DISPERSIVE BODY WAVES—AN EXPERIMENTAL STUDY

Abstract

Body‐wave dispersion is documented for a three‐dimensional case using the pulse propagation experiment in the Pierre Shale conducted by McDonal et al. (1958) and for a two‐dimensional case using ultrasonic pulse propagation in a Plexiglas plate. The magnitude of the dispersion for a five‐octave frequency band was only about two to three percent but easily observable by using Fourier‐analysis techniques. Body‐wave dispersion is shown to be predictable from the attenuation coefficient by following the causal transform technique of Futterman (1962). The principle of superposition is shown to be applicable for the prediction of the pulse anywhere in a medium if the complex propagation constant is known and if the pulse is known at one location. Pulse‐form prediction based on the attenuation coefficient alone is inadequate, while prediction based on attenuation and dispersion is in good agreement with observed results.