Near-field of a seismic source in a layered medium with irregular interfaces

Abstract

Summary A method based on a discrete wavenumber representation of elastic wave fields is developed and applied to the study of the radiation and scattering in the vicinity of a seismic source located in an irregularly layered medium. The discretization results from a periodicity assumption in the description of the source and of the medium. The problem is two-dimensional but the source can be quite general and is represented by its body force equivalents. The method is an extension of the Aki-Larner technique originally developed to study the scattering of plane waves at irregular boundaries. It is applicable to wavelengths which are either longer than, or of the order of, the dimensions of the irregularities. A study of the strong motion response of a sedimentary basin to a nearby earthquake is presented, for which the main result is a large amplification of horizontal motions.