The phase screen method for vector elastic waves

A phase screen method for vector elastic waves is developed. The method allows rapid calculation of the propagation of elastic waves for problems where backscatter is small; only forward propagation is included in the analysis. The method can be used for propagation through either deterministic or stochastic media. The work described here generalizes existing phase screen methods for scalar waves, accounting for the difference in phase velocities of the transverse and longitudinal polarizations. The method is tested on a two-dimensional problem, whose exact solution is also computed, for constant Poisson ratios. Synthetic seismograms for two-dimensional random media using this method are compared with existing finite difference synthetics. An important use of the method is to estimate the rate of interconversion of S and P waves in terms of the energy flux to analyze the effectiveness of potential discrimination techniques.

[1]  Robert W. Clayton,et al.  Finite difference simulations of seismic scattering: Implications for the propagation of short‐period seismic waves in the crust and models of crustal heterogeneity , 1986 .

[2]  K. R. Kelly,et al.  SYNTHETIC SEISMOGRAMS: A FINITE ‐DIFFERENCE APPROACH , 1976 .

[3]  L. Knopoff,et al.  Frequency Dependence of Amplitudes of Scattered Elastic Waves , 1967 .

[4]  P-SV resonances in irregular low-velocity surface layers , 1985 .

[5]  L. M. Anderson,et al.  Stochastic dispersion of short-period P-waves due to scattering and multipathing , 1987 .

[6]  P. Richards.  Weakly coupled potentials for high-frequency elastic waves in continuously stratified media , 1974, Bulletin of the Seismological Society of America.

[7]  Charles Macaskill,et al.  Computer Simulation of Two-dimensional Random Wave Propagation , 1984 .

[8]  R. Dashen.  Path integrals for waves in random media , 1977 .

[9]  E. N. Bramley,et al.  The accuracy of computing ionospheric radio-wave scintillation by the thin-phase-screen approximation , 1977 .

[10]  D. Knepp.  Multiple phase-screen calculation of the temporal behavior of stochastic waves , 1983, Proceedings of the IEEE.

[11]  R. Buckley,et al.  Diffraction by a random phase-changing screen: A numerical experiment , 1975 .

[12]  J A Ratcliffe,et al.  Investigation of molecular motions in supercooled liquids by Mossbauer scattering D C Champeney and F W D Woodhams Some Aspects of Diffraction Theory and their Application to the Ionosphere , 1956 .

[13]  E. S. Husebye,et al.  Joint interpretation of P‐wave time and amplitude anomalies in terms of lithospheric heterogeneities , 1978 .

[14]  S. Flatté,et al.  Small-scale structure in the lithosphere and asthenosphere deduced from arrival time and amplitude fluctuations at NORSAR , 1988 .

[15]  K. Aki,et al.  Elastic wave scattering by a random medium and the small‐scale inhomogeneities in the lithosphere , 1985 .

[16]  Robert W. Clayton,et al.  A finite-difference simulation of wave propagation in two-dimensional random media , 1984 .

[17]  H. Sato.  Attenuation and envelope formation of three‐component seismograms of small local earthquakes in randomly inhomogeneous lithosphere , 1984 .

[18]  David J. Thomson.  Wide-angle parabolic equation solutions to two range-dependent benchmark problems , 1990 .

[19]  J. Hudson.  Scattered Waves in the Coda of P , 1977 .

[20]  K. Budden,et al.  Diffraction by a Screen Causing Large Random Phase Fluctuations , 1962, Mathematical Proceedings of the Cambridge Philosophical Society.

[21]  R. M. Alford,et al.  ACCURACY OF FINITE‐DIFFERENCE MODELING OF THE ACOUSTIC WAVE EQUATION , 1974 .

[22]  S. Flatté,et al.  Intensity images and statistics from numerical simulation of wave propagation in 3-D random media. , 1988, Applied optics.

[23]  Paul G. Richards,et al.  Quantitative Seismology: Theory and Methods , 1980 .

[24]  C. Langston.  Scattering of teleseismic body waves under Pasadena, California , 1989 .

[25]  J. A. Hudson,et al.  Scattering of Elastic Waves by Small Inhomogeneities , 1964 .