{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,3]],"date-time":"2026-09-03T07:48:49Z","timestamp":1788421729779,"version":"build-2803163510"},"reference-count":37,"publisher":"Society of Exploration Geophysicists","issue":"3","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[1998,6,1]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>P-wave amplitudes may be sensitive even to relatively weak anisotropy of rock mass. Recent results on symmetry-plane P-wave reflection coefficients in azimuthally anisotropic media are extended to observations at arbitrary azimuth, large incidence angles, and lower symmetry systems. The approximate P-wave reflection coefficient in transversely isotropic media with a horizontal axis of symmetry (HTI) (typical for a system of parallel vertical cracks embedded in an isotropic matrix) shows that the amplitude versus offset (AVO) gradient varies as a function of the squared cosine of the azimuthal angle. This change can be inverted for the symmetry-plane directions and a combination of the shear-wave splitting parameter \u03b3 and the anisotropy coefficient \u03b4(V).<\/jats:p>\n                  <jats:p>The reflection coefficient study is also extended to media of orthorhombic symmetry that are believed to be more realistic models of fractured reservoirs. The study shows the orthorhombic and HTI reflection coefficients are very similar and the azimuthal variation in the orthorhombic P-wave reflection response is a function of the shear-wave splitting parameter \u03b3 and two anisotropy parameters describing P-wave anisotropy for near-vertical propagation in the symmetry planes.<\/jats:p>\n                  <jats:p>The simple relationships between the reflection amplitudes and anisotropic coefficients given here can be regarded as helpful rules of thumb in quickly evaluating the importance of anisotropy in a particular play, integrating results of NMO and shear-wave-splitting analyses, planning data acquisition, and guiding more advanced numerical amplitude-inversion procedures.<\/jats:p>","DOI":"10.1190\/1.1444405","type":"journal-article","created":{"date-parts":[[2002,10,11]],"date-time":"2002-10-11T15:52:42Z","timestamp":1034351562000},"page":"935-947","source":"Crossref","is-referenced-by-count":454,"title":["Variation of\n                    <i>P<\/i>\n                    -wave reflectivity with offset and azimuth in anisotropic media"],"prefix":"10.1190","volume":"63","author":[{"given":"Andreas","family":"R\u00fcger","sequence":"first","affiliation":[{"name":"*Formerly Department of Geophysics, Center for Wave Phenomena, Colorado School of Mines, Golden, CO; presently Landmark Graphics, 7409 S. Alton Court, Englewood, CO 80112. E-mail: andreas@advance.com."}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"186","published-online":{"date-parts":[[1998,6,1]]},"reference":[{"key":"R1","unstructured":"Aki, K., and Richards, P. G., 1980, Quantitative seismology: Theory and methods,\n                      1\n                      : W. H. Freeman & Co."},{"key":"R2","doi-asserted-by":"crossref","unstructured":"Alford, R. M., 1986, Shear data in the presence of azimuthal anisotropy: 56th Ann. Internat. Mtg., Soc. Expl. Geophys., Expanded Abstracts, 476\u2013479.","DOI":"10.1190\/1.1893036"},{"key":"R3","doi-asserted-by":"publisher","DOI":"10.1190\/1.1442282"},{"key":"R4","doi-asserted-by":"publisher","DOI":"10.1111\/j.1365-2478.1961.tb01670.x"},{"key":"R5","unstructured":"Corrigan, D., 1990. The effect of azimuthal anisotropy on the variation of reflectivity with offset: Workshop on Seismic Anisotropy: Soc. Expl. 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