Based on a two-layered viscous fluid theory, a numerical model to capture the progressive nature of wave-induced liquefaction has been developed. Unlike the existing models, this model can consider the cyclic shear stress associated with vibrating liquefied soil layers and its effect on sub-liquefied soils during the wave-induced liquefaction. The reliability of this model is validated by simulating wave flume tests, which show a promising prediction when compared to analytical solutions, particularly after the onset of liquefaction where an increased amplitude in the oscillatory pore water pr...