Strains of scattering of near-field of a point source

被引：0
作者：
Sharma M.D. [1 ]
机构：
[1] Department of Mathematics, Kurukshetra University
来源：
Journal of Earth System Science | 2004年 / 113卷 / 2期
关键词：
Near-field; Point source; Scattering; Strains; Volume inhomogeneity;
D O I：
10.1007/BF02709791
中图分类号：
学科分类号：
摘要：
Three dimensional scattering of near-field is studied for dilatation and rotation in the time domain. The perturbation method is applied to solve the equation of motion for the first order scattering from a weak inhomogeneity in an otherwise homogeneous medium. The inhomogeneity is assumed close enough to the point source so that the near-field intermediate wave is dominating over the far-field spherical P and S pulses. The integral expressions are derived to relate dilatation and rotation of scattering to the radial fluctuations of velocities and density in the inhomogeneity. These integrals are solved to calculate the strains of scattering from (a part of) an inhomogencous spherical shell of arbitrary curvature. Variable curvature may allow the shape of inhomogeneity volume element to change uniformly from spherical to rectangular. Rotation of scattering from a spherical shell is independent of P wave velocity inhomogeneity. Dilatation of scattering does not involve S wave velocity inhomogeneity but its gradient. The back scattering results are obtained as a special case. Strains are computed numerically, for hypothetical models to study the effects of various parameters viz., velocity inhomogeneity, distance of source from inhomogeneity and from receiver, and thickness of inhomogeneity. The curvature of the spherical shell is varied to study the effects of the shape of inhomogeneous volume element on scattering. © Printed in India.
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页码：247 / 257
页数：10
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共 19 条
  • [1] Aki K., Richards P.G., Quantitative Seismology, Theory and Methods, 1-2, (1980)
  • [2] Grillo R., Korneev V.A., Johnson L.R., Low frequency elastic wave scattering by all inclusion: Limits of applications, Geophys. J. Int., 120, pp. 677-692, (1995)
  • [3] Gurevich B., Sadovnichaja A.P., Lopatnikov S.L., Shapiro S.A., The Born approximation in the problem of elastic wave scattering by a spherical inhomogeneity in a fluid saturated porous media, Appl. Phys. Lett., 61, pp. 1275-1277, (1992)
  • [4] Gurevich B., Sadovnichaja A.P., Lopatnikov S.L., Shapiro S.A., Scattering of a compressional wave in a poroelastic medium by all ellipsoidal inclusion, Geophys. J. Int., 133, pp. 91-103, (1998)
  • [5] Iida M., A systematic method for analysing borehole recording to estimate the wave field in the lakebed zone of Mexico City, Bull. Seism. Soc. Am., 90, pp. 1268-1280, (2000)
  • [6] Korneev V.A., Johnson L.R., Scattering of elastic waves by a spherical inclusion-I: Theory and numerical results, Geophys. J. Int., 115, pp. 230-250, (1993)
  • [7] Leary P.C., Basement rock fracture structure from Cajon Pass, California and Siljan Ring, Sweden, borehole geophysical logs, 60th Ann. Int. Meet., pp. 153-155, (1990)
  • [8] Leary P.C., Quantifying crustal fracture heterogeneity by seismic scattering, Geophys. J. Int., 122, pp. 125-142, (1995)
  • [9] Leary P.C., Abercrombie R., Frequency dependent crustal scattering and absorption at 5-160 Hz from coda decay observed at 2.5 km depth, Geophys. Res. Lett., 21, pp. 1683-1686, (1994)
  • [10] Rikitake T., Current Research in Earthquake Prediction, I. Developments in Earth and Planetary Sciences, (1981)
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