Measurement of phase fluctuations for transmitted waves in random media

[1] Transmission fluctuations of log-amplitude and phase can be used to construct coherence functions to infer the statistical characteristics of crustal and mantle small-scale heterogeneities. Recent numerical simulations of wave propagation in random media have revealed an apparent discrepancy between simulations and theory for phase coherence functions. In this paper, we show that the reported discrepancy is a result of the inappropriate phase estimates adopted in some literature. Using unwrapped phase fluctuations, instead of estimates of the fluctuations obtained by picking first arrivals by the threshold method, we find that the theory and the results derived from finite difference simulations are consistent. The method of first arrival picking does not yield adequate estimates of phase fluctuation due to the scattering dispersion of waves in the random medium. Phase unwrapping is viable and allows correct inference of medium properties.

[1]  Sri Widiyantoro,et al.  Global seismic tomography: A snapshot of convection in the Earth: GSA Today , 1997 .

[2]  Wu Ru-Shan.  Attenuation of short period seismic waves due to scattering , 1982 .

[3]  Keiiti Aki,et al.  Scattering of P waves under the Montana Lasa , 1973 .

[4]  John C. VanDecar,et al.  Determination of teleseismic relative phase arrival times using multi-channel cross-correlation and least squares , 1990 .

[5]  Ru-Shan Wu,et al.  The perturbation method in elastic wave scattering , 1989 .

[6]  Robert Patton Leland,et al.  Wave propagation in a random medium , 1989 .

[7]  Wave propagation in one dimensional inhomogeneous elastic media. , 1979 .

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

[9]  B. Kennett,et al.  Stochastic features of scattering , 2005 .

[10]  T. Lay,et al.  Modern Global Seismology , 1995 .

[11]  Xiao‐Bi Xie,et al.  Numerical tests of stochastic tomography , 1991 .

[12]  J. Hudson,et al.  RESEARCH PAPERS : Statistical inversion of controlled-source seismic data using parabolic wave scattering theory , 2002 .

[13]  Keiiti Aki,et al.  General coherence functions for amplitude and phase fluctuations in a randomly heterogeneous medium , 1991 .

[14]  Alan G. Jones,et al.  Spectral analyses of the KTB sonic and density logs using robust nonparametric methods , 1997 .

[15]  Ru-Shan Wu,et al.  Transmission fluctuations across an array and heterogeneities in the crust and upper mantle , 1990 .

[16]  Nature and origin of upper crustal seismic velocity fluctuations and associated scaling properties: Combined stochastic analyses of KTB velocity and lithology logs , 1999 .

[17]  José Tribolet,et al.  A new phase unwrapping algorithm , 1977 .

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

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

[20]  McSween Hy,et al.  Evidence for Life in a Martian Meteorite , 1997 .

[21]  V. I. Tatarskii.  The effects of the turbulent atmosphere on wave propagation , 1971 .