Diffusion of seismic energy in the near range

Wesley, J. P.

doi:10.1029/jz070i020p05099

Cited by 72 publications

(27 citation statements)

References 14 publications

(9 reference statements)

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“…This conclusion has been confirmed by later research (Dainty et al, 1974a;Dainty < d Toks6z, 1977;Nakamura, 1976Nakamura, , 1977bPines, 1973). The following review is based on these papers; research on scattering effects in terrestrial seismograms has also been done (Aki, 1969(Aki, , 1973Aki and Chouet, 1975;Wesley, 1965;Knopoff and Hudson, 1964).…”

Section: Seismogram Characteristicsmentioning

confidence: 99%

Lunar seismology: The internal structure of the Moon

Goins¹,

Dainty²,

Toksöz³

1981

J. Geophys. Res.

147

104

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Tables A1–A4 and Figures A1–A3 are available with entire articleon microfiche. Order from American Geophysical Union, 2000 Florida Avenue, N.W., Washington, D.C. 20009. Document J81‐003;$1.00. Payment must accompany order. The arrival times of direct P and S waves, measured on seismograms recorded from natural lunar seismic events, have been analyzed using linearized inversion and parameter search methods to simultaneously determine event locations, origin times, and structural parameters (seismic velocities). Polarization‐filtered record section plots are correlated with theoretical travel time curves to identify later phases and obtain additional structural and velocity information. Shear wave amplitudes plotted as a function of distance provide data on the existence and magnitude of seismic velocity gradients in the interior. These studies are used to delineate the structure of the moon below the crust to a depth of about 1100 km. This structure has been divided into an upper and a lower mantle. The upper mantle, from 60‐ to 400‐km depth, has average seismic wave velocities of Vp = 7.70 ±0.15 km/s and Vs = 4.45 ± 0.05 km/s with corresponding Q values (taken from the literature) of Qp ∼ 5000 and Qs ∼ 3000. The shear wave velocity decreases with a negative gradient of at most −6 × 10−4 km/s/km, implying a Vs variation of from 4.57 km/s at 60‐km depth to 4.37 km/s at 400‐km depth; this decrease can be accounted for by increasing temperature, and so no major compositional gradient is required in the upper mantle. A small negative P wave velocity gradient may also be present. Between 400‐ and 480‐km depth there is a transition zone with a sharply decreasing shear wave velocity and possibly an accompanying small decrease in Vp. The dominant shear velocity decrease may occur at a 480‐km interface and may represent a compositional change, although the effects of increased temperature cannot be totally ruled out. The lower mantle extends from 480‐km depth to at least 1100‐km depth; few seismic waves recorded by the lunar network penetrate below 1100 km. The average velocities are Vp = 7.6 ± 0.6 km/s and Vs = 4.2 ± 0.1 km/s. Q values (taken from the literature) are Qp ∼ 1500 and Qs ∼ 1000. Below 1100 km there is some indication that the attenuation may increase still further for shear waves, with Qs dropping to a few hundreds or less. This seismic model of the moon is well constrained, with uncertainties on the above values given explicitly by the analysis methods, and so it serves as a strong control on the present‐day lunar compositional and thermal structure.

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Section: Seismogram Characteristicsmentioning

confidence: 99%

Lunar seismology: The internal structure of the Moon

Goins¹,

Dainty²,

Toksöz³

1981

J. Geophys. Res.

147

104

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“…The diffusion model has been used with success to characterize a wide range of wave phenomena in strongly scattering media. [2][3][4][5][6] In this model, wave energy transport acquires a diffusive character, e.g., wave energy is transported in a process similar to heat diffusion. In medical imaging, for example, diffusing near-infrared light has been used to image localized heterogeneities of tissue.…”

Section: Introductionmentioning

confidence: 99%

Time-lapse travel time change of multiply scattered acoustic waves

Pacheco

Snieder

2005

The Journal of the Acoustical Society of America

172

162

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Existing techniques in correlation spectroscopy, such as coda wave interferometry and diffusing acoustic wave spectroscopy, determine the average motion of scatterers or change in the propagation velocity from the temporal change of multiply scattered sound. However, neither of them gives an indication of the spatial extent of the change in the medium. This study is an extension of the technique coda wave interferometry, where multiply scattered waves are used to determine the change in the wave field due to a localized perturbation in the propagation velocity. Here, the propagation of multiply scattered sound is described using the diffusion approximation, which allows the cross-correlation function of the unperturbed and perturbed wave fields to be related to the localized change in the propagation velocity. The technique is tested numerically for two-dimensional ͑2D͒ acoustic waves using synthetic seismograms calculated using finite-differences before and after a small perturbation in the propagation velocity has been introduced. Despite the relatively small size and magnitude of the change, multiple scattering greatly amplifies small perturbations, making changes in the phase or travel time of the wave field visible in the later-arriving waveforms. Potential applications of this technique include nondestructive evaluation of inhomogeneous materials and time-lapse monitoring of volcanoes and highly heterogeneous reservoirs.

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“…Several attempts have been made in recent years based on this hypothesis. A diffusion model was proposed by WESLEY (1965), and this model was applied to the seismic wave propagations (NAKAMURA, 1976;AKI and CHOUET, 1975). AKI (1969) proposed a single back scattering model, which satisfactorily explained the time variation of the seismic energy density of the scattered waves near the epicenter.…”

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confidence: 99%

Mean free path of S-waves under the Kanto district of Japan.

Sato

1978

J,Phys,Earth

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Coda waves from local earthquakes are interpreted as single isotropic scattered waves by numerous heterogeneities distributed homogeneously and randomly in the earth. A mean free path characterizes the distribution of the scatterers in the earth. Seismograms obtained at the Iwatsuki observatory during the period between April and September, 1976 are studied. The Swave codas of 96 local earthquakes with magnitude 3.0-5.5 are analyzed, where only the S-wave to S-wave scattering is assumed. The total seismic energy of the S-waves (1-30Hz) is estimated from the earthquake magnitude by the Gutenberg-Richter formula. The mean free path of S-waves (1-30Hz) under the Kanto district of Japan is estimated to be IntroductionThere is a hypothesis that seismic coda waves of local earthquakes are incoherent scattered seismic waves from numerous heterogeneities distributed homogeneously and randomly in the earth. Several attempts have been made in recent years based on this hypothesis. A diffusion model was proposed by WESLEY (1965), and this model was applied to the seismic wave propagations (NAKAMURA, 1976;AKI and CHOUET, 1975). AKI (1969) proposed a single back scattering model, which satisfactorily explained the time variation of the seismic energy density of the scattered waves near the epicenter. This model was applied to the seismograms obtained in Japan and California and vigorous analyses were performed by Aki and his co-worker (AKI, 1973;AKI and CHOUET, 1975). SATO (1977aSATO ( , 1977b) suggested a single isotropic scattering model, which enables us to obtain a space-time distribution of the seismic energy density of the scattered body waves. Independently, surface wave scattering were studied by KOPNICHEV (1975) on the basis of the isotropic assumption in a two dimensional case.In these scattering theories, the mean free path of seismic waves characterizes the distribution of the scatterers in the earth. That is, the mean free path provides a fundamental information on the tectonic condition. The mean free paths of short period body waves were determined from the analysis of codas of only a few earthquakes with magnitude 3 by AKI and CHOUET 185

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Diffusion of seismic energy in the near range

Cited by 72 publications

References 14 publications

Lunar seismology: The internal structure of the Moon

Lunar seismology: The internal structure of the Moon

Time-lapse travel time change of multiply scattered acoustic waves

Mean free path of S-waves under the Kanto district of Japan.

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