Shear-wave splitting measurements — Problems and solutions

Vecsey, Luděk; Plomerová, Jaroslava; Babuška, Vladislav

doi:10.1016/j.tecto.2008.01.021

Cited by 117 publications

(80 citation statements)

References 33 publications

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“…This method utilizes a grid search approach to identify the pair of splitting parameters (/, dt) which best minimizes the amount of energy on the transverse component (equivalently, which best linearizes the corrected particle motion) when the effect of splitting is accounted for. The method can be applied either to the horizontal components, rotated into a radial (R) and transverse (T) coordinate system (where the so-called radial component corresponds to the backazimuthal direction for core phases or to the initial polarization direction for direct S waves), or to the Q-T components in a ray-coordinate based L-Q-T coordinate system (Sileny and Plomerova 1996;Vecsey et al 2008). For perfectly vertical incidence, the two coordinate systems are equivalent.…”

Section: The Transverse Component Minimization Methodsmentioning

confidence: 99%

“…They highlight the observation that the cross-correlation method yields / estimates that are nearly 45°off when the incoming polarization is very close to a null direction; this problem is exacerbated for noisy data . The transverse component minimization method is also known to yield inaccurate estimates (often with unreasonably large dt values) in this situation (e.g., Savage 1999;Long and van der Hilst 2005b;Vecsey et al 2008). Finally, Vecsey et al (2008) recently carried out a study of synthetic and real SKS data comparing the transverse component minimization method, the closely related eigenvalue method, and the cross-correlation method.…”

Section: Synthetic Datamentioning

confidence: 99%

“…The transverse component minimization method is also known to yield inaccurate estimates (often with unreasonably large dt values) in this situation (e.g., Savage 1999;Long and van der Hilst 2005b;Vecsey et al 2008). Finally, Vecsey et al (2008) recently carried out a study of synthetic and real SKS data comparing the transverse component minimization method, the closely related eigenvalue method, and the cross-correlation method. They argue that the transverse component minimization method is most robust for noisy data and recommend a set of best practices related to each measurement method.…”

Section: Synthetic Datamentioning

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: The Transverse Component Minimization Methodsmentioning

confidence: 99%

Section: Synthetic Datamentioning

confidence: 99%

Section: Synthetic Datamentioning

confidence: 99%

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

2009

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“…Reviews of methodologies are presented in, for example, Savage (1999) and Fouch and Rondenay (2006). According to Vecsey et al (2008), the transverse energy minimization approach yields more stable solutions than other techniques.…”

Section: Introductionmentioning

confidence: 99%

The Use of Direct Shear Waves in Quantifying Seismic Anisotropy: Exploiting Regional Arrays

Eken¹,

Tilmann²

2014

Bulletin of the Seismological Society of America

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To overcome the potential contamination of the direct S waves by sourceside anisotropy in shear-wave-splitting analysis, we describe a new approach that we call the reference station technique. The technique utilizes direct shear waves recorded at a station pair and depends on maximizing the correlation between the seismic traces at reference and target stations after correcting the reference station for known receiverside anisotropy and the target stations for arbitrary splitting parameters probed via a grid search. The algorithm also provides a delay time between both stations caused, for example, by isotropic heterogeneities. Synthetic tests demonstrate the stability of the estimated parameters, even where variability in near-surface properties (thickness and velocity of sediment layer) exists. We applied the reference station technique to data from seismic experiments at the northern margin of Tibet. Average splitting parameters obtained from the analysis of direct S-wave results are consistent with those obtained from previous SKS splitting measurements. Where differences exist, shear-wave fast polarization estimates resolved from direct S indicate a higher degree of internal consistency for closely spaced stations than those derived from SKS. This is probably due to the much larger number of direct S waves available for splitting measurements compared to SKS for the same observational period, resulting in higher quality measurements. We also demonstrate the ability of the technique to provide improved splitting measurements for temporary stations by following a bootstrap approach in which only a few stations with well-constrained SKS splitting parameters are used as seeds to determine the splitting parameters of a large array in an iterative manner. In addition, the S measurements sample the anisotropic layer with different angles of incidence and back azimuths, thus potentially providing additional constraints on more complicated anisotropic structures, and the interstation delay times could be used for tomographic studies to reduce the bias from anisotropic structure.Online Material: Multisplit software package (C++) with instructions.

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“…By analyzing lateral and azimuthal variations of the splitting parameters and by inverting these variations, jointly with P anisotropic parameters, we can model a lithosphere fabric. Joint inversion/interpretation of independent data (e.g., deviations in travel times, shear-wave splitting, surface-wave dispersions, receiver functions) reduces a set of potential models which could explain the observations and thus favour more realistic solutions (Fouch and Rondenay 2006;Vecsey et al 2008). (P) waves and from shear-wave (SKS) splitting.…”

Section: Mapping Of Seismic Anisotropymentioning

confidence: 99%

Mantle lithosphere control of crustal tectonics and magmatism of the western Ohře (Eger) Rift

Babuška¹,

Plomerová²

2012

J. Geosci.

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This paper summarizes our recent research on the relationship between tectonics of the mantle lithosphere and of the upper crust in the western Bohemian Massif. The rejuvenated Variscan junction of three mantle domains, the Saxothuringian, Moldanubian and Teplá-Barrandian, delimited by different orientation of seismic anisotropy reflecting a consistent fossil olivine orientation and belonging to originally separated microplates, plays important role in the crustal architecture of the region. The crust above the mantle junction is the most active part of the BM characterized by periodic earthquake swarms and mofettes emitting gases of mantle origin. Detected offsets of surface boundaries of the three units from their mantle counterparts indicate a detachment of the rigid upper crust from the mantle lithosphere. Locations of major tectonic features like the Ohře (Eger) Rift, the West Bohemian Shear Zone and the Mariánské Lázně Fault were probably predisposed by the boundaries of the mantle lithosphere domains. We have suggested that the sublithospheric mantle of the western BM acted as a major provider for heat and partial melts and the Variscan mantle boundaries served as magma conduits for the late-orogenic granitic magmatism and, after their rejuvenation, also for the Cenozoic volcanism. Similarly, the boundaries may have pre-determined the subsequent locations of sedimentary basins. It is possible that also in other regions some of these so called intra-plate phenomena can be related to partly healed up and later rejuvenated microplate boundaries.

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Shear-wave splitting measurements — Problems and solutions

Cited by 117 publications

References 33 publications

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

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

The Use of Direct Shear Waves in Quantifying Seismic Anisotropy: Exploiting Regional Arrays

Mantle lithosphere control of crustal tectonics and magmatism of the western Ohře (Eger) Rift

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