Abstract: The scattering of P waves by a canyon of arbitrary shape in a fluid-saturated,poroelastic layered half-space was modeled using the indirect boundary element method in the frequency domain.The free-field responses were calculated to determine the displacements and stresses at the surface of the canyon,and fictitious distributed loads were then applied at the surface of the canyon in the free field to calculate the Green’s functions for displacements and stresses.The amplitudes of the fictitious distributed loads were determined from the boundary conditions,and the displacements arising from the waves in the free field and from the fictitious distributed loads were summed to obtain the solution.Numerical results for displacements of saturated layered systems were presented.The results were compared with those of the dry layered site.It was shown that the incident angle,the incident frequency and the parameters of b had great influence on displacements of saturated layered systems.The results of saturated sites were quite different from those of the dry layered site.The rationality and necessity of using the layered model were discussed.