If a sharp edge occurs in a reflector, the wavefield predicted by geometric ray theory shows shadow boundaries between illuminated zones and shadow zones. One may correct for these discontinuities in the wavefield by adding edge waves as introduced by Klem-Musatov. In this paper the edge wave is analysed as a solution of a parabolic differential equation that describes transverse diffusion between the illuminated zone and the shadow zone across the shadow boundary. Here, the edge wave is described constructively in terms of dynamic ray tracing, thereby indicating how it can be implemented in a ray tracing program when the latter is equipped with the facility of dynamic ray tracing.
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The use of diffraction imaging to complement the seismic reflection method is rapidly gaining momentum in the oil and gas industry. As the industry moves toward exploiting smaller and more complex conventional reservoirs and extensive new unconventional resource plays, the application of the seismic diffraction method to image sub-wavelength features such as small-scale faults, fractures and stratigraphic pinchouts is expected to increase dramatically over the next few years. “Seismic Diffraction” covers seismic diffraction theory, modeling, observation, and imaging. Papers and discussion include an overview of seismic diffractions, including classic papers which introduced the potential of diffraction phenomena in seismic processing; papers on the forward modeling of seismic diffractions, with an emphasis on the theoretical principles; papers which describe techniques for diffraction mathematical modeling as well as laboratory experiments for the physical modeling of diffractions; key papers dealing with the observation of seismic diffractions, in near-surface-, reservoir-, as well as crustal studies; and key papers on diffraction imaging.