How to relate body wave and surface wave anisotropy?

Montagner, J. P.; Griot-Pommera, Daphné Anne; Lavé, Jérôme

doi:10.1029/2000jb900015

Cited by 102 publications

(148 citation statements)

References 49 publications

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“…We note, however, that there is a discrepancy in the shear wave splitting literature regarding the commutivity of the splitting operator in the low-frequency limit. Several theoretical studies have claimed that the splitting operators do not commute even at low frequency (e.g., Savage and Silver 1993;Wolfe and Silver 1998), while other workers have asserted that in the low-frequency limit the higher-order terms that lead to this noncommutivity can be discarded (Montagner et al 2000). Until this discrepancy is resolved, results based on the assumption of commutivity should be treated with some caution.…”

Section: Integration With Other Seismological Constraintsmentioning

confidence: 91%

“…There has been some theoretical progress on how to relate shear wave splitting to P wave traveltime residuals (e.g., Plomerová et al 1996;Schulte-Pelkum and Blackman 2003) and to surface wave observations (e.g. Montagner et al 2000). Extreme care must be taken, however, to properly account for the effect of vertically varying anisotropy and in particular for the fact that the shear wave splitting operator is non-commutative (Silver and Savage 1994;Wolfe and Silver 1998); some schemes for predicting shear wave splitting in common use may fail for vertically varying anisotropy.…”

Section: Integration With Other Seismological Constraintsmentioning

confidence: 99%

“…Extreme care must be taken, however, to properly account for the effect of vertically varying anisotropy and in particular for the fact that the shear wave splitting operator is non-commutative (Silver and Savage 1994;Wolfe and Silver 1998); some schemes for predicting shear wave splitting in common use may fail for vertically varying anisotropy. In particular, the method of Montagner et al (2000) utilizes simplifying assumptions that do not account for the non-commutivity of the splitting operator at long periods. Integrating splitting observations with other seismological observables remains a significant challenge, because different observables are sensitive to anisotropy at different depths and on different length scales and properly integrating them is usually non-trivial.…”

Section: Integration With Other Seismological Constraintsmentioning

confidence: 99%

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Shear Wave Splitting and Mantle Anisotropy: Measurements, Interpretations, and New Directions

2009

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Measurements of the splitting or birefringence of seismic shear waves that have passed through the Earth's mantle yield constraints on the strength and geometry of elastic anisotropy in various regions, including the upper mantle, the transition zone, and the D 00 layer. In turn, information about the occurrence and character of seismic anisotropy allows us to make inferences about the style and geometry of mantle flow because anisotropy is a direct consequence of deformational processes. While shear wave splitting is an unambiguous indicator of anisotropy, the fact that it is typically a near-vertical path-integrated measurement means that splitting measurements generally lack depth resolution. Because shear wave splitting yields some of the most direct constraints we have on mantle flow, however, understanding how to make and interpret splitting measurements correctly and how to relate them properly to mantle flow is of paramount importance to the study of mantle dynamics. In this paper, we review the state of the art and recent developments in the measurement and interpretation of shear wave splitting-including new measurement methodologies and forward and inverse modeling techniques,-provide an overview of data sets from different tectonic settings, show how they help us relate mantle flow to surface tectonics, and discuss new directions that should help to advance the shear wave splitting field.

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Section: Integration With Other Seismological Constraintsmentioning

confidence: 91%

Section: Integration With Other Seismological Constraintsmentioning

confidence: 99%

Section: Integration With Other Seismological Constraintsmentioning

confidence: 99%

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Shear Wave Splitting and Mantle Anisotropy: Measurements, Interpretations, and New Directions

2009

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“…6b), and the SKS predictions themselves (Supplementary Fig. 6c) rely on a theory 30 that does not properly handle inclined symmetry axes and is only effective for rather long period waves.…”

Section: Resolution Issues and Model Testsmentioning

confidence: 99%

Global azimuthal seismic anisotropy and the unique plate-motion deformation of Australia

Debayle

Kennett

Priestley

2005

Nature

256

277

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International audienceDifferences in the thickness of the high-velocity lid underlying continents as imaged by seismic tomography, have fuelled a long debate on the origin of the 'roots' of continents(1-5). Some of these differences may be reconciled by observations of radial anisotropy between 250 and 300 km depth, with horizontally polarized shear waves travelling faster than vertically polarized ones(2). This azimuthally averaged anisotropy could arise from present-day deformation at the base of the plate, as has been found for shallower depths beneath ocean basins(6). Such deformation would also produce significant azimuthal variation, owing to the preferred alignment of highly anisotropic minerals(7). Here we report global observations of surface-wave azimuthal anisotropy, which indicate that only the continental portion of the Australian plate displays significant azimuthal anisotropy and strong correlation with present-day plate motion in the depth range 175 - 300 km. Beneath other continents, azimuthal anisotropy is only weakly correlated with plate motion and its depth location is similar to that found beneath oceans. We infer that the fast-moving Australian plate contains the only continental region with a sufficiently large deformation at its base to be transformed into azimuthal anisotropy. Simple shear leading to anisotropy with a plunging axis of symmetry may explain the smaller azimuthal anisotropy beneath other continents

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“…Therefore, results of crustal azimuthal anisotropy from receiver function analysis may still have some uncertainties due to the use of different methods and data selection criteria. Montagner et al (2000) derives formulas to compute the shear wave splitting time and fast axes from depthdependent G c,s and L, which provides a direct link between shear wave splitting measurements and shear wavespeed azimuthal anisotropy from surface wave data. For instance, Yao et al (2010) computed the contribution of shear wave splitting from crustal azimuthal anisotropy obtained from surface wave data and found that the thick crust in SE Tibet may contribute almost 1 s splitting time, which is close to b Depth-dependent shear wavespeed azimuthal anisotropy obtain from the NA: the black line for the magnitude of azimuthal anisotropy (K SV ) and the red bars for the direction of fast axes (U F ) in each layer (vertical for a N-S direction and horizontal for a E-W direction).…”

Section: Discussionmentioning

confidence: 99%

A method for inversion of layered shear wavespeed azimuthal anisotropy from Rayleigh wave dispersion using the Neighborhood Algorithm

Yao

2015

Earthq Sci

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Seismic anisotropy provides important constraints on deformation patterns of Earth's material. Rayleigh wave dispersion data with azimuthal anisotropy can be used to invert for depth-dependent shear wavespeed azimuthal anisotropy, therefore reflecting depth-varying deformation patterns in the crust and upper mantle. In this study, we propose a two-step method that uses the Neighborhood Algorithm (NA) for the point-wise inversion of depth-dependent shear wavespeeds and azimuthal anisotropy from Rayleigh wave azimuthally anisotropic dispersion data. The first step employs the NA to estimate depthdependent V SV (or the elastic parameter L) as well as their uncertainties from the isotropic part Rayleigh wave dispersion data. In the second step, we first adopt a difference scheme to compute approximate Rayleigh-wave phase velocity sensitivity kernels to azimuthally anisotropic parameters with respect to the velocity model obtained in the first step. Then we perform the NA to estimate the azimuthally anisotropic parameters G c /L and G s /L at depths separately from the corresponding cosine and sine terms of the azimuthally anisotropic dispersion data. Finally, we compute the depth-dependent magnitude and fast polarization azimuth of shear wavespeed azimuthal anisotropy. The use of the global search NA and Bayesian analysis allows for more reliable estimates of depth-dependent shear wavespeeds and azimuthal anisotropy as well as their uncertainties.We illustrate the inversion method using the azimuthally anisotropic dispersion data in SE Tibet, where we find apparent changes of fast axes of shear wavespeed azimuthal anisotropy between the crust and uppermost mantle.

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How to relate body wave and surface wave anisotropy?

Cited by 102 publications

References 49 publications

Shear Wave Splitting and Mantle Anisotropy: Measurements, Interpretations, and New Directions

Shear Wave Splitting and Mantle Anisotropy: Measurements, Interpretations, and New Directions

Global azimuthal seismic anisotropy and the unique plate-motion deformation of Australia

A method for inversion of layered shear wavespeed azimuthal anisotropy from Rayleigh wave dispersion using the Neighborhood Algorithm

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