Shear-wave velocity and anisotropy in rocks: A laboratory study

Tao, Guo; King, M. S.

doi:10.1016/0148-9062(90)92710-v

Cited by 57 publications

(29 citation statements)

References 15 publications

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“…The anisotropic attenuation of rocks is found from ultrasonic observation in the laboratory (Tao and King, 1990;Best et al, 2007;Zhubayev et al, 2016) and from a field seismic survey (Carter and Kendall, 2006;Clark et al, 2009;Behura et al, 2012;Shekar and Tsvankin, 2012). Because waves tend to exhibit anisotropic behavior as a result of the natural thin layering of the earth, we would expect the same waves to experience an anisotropic attenuation for the same reason.…”

Section: Introductionmentioning

confidence: 99%

An acoustic eikonal equation for attenuating transversely isotropic media with a vertical symmetry axis

Hao

Alkhalifah

2017

GEOPHYSICS

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Seismic-wave attenuation is an important component of describing wave propagation. Certain regions, such as gas clouds inside the earth, exert highly localized attenuation. In fact, the anisotropic nature of the earth induces anisotropic attenuation because the quasi P-wave dispersion effect should be profound along the symmetry direction. We have developed a 2D acoustic eikonal equation governing the complex-valued traveltime of quasi P-waves in attenuating, transversely isotropic media with a vertical-symmetry axis (VTI). This equation is derived under the assumption that the complex-valued traveltime of quasi P-waves in attenuating VTI media are independent of the S-wave velocity parameter υ S0 in Thomsen's notation and the S-wave attenuation coefficient A S0 in Zhu and Tsvankin's notation. We combine perturbation theory and Shanks transform to develop practical approximations to the acoustic attenuating eikonal equation, capable of admitting an analytical description of the attenuation in homogeneous media. For a horizontal-attenuating VTI layer, we also derive the nonhyperbolic approximations for the real and imaginary parts of the complex-valued reflection traveltime. These equations reveal that (1) the quasi SV-wave velocity and the corresponding quasi SV-wave attenuation coefficient given as part of Thomsen-type notation barely affect the ray velocity and ray attenuation of quasi P-waves in attenuating VTI media; (2) combining the perturbation method and Shanks transform provides an accurate analytic eikonal solution for homogeneous attenuating VTI media; (3) for a horizontal attenuating VTI layer with weak attenuation, the real part of the complex-valued reflection traveltime may still be described by the existing nonhyperbolic approximations developed for nonattenuating VTI media, and the imaginary part of the complex-valued reflection traveltime still has the shape of nonhyperbolic curves. In addition, we have evaluated the possible extension of the proposed eikonal equation to realistic attenuating media, an alternative perturbation solution to the proposed eikonal equation, and the feasibility of applying the proposed nonhyperbolic equation for the imaginary part of the complex-valued traveltime to invert for interval attenuation parameters.

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Section: Introductionmentioning

confidence: 99%

An acoustic eikonal equation for attenuating transversely isotropic media with a vertical symmetry axis

Hao

Alkhalifah

2017

GEOPHYSICS

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“…The pulse train bandwidths are as follows: P-wave, 500 to 900 kHz; S-wave, 300 to 700 kHz. The time-of-flight method, as described by Tao and King (1990), was used to determine the P-and S-wave velocities. A hydrostatic stress of 1 MPa was first applied with the hydraulic pressure system to allow the lead foil disks to bed down and to permit unequivocal picks for S-wave arrivals.…”

Section: Acoustic Propertiesmentioning

confidence: 99%

Parameters Controlling Acoustic Properties of Carbonate and Volcaniclastic Sediments at Sites 866 and 869

Ivanov¹

1995

Proceedings of the Ocean Drilling Program, 143 Scientific Results

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Comparison of the acoustic and index properties with the petrographic character of 125 brine-saturated carbonate and volcaniclastic rocks from Sites 866 and 869 indicates that porosity is the dominant parameter influencing P-and S-wave velocity and acoustic impedance. Porosity in the mid-Cretaceous platform carbonates (Site 866) is controlled by diagenetic alteration, rather than primary depositional texture. Replacement and cementation by dolomite yields the highest acoustic velocities. Similarly, porosity in the volcaniclastics (Site 869) is controlled by diagenetic alteration of components and partial replacement and cementing by zeolite.The density-velocity relationship of the carbonates shows excellent correlation with Gardners curve for limestone. The general Gardners curve, however, underestimates the velocities of the volcaniclastics. Laboratory porosity-velocity trends of the carbonates are consistently 5% to 20% higher than those predicted by the time-average equation using the correct matrix velocities. Similar crossplots for the volcaniclastics show a division into two distinct subgroups, each corresponding to a time-average equation with a different matrix velocity, which suggests that progressive diagenetic alteration of the volcaniclastics has decreased the matrix velocity. The VjJV s ratios of the carbonates do not discriminate mineralogic composition. Laboratory measurements, under effective pressure simulating in situ conditions, are 5% to 25% higher than analyses of velocity made aboard JOIDES Resolution under atmospheric pressure.The carbonates at Site 866 have a considerably wider range of acoustic impedance than the basalt. As a consequence, the contact between the carbonate succession and the underlying basalt basement in many drowned Cretaceous guyots of the equatorial Pacific Ocean may be difficult to image seismic-reflection profiles.

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“…This type of azimuthal variation in 1/ Q Lg has been observed in the western United States [ Sutton et al , 1967; Phillips et al , 2009], Tien Shan [ Martynov et al , 1999], and southern Tibet [ Reese et al , 1999]. Experimental and theoretical studies have suggested that Q could be azimuthal‐dependent and typically related to velocity anisotropy [ Tao and King , 1990; Červený and Pšenčík , 2008]. Similar correlations were derived and widely applied for azimuthal velocity anisotropy of body and surface waves [ Backus , 1965; Smith and Dahlen , 1973; Crampin , 1977].…”

Section: Introductionmentioning

confidence: 73%

Azimuthal anisotropy of Lg attenuation in eastern Tibetan Plateau

Bao¹,

Sandvol²,

Chen³

et al. 2012

J. Geophys. Res.

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[1] The Q of seismic phase Lg is measured to approach the crustal Q b , which can be used to infer crustal rheology. A reverse two-station/event method is used to measure the interstation Q Lg , which theoretically eliminates effects from the source and site response. Strong azimuthal anisotropy of 1/Q Lg in northern Tibet is observed, which approximately correlates with the seismic velocity anisotropy observed using both surface waves and teleseismic S waves. Both the intrinsic and scattering attenuation contribute the isotropic Q, whereas the anisotropic Q may be associated with the fractures and faults in the crust. Strong 1/Q Lg is observed in the northwestern Songpan-Ganzi fold belt, where the high-Q directions correspond with the orientations of major strike-slip faults. Intrinsic and scattering Q values are estimated for different tectonic terranes in eastern Tibetan Plateau. The intrinsic Q values are approximately 500 in the northern Tibetan Plateau, which suggests a hot ($700 C) crust, consistent with low seismic velocity measurements. Our result suggests that the crust of northwestern Songpan-Ganzi fold belt may be hotter than that of the Qiangtang terrane, which may be related to the strain heating along the major strike slip fault zones that dominate the northernmost Tibet.

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Shear-wave velocity and anisotropy in rocks: A laboratory study

Cited by 57 publications

References 15 publications

An acoustic eikonal equation for attenuating transversely isotropic media with a vertical symmetry axis

An acoustic eikonal equation for attenuating transversely isotropic media with a vertical symmetry axis

Parameters Controlling Acoustic Properties of Carbonate and Volcaniclastic Sediments at Sites 866 and 869

Azimuthal anisotropy of Lg attenuation in eastern Tibetan Plateau

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