ISOCHRONS FOR A THREE‐DIMENSIONAL SEISMIC SYSTEM

Abstract

The three‐dimensional seismic system discussed by Walton (1970–1971) explores seismically a column of earth extending from the surface to deep reflectors. Interpretation of data from the system is done directly from displays on a grid of the detected signals. In this paper we derive expressions for the patterns expected on three‐dimensional system displays when energy returning to the detectors consists of reflections from planes, diffractions from faults or point scatterers, reflections from reflectors of arbitrary shape, refractions and reflected‐refractions from planes, or direct or surface waves. Examples of typical patterns are shown. Our derivations are limited to ray geometry and shed no light on amplitude variations. Also, an average velocity from the surface to a reflector, refractor, or diffractor is assumed.