Diffraction of plane harmonic P, SV, and Rayleigh waves by dipping layers of arbitrary shape is investigated by using an indirect boundary integral equation approach. The layers are of finite length perfectly bonded together. The material of the layers is assumed to be homogeneous, weakly anelastic, and isotropic. The displacement field is evaluated throughout the elastic medium so that the continuity of the displacement and the traction fields along the interfaces between the layers is satisfied in a least-squares sense.
Presented numerical results show that the surface strong ground motion amplification effects depend upon a number of parameters present in the problem, such as, type, frequency, and angle of the incident wave, the impedance contrast between the layers, the component of the displacement field being observed, and the location of the observation point at the surface of the half-space.
The results demonstrate that the presence of soft alluvial deposits in form of dipping layers may cause locally very large amplification or reduction of the surface ground motion when compared with corresponding free-field motion.