This presentation is a survey of selected frequency-dependent phenomena routinely encountered in reflection seismic data. At first impression the topic seems self-evident; everything is frequency dependent. However, much of classical seismology and wave theory is non-dispersive — the theory of P and S waves, Rayleigh waves in a half-space, geometric spreading, reflection and transmission coefficients, head waves, etc. The convolutional reflection models we use to model thick and thin bed thin response, as well as most inversion techniques, do not include dispersion phenomena. And yet when we look at real data, strong dispersion abounds.

The classical meaning of the word dispersion is frequency-dependent velocity. We take a more general definition that includes not just wave speed, but also interference, attenuation, anisotropy, reflection characteristics and other aspects of seismic waves that show frequency-dependence. We will examine the interpretive challenges presented by the reality of dispersion using modern, real data examples.

This presentation is a summary of Dr. Liner’s 2012 SEG Distinguished Instructor Short Course, scheduled in Houston on April 20, 2012.

Figure 1. Interference beyond the thin bed.

Figure 2. 6 Hz timeslice