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SEISMIC MODEL STUDIES ON DIFFRACTION OF WAVES BY EDGES OF VARYING RADIUS OF CURVATURE AND DEPTH *
Author(s) -
DATTA S.,
BHOWMICK A. N.
Publication year - 1974
Publication title -
geophysical prospecting
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.735
H-Index - 79
eISSN - 1365-2478
pISSN - 0016-8025
DOI - 10.1111/j.1365-2478.1974.tb00104.x
Subject(s) - diffraction , amplitude , radius , curvature , radius of curvature , enhanced data rates for gsm evolution , physics , geometry , surface (topology) , surface wave , optics , mathematics , mean curvature , telecommunications , computer security , mean curvature flow , computer science
A bstract Results of studies carried out with the help of a three‐dimensional seismic model on waves diffracted from edges of varying radius of curvature R and depth h with respect to wave length λ are described. The amplitude decay, travel time, and apparent velocity of the wave diffracted from a sub‐surface edge of semi‐infinite length are found to depend on the parameters R, h , and distance from the edge on the surface provided the ratio of the parameters to λ are less than some limiting values. The nature of the amplitude decay is independent of R when the depth exceeds 2λ, and independent of h when R exceeds 1.5λ. When these are below the limiting values ( h = 2λ and R = 1.5λ), the nature of the decay depends appreciably on R and h. The apparent decay in amplitude on the surface due to geometrical spreading by the diffracting edge is less than that of a cylindrical secondary wave source and decreases with increase in depth of the edge. The nature of the travel time curves of the diffracted waves near the edge depend on R /λ when the depth is within about one λ. Apparent velocity of the wave depends largely on R /λ in the zone of diffraction up to a distance of about one λ from the edge on the surface. Beyond this distance the velocity is almost the same irrespective of R /λ and depend only on h /λ. The width of the zone of diffraction caused by an edge of finite length comparable to λ is more and more narrow as the ratio of the distance of the edge on the surface to its depth increases.