Wave propagation in multilayered media: the effect of waveguides in oceanic and continental Earth models

We investigate the effect of low-velocity waveguides on ground motion. The computation of eigenvalues and eigenfunctions of Rayleigh waves up to the frequency 10.0 Hz allows an analysis of the seismic response which is source independent. The main conclusions of this study are: (1) Extending the model to depths greater than that of the waveguides allows the exact computation of leaking modes. (2) A source in a layered structure generates P waves of higher frequency than S waves even if the structure is purely elastic. (3) At high frequencies (10.0 Hz) the modal components of P waves separate from those of SV waves. (4) Strong surface waves are generated by shallow sources in sedimentary basins, also at a source distance of a few tens of kilometres. These waves do not appear in structures without sediments. (5) The polarization of strong ground motion at the surface of low-velocity layers is mainly horizontal. (6) For oceanic models, the contribution of the sedimentary layers is separable from that of the water layer only at high frequencies.           ARK: https://n2t.net/ark:/88439/y014925 Permalink: https://geophysicsjournal.com/article/294 &nbsp