SH-type wave motion in a geophysical model with monoclinic and heterogeneous media due to a point source at the interface

摘要

Abstract The paper examines SH-type surface waves in a locally elastic heterogeneous half-space that is governed by a point source in a finite-thickness heterogeneous monoclinic layer. The heterogeneity parameter in the top monoclinic layer is expected to vary logarithmically, whereas the heterogeneity parameter in the bottom elastic half-space is expected to vary quadratically. A point source of disturbance, situated at the common interface of the layer and the semi-infinite medium, generates the SH-type surface waves in the layered structure. Green’s function approach and the Fourier transformation are used to obtain dispersion equations from governing equations with proper boundary equations. By using unique numerical values of stiffness and density associated with heterogeneous characteristics, MATLAB software has been used to represent phase velocity associated with SH-type surface wave propagation. This is to reflect the phase velocity’s nature. It has been observed that as the heterogeneity parameter corresponding to both the top monoclinic layer and the bottom elastic half-space increases, the phase velocity of SH-type surface waves decreases. This is consistent with the classical nature of SH-type surface waves propagating in heterogeneous media. The novelty of this paper is that the dispersion in heterogeneous media with high phase velocity is smaller than the dispersion in homogeneous media with low phase velocity.