Abstract Wavefront systems may be divided into two broad classes, radiating (point source) and directed (line source). Radiating systems may be constructed for any point on the section when velocity distribution is known; directed wavefront systems are reconstructed from observed time-distance data and a knowledge of overburden velocities. The General Wavefront Method re-examines hitherto separately presented and time-tested classical techniques, together with certain novel and special applications, and shows that all are related by a single basic concept: an observed or deduced traveltime may be distributed between two appropriate wave-front systems, A and B , yielding a locus of general solutions and/or specific solutions. Depending on the particular problem various combinations of radiating and/or directed wavefronts are employed. The resulting easily constructed loci are related to curves of the simplest types; straight lines, circles, parabolas, hyperbolas, ellipses, and ovals, which in turn have a simple relationship to the desired interfaces (i.e., intersect on interface or are tangential to it). Complex problems of the kind encountered in the field are readily resolved by progressive reduction to simplest terms. Thus field cases, including multiple layers, high-relief structures involving penetration, faulting with attendant diffraction, and unusual travel paths, accelerating overburden velocities, etc., may all be handled on a routine basis. The usual sources of overburden velocity information are evaluated from the point of view of usefulness for the refraction method and particularly for wavefront interpretation. In addition, recording techniques incorporating existing wells into refraction surveys are presented as part of useful wavefront refraction lore.

Abstract Emergent wavefronts can be developed from traveltime data when the velocity is known by applying Huygens' principle in reverse. Targeting between complementary wavefronts provides a solution to a reversed profile that is independent of the refractor velocity. The agreement between two one-way solutions imposed thereon proves correctness. Reversed refraction profiling is the only geophysical method affording an interpretation which can be proved correct on the data alone. However, application of this fact is limited by recording conditions and velocity complexities.