The indirect boundary element method （IBME） is used to study three-dimensional scattering by an alluvial valley embedded in a layered half-space for obliquely incident plane SH waves; by using the direct stiffness method to calculate the free-field responses and dynamic Green＇s functions of moving distributed loads acting on inclined lines in a layered half-space to simulate the scatter wave filed responses. The presented, method yields very accurate results for the 3D dynamic stiffness matrixes and the fictitious uniform moving loads can be acted directly on the interface between the alluvial valley and the layered half-space without singularity. Numerical results and analyses are performed by taking the amplification of incident plane SH waves by an alluvial in a uniform half space and in one layer over half-space. The results show that the three-dimensional responses are distinctively different from the two-dimensional responses, and the displacement amplitudes around the valley in a uniform half-space are obviously different from those of in a layered half-space.[著者文摘]