Stochastic dispersion of short-period P-waves due to scattering and multipathing

McLaughlin, K. L.; Anderson, Lisa M.

doi:10.1111/j.1365-246x.1987.tb05202.x

Cited by 36 publications

(15 citation statements)

References 33 publications

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“…Examining long propagation-distance P-wave signals from an explosion recorded at the NORSAR array, McLaughlin and Anderson (1987) found that 5 Hz-band signals arrive later than those in the 1 Hz band. Comparison with numerical simulations of P-wave propagation through a random medium, they interpreted the observed velocity dispersion to be caused by randomness having multiple correlation distances.…”

Section: Envelopes Of Teleseismic P-wavesmentioning

confidence: 98%

Seismic Wave Propagation and Scattering in the Heterogeneous Earth : Second Edition

Sato¹,

Fehler²,

Maeda³

2012

471

385

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Scattering due to randomly distributed small-scale heterogeneities in the earth significantly changes seismic waveforms of local earthquakes especially for short periods. Scattering excites long lasting coda waves after the direct arrival and broadens the apparent duration of oscillation with increasing travel distance much longer than the source duration time. Models of propagation through deterministic structures such as those with horizontally uniform velocity layers cannot explain those observed phenomena. Our goal in writing this book is to put a focus on the phenomena of seismic wave scattering by distributed heterogeneities in the earth, especially in the lithosphere, where stochastic treatment is essential to describe both heterogeneous media and wave propagation through them. Stochastic approaches and deterministic approaches are complementary for the construction of a unified image of the earth's structure.Keiiti Aki was a distinguished pioneer who extensively developed various stochastic methods for short-period seismology. His strong encouragement and continuous support for us were essential in motivating us to write the first edition of this book. Before Kei passed away in 2005, he kindly cited our book when he argued for the importance of the study on seismic wave scattering caused by small-scale heterogeneity in his letter to V. I. Keilis-Borok, ". . . To a geodynamicist, the earth's property is smoothly varying within bodies bounded by large-scale interfaces. Most seismologists also belong to this "smooth earth club," because once you start with an initial model of smooth earth your data usually do not require the addition of smallscale heterogeneity to your initial model. As summarized well in a recent book by Sato and Fehler (1998), the acceptance of coda waves in the data set is needed for the acceptance of small-scale seismic heterogeneity of the lithosphere. There are an increasing number of seismologists who accept it, forming the "rough earth club." I believe that you are also a member of the rough earth club, judging from the emphasis on the hierarchical heterogeneity of the lithosphere. . . . "(Aki 2009).The first edition of this book was fortunately accepted in the geophysical community as a textbook, especially for graduate students. Furthermore it has been often cited in the physics community since this book introduced various aspects of wave scattering in real heterogeneous media. During the decade following the vii viii Preface to the Second Edition publication of the first edition, there were developments in stochastic methods and analyses focusing on seismogram envelopes. Radiative transfer theory has been used not only for the study of coda envelopes but also for the analysis of whole seismogram envelopes. These studies made it possible to resolve the spatial variation of scattering strength. There have been developments in the statistical description of wave propagation in random media that reliably predict the delay of peak amplitude from the onset and the broadening of seismogr...

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Section: Envelopes Of Teleseismic P-wavesmentioning

confidence: 98%

Seismic Wave Propagation and Scattering in the Heterogeneous Earth : Second Edition

Sato¹,

Fehler²,

Maeda³

2012

471

385

View full text Add to dashboard Cite

show abstract

“…(1992). In an earlier publication, McLaughlin and Anderson (1987) showed both theoretically and empirically that scattering preferentially delays high frequencies; McCartor (1991) andFisk et. al.…”

Section: List Of Figuresmentioning

confidence: 99%

Discrimination of Earthquakes and Explosions at Regional Distances Using Complexity

Blanford¹

1993

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“…The finite-difference method has been used by several workers to study the effects of stochastic perturbations to simple velocity models Clayton, 1984, 1986;McLaughlin et al, 1986;McLaughlin and Anderson, 1987;Dougherty and Stephen, 1988;Charette, 1991;Toks6z et al, 1991]. Such studies show that stochastic scattering can appreciably alter the spectral content of the first arrival [Frankel and Clayton, 1986;Charette, 1991].…”

Section: The Effect Of Deterministic Scatteringmentioning

confidence: 99%

“…Stephen [1990] examined acoustic benchmark solutions for a perfect wedge, a lossless penetrable wedge, and a plane-parallel waveguide. Finite-difference studies of complex media have dealt extensively with the scattering from random media Clayton, 1984, 1986;McLaughlin et al, 1986;McLaughlin and Anderson, 1987;Dougherty and Stephen, 1988;Charrette, 1991;Toksdz et al, 1991]. However, such studies have generally been limited to mean velocity perturbations of 5-20%, values significantly smaller than the variations in the magma chamber model (Figure 3.3).…”

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confidence: 99%

The seismic attenuation structure of the East Pacific Rise

Wilcock¹

1992

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Studies of seismic propagation through oceanic crust have contributed enormously to our understanding of the generation and evolution of oceanic crust. However, such work has largely been confined to the seismic velocity structure. In this thesis we present results from a study of seismic attenuation using a data set collected for three-dimensional tomographic imaging of a fast-spreading ridge. The experiment location at 9 0 30'N on the East Pacific Rise is the site of a strong mid-crustal seismic reflector which has been inferred to be the roof of a small axial magma chamber at about 1.6 km depth.A spectral method is used to estimate t*, a measure of the integrated attenuation along a wave path. Such a method assumes that the dominant frequency-dependent component of propagation is intrinsic attenuation. A logarithmic parameterization is then used to invert t* measurements for Q-I structure assuming that the velocity structure is given from earlier studies. To evaluate the method of Q tomography a full-waveform finitedifference technique which does not include attenuation is used to calculate solutions for seismic propagation through a two-dimensional velocity model. The results show a complex pattern of seismic propagation in the vicinity of the axial magma chamber. The first arrival always passes above the magma chamber. However, for paths of significant length that cross the rise axis the amplitude of this arrival is very small, and the first phase with significant amplitude is a diffraction below the magma chamber. High-amplitude Moho turning and PP arrivals may also be important secondary arrivals. Synthetic inversions show the importance of selecting time windows for power spectral estimation which are dominated by a single phase and of using wave paths which closely corresponds to that of the selected phase.A comparison of the finite difference solutions and the predictions of the a twodimensional, exact ray-tracing algorithm with record sections obtained during the tomography experiment significantly improves our understanding of seismic propagation across the East Pacific Rise. The results enable an objective choice of the position and length of the time window for t* estimation. Moreover, additional constraints are incorporated into an approximate three-dimensional ray-tracing algorithm used in the inversion so that the wave paths more closely correspond to those of the desired phase. The full data set to be inverted comprises about 3500 t* estimates and includes crustal paths which do not cross the rise axis, diffractions above and below the axial magma chamber, and Moho-turning phases. Wave paths for the Moho-turning phases cross the rise axis at a wide range of lower crustal depths.The Q-1 models resulting from two-dimensional and three-dimensional tomographic inversions show that the attenuation of seismic waves on the East Pacific Rise is dominated by two regions of low Q; one in the upper 1 km of crust, and one at depths greater than about 2 km below the rise axis. While the data do not ...

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Stochastic dispersion of short-period P-waves due to scattering and multipathing

Cited by 36 publications

References 33 publications

Seismic Wave Propagation and Scattering in the Heterogeneous Earth : Second Edition

Seismic Wave Propagation and Scattering in the Heterogeneous Earth : Second Edition

Discrimination of Earthquakes and Explosions at Regional Distances Using Complexity

The seismic attenuation structure of the East Pacific Rise

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