Provides an overview of the source signal components, and examines the source signatures and amplitude spectra of several different seismic sources. Reviews properties of the seismic pulse, explores measurement of source array responses, compares wavefront and ray properties, and discusses how acoustic impedance and particle velocity can be used to infer subsurface rock types. Discusses the processes of seismic decay, specifically geometrical spreading, attenuation, absorption and scattering, and their effect on the source signature. Examines small source and near field effects, and how to compensate for signal loss. Provides an overview of ray tracing laws and principles, specifically Snell's Law, Fermat's Principle, Huygens' Principle, Huygens' – Fermat's Principle, and the Principle of Reciprocity. Supplies ray theory formulas, and explains how to construct wavefront counterparts from rays.