Open AccessA one‐way wave equation for modelling seismic waveform variations due to elastic heterogeneity
Author(s) -
Angus D. A.
Publication year - 2005
Publication title -
geophysical journal international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0956-540X
DOI - 10.1111/j.1365-246x.2005.02695.x
Subject(s) - wavefront , diffraction , propagator , extrapolation , physics , wave propagation , seismic wave , scattering , isotropy , computational physics , optics , statistical physics , mathematical analysis , geophysics , mathematics , quantum mechanics
SUMMARY The application of a new one‐way narrow‐angle elastic wave equation to isotropic heterogeneous media is described. This narrow‐angle finite‐difference propagator should provide an efficient and accurate method of simulating primary body wave(s) passing through smoothly varying heterogeneous media. Although computationally slower than ray theory, the narrow‐angle propagator can model frequency‐dependent forward diffraction and scattering as well as the averaging effects due to smooth variations in medium parameters that vary on the sub‐Fresnel zone level. Example waveforms are presented for the propagation of body waves in deterministic as well as stochastic heterogeneous 3‐D Earth models. Extrapolation within deterministic media will highlight various familiar wave‐diffraction and pulse‐distortion effects associated with large‐scale inhomogeneities, such as geometrical spreading, wavefront folding and creeping‐wave diffraction by a compact object. Simulation within stochastic media will examine the effects of varying the correlation lengths of random heterogeneities on wave propagation. In particular, wave phenomena such as frequency‐dependent forward scattering, the appearance of random caustics and the generation of seismic coda will be shown.