Guided waves as superposition of body waves

TL;DR

This paper explains guided waves, specifically Love and SH waves, as superpositions of body waves, revealing their propagation characteristics, mode structures, and speed relationships in layered media.

Contribution

It introduces a framework viewing guided waves as superpositions of body waves, clarifying mode formation and speed constraints in layered structures.

Findings

Love wave speed lies between SH wave speeds in layer and halfspace

Finite wavelength causes discrete modes with specific frequencies and speeds

Fundamental mode has lowest frequency and highest speed

Abstract

We illustrate properties of guided waves in terms of a superposition of body waves. In particular, we consider the Love and SH waves. Body-wave propagation at postcritical angles--required for a total reflection--results in the speed of the Love wave being between the speeds of the SH waves in the layer and in the halfspace. A finite wavelength of the SH waves--required for constructive interference--results in a limited number of modes of the Love wave. Each mode exhibits a discrete frequency and propagation speed; the fundamental mode has the lowest frequency and the highest speed.