme, the time response of free-field motion in the layered rock under P-wave excitation is obtained. Numerical results show that the ice layer causes more complex waveforms and amplifies the vertical displacement in deeper locations in the poroelastic medium with low permeability. A higher anisotropic modulus ratio leads to an earlier arrival of displacement peaks and troughs, with this effect strengthening over time. Stiff interlayers amplify the displacement and advance the waveform, while soft interlayers have the opposite effect.