Reflection Seismology in Azimuthally Anisotropic Media

Leon Thomsen

Many recent papers have suggested that crustal rocks may be azimuthally anisotropic to some degree. Such anisotropy is usually attributed to joints, fractures, or microcracks aligned by a horizontal minimum stress to lie vertically and with a preferred azimuth. In this talk, I present a heuristic discussion of the effects of such anisotropy on seismic reflection data (both in traveltime anomalies and in reflection amplitude anomalies). New mathematical results, based on a model of transverse isotropy with symmetry axis horizontal, verify the heuristic discussion. In addition, mathematical results for moveout velocity, as compared with vertical velocity, show the moveout to be abnormal and, in part, counterintuitive.

AAPG Search and Discovery Article #91038©1987 AAPG Annual Convention, Los Angeles, California, June 7-10, 1987.