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Seismic focusing by a single planar fracture
Author(s) -
Oliger A.,
Nolte D. D.,
PyrakNolte Laura J.
Publication year - 2003
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2002gl016264
Subject(s) - geology , seismology , fracture (geology) , anelastic attenuation factor , refraction , seismic wave , amplitude , reflection (computer programming) , seismic anisotropy , seismic refraction , dispersive body waves , geophysics , optics , geotechnical engineering , physics , mantle (geology) , computer science , programming language
A single plane fracture with an axially symmetric stress distribution behaves as a seismic lens that focuses seismic energy to a beam “waist” at a focal plane. Both phase and amplitude effects on a seismic wave propagating across the fracture contribute to the lensing behavior. Radial gradients in the fracture specific stiffness cause wave refraction through a radially varying group time delay, while the fracture transmission amplitude approximates a Fresnel zone plate. This work demonstrates that a two‐dimensional planar fracture, contrasted with three‐dimensional geologic structures such as basins and domes, can focus seismic waves. Focusing of seismic waves by fractures should be considered in the interpretation of seismic data from fractured strata with heterogeneous stress distributions.