Experimental study of shear-waves from shots in anisotropic media

Galperina, R. M.; Galperin, E. I.

doi:10.1111/j.1365-246x.1987.tb05243.x

Cited by 3 publications

(3 citation statements)

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“…This had been suspected in the past (Turcotte 1992), but this is now a direct correlation with other phenomena. (Hess 1964) and continents (Bamford 1977) Anisotropy observed (Crampin 1966) and calculated in higher-mode surface-wave dispersion (Crampin and King 1977) Shear-wave splitting first named (as S-wave splitting) and displayed in synthetic seismograms (Keith and Crampin 1977c) 1IWSA 1982 Observations of P-wave velocity anisotropy in field and laboratory (Artemieva and Chesnokov 1991;Brodov et al 1991;Brown et al 1991;de Parscau 1991;MacBeth 1991a, b) Elastic moduli calculated for aligned cracks (Crampin 1978(Crampin , 1984b Importance of shear-wave window above small earthquakes recognised (Evans 1984) Aligned microcracks (EDA cracks) suggested in most crustal rocks ) General behaviour of wave propagation in cracked media reviewed (Crampin 1981) Shear-wave splitting displayed in synthetic seismograms through cracked media (Crampin 1978) Shear-wave splitting observed above earthquakes in both crust (Crampin et al 1980) and upper mantle (Ando et al 1980) 2IWSA 1986 1987 Observations of P-wave anisotropy in crust Galperina and Galperin 1987) Speculation on how monitoring shear-wave splitting could predict earthquakes (Chen et al 1987) Determination of the Thomsen parameters for seismic exploration (Thomsen 1986) Double-contour integration for 3D full-wave propagation in anisotropic substrates (Taylor 1987) 3IWSA 1988 Observations of anisotropy in laboratory studies in both field and laboratory (Kaneshima 1990;Savage et al 1990;Shih and Meyer 1990) First attempts at automatic measurement of shear-wave splitting (Shih and Meyer 1990) First correlation of microcracks with fractures and directions of preferred fluid flow (Queen and Rizer 1990) Shear-wave splitting time delays seen to increase before two earthquakes ) ANISEIS programme developed for applying double-contour integration for full-wave synthetic seism...…”

Section: Discussionmentioning

confidence: 99%

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A review of a quarter century of International Workshops on Seismic Anisotropy in the crust (0IWSA–12IWSA)

Crampin

Gao

2008

J Seismol

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Section: Discussionmentioning

confidence: 99%

“…Three papers reported various observations of anisotropic effects in USSR, including the very detailed multi-azimuth reflection surveys and vertical seismic profiles (VSPs) in transverse isotropy by Galperina and Galperin (1987).…”

Section: Interpretation-aligned Cracksmentioning

confidence: 99%

A review of a quarter century of International Workshops on Seismic Anisotropy in the crust (0IWSA–12IWSA)

Crampin

Gao

2008

J Seismol

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“…It can be caused by layering as well as by intrinsic, microscopic properties of the rocks. Investigation on sediments have shown that large anisotropy effects are caused by clay (Brodov et al 1984;Galperina & Galperin 1987). The percentage of clay in a sediment is correlated with the anisotropic property of the sediment, which can hence serve as a lithology indicator (Winterstein 1986).…”

Section: Introductionmentioning

confidence: 99%

Wave Propagation In A Vertical Transversely Isotropic Medium: Field Experiment and Model Study

Kerner

Dyer

Worthington

1989

Geophysical Journal International

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A down-hole experiment was carried out in the transversely isotropic Oxford Clay outcropping in the south of England. Different moveout curves for the two shear wave types and anomalous amplitude features for the SV-wave were found in the field data. Based on velocity measurements carried out formerly at the site a model study was performed to explain the results. Phase velocity and group velocity curves computed analytically with the method of characteristics, and synthetic seismograms computed with the AlekseevMikhailenko method, are presented. The field experiment and the model studies demonstrate that the occurrence of cuspidal triangles in the qSV-wavefront is an essential feature of wave propagation in transversely isotropic media. Even for weak transversely isotropic media there is a focusing effect into the direction of the cusp which leads to prominent shear wave amplitudes in this direction. Furthermore, we examined the effect of numerical anisotropy which can contaminate the synthetic seismograms. Velocity errors are one order of magnitude higher for shear waves than for compressional waves and increase with increasing Poisson's ratio. It was found that the error can be restricted to less than 1 percent only if using a spatial sampling of three times higher than a value that would generally be regarded as sufficient in finite difference computations.

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Velocity anisotropy in shale determined from crosshole seismic and vertical seismic profile data

Winterstein

Paulsson

1990

GEOPHYSICS

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Crosshole and vertical seismic profile (VST) data made possible accurate characterization of the elastic properties, including noticeable velocity anisotropy, of a near‐surface late Tertiary shale formation. Shear‐wave splitting was obvious in both crosshole and VSP data. In crosshole data, two orthologonally polarrized shear (S) waves arrived 19 ms in the uppermost 246 ft (75 m). Vertically traveling S waves of the VSP separated about 10 ms in the uppermost 300 ft (90 m) but remained at nearly constant separation below that level. A transversely isotropic model, which incorporates a rapid increase in S-wave velocities with depth but slow increase in P-wave velocities, closely fits the data over most of the measured interval. Elastic constants of the transvesely isotropic model show spherical P- and [Formula: see text]wave velocity surfaces but an ellipsoidal [Formula: see text]wave surface with a ratio of major to minor axes of 1.15. The magnitude of this S-wave anisotropy is consistent with and lends credence to S-wave anisotropy magnitudes deduced less directly from data of many sedimentary basins.

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Experimental study of shear-waves from shots in anisotropic media

Cited by 3 publications

References 1 publication

A review of a quarter century of International Workshops on Seismic Anisotropy in the crust (0IWSA–12IWSA)

A review of a quarter century of International Workshops on Seismic Anisotropy in the crust (0IWSA–12IWSA)

Wave Propagation In A Vertical Transversely Isotropic Medium: Field Experiment and Model Study

Velocity anisotropy in shale determined from crosshole seismic and vertical seismic profile data

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