Length scales, patterns and origin of azimuthal seismic anisotropy in the upper mantle as mapped by Rayleigh waves
We measure the degree of consistency between published models of azimuthal seismic anisotropy from surface waves, focusing on Rayleigh wave phase-velocity models. Some models agree up to wavelengths of ∼2000 km, albeit at small values of linear correlation coefficients. Others are, however, not well...
| मुख्य लेखकों: | , , , |
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| स्वरूप: | Journal article |
| भाषा: | English |
| प्रकाशित: |
2007
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| _version_ | 1826277607552843776 |
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| author | Becker, T Ekstroem, G Boschi, L Woodhouse, J |
| author_facet | Becker, T Ekstroem, G Boschi, L Woodhouse, J |
| author_sort | Becker, T |
| collection | OXFORD |
| description | We measure the degree of consistency between published models of azimuthal seismic anisotropy from surface waves, focusing on Rayleigh wave phase-velocity models. Some models agree up to wavelengths of ∼2000 km, albeit at small values of linear correlation coefficients. Others are, however, not well correlated at all, also with regard to isotropic structure. This points to differences in the underlying data sets and inversion strategies, particularly the relative 'damping' of mapped isotropic versus anisotropic anomalies. Yet, there is more agreement between published models than commonly held, encouraging further analysis. Employing a generalized spherical harmonic representation, we analyse power spectra of orientational (2ψ) anisotropic heterogeneity from seismology. We find that the anisotropic component of some models is characterized by stronger short-wavelength power than the associated isotropic structure. This spectral signal is consistent with predictions from new geodynamic models, based on olivine texturing in mantle flow. The flow models are also successful in predicting some of the seismologically mapped patterns. We substantiate earlier findings that flow computations significantly outperform models of fast azimuths based on absolute plate velocities. Moreover, further evidence for the importance of active upwellings and downwellings as inferred from seismic tomography is presented. Deterministic estimates of expected anisotropic structure based on mantle flow computations such as ours can help guide future seismologic inversions, particularly in oceanic plate regions. We propose to consider such a priori information when addressing open questions about the averaging properties and resolution of surface and body wave based estimates of anisotropy. © 2007 The Authors Journal compilation © 2007 RAS. |
| first_indexed | 2024-03-06T23:31:27Z |
| format | Journal article |
| id | oxford-uuid:6c299e2a-9174-4f27-be4b-9538c7e01de8 |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-06T23:31:27Z |
| publishDate | 2007 |
| record_format | dspace |
| spelling | oxford-uuid:6c299e2a-9174-4f27-be4b-9538c7e01de82022-03-26T19:09:02ZLength scales, patterns and origin of azimuthal seismic anisotropy in the upper mantle as mapped by Rayleigh wavesJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:6c299e2a-9174-4f27-be4b-9538c7e01de8EnglishSymplectic Elements at Oxford2007Becker, TEkstroem, GBoschi, LWoodhouse, JWe measure the degree of consistency between published models of azimuthal seismic anisotropy from surface waves, focusing on Rayleigh wave phase-velocity models. Some models agree up to wavelengths of ∼2000 km, albeit at small values of linear correlation coefficients. Others are, however, not well correlated at all, also with regard to isotropic structure. This points to differences in the underlying data sets and inversion strategies, particularly the relative 'damping' of mapped isotropic versus anisotropic anomalies. Yet, there is more agreement between published models than commonly held, encouraging further analysis. Employing a generalized spherical harmonic representation, we analyse power spectra of orientational (2ψ) anisotropic heterogeneity from seismology. We find that the anisotropic component of some models is characterized by stronger short-wavelength power than the associated isotropic structure. This spectral signal is consistent with predictions from new geodynamic models, based on olivine texturing in mantle flow. The flow models are also successful in predicting some of the seismologically mapped patterns. We substantiate earlier findings that flow computations significantly outperform models of fast azimuths based on absolute plate velocities. Moreover, further evidence for the importance of active upwellings and downwellings as inferred from seismic tomography is presented. Deterministic estimates of expected anisotropic structure based on mantle flow computations such as ours can help guide future seismologic inversions, particularly in oceanic plate regions. We propose to consider such a priori information when addressing open questions about the averaging properties and resolution of surface and body wave based estimates of anisotropy. © 2007 The Authors Journal compilation © 2007 RAS. |
| spellingShingle | Becker, T Ekstroem, G Boschi, L Woodhouse, J Length scales, patterns and origin of azimuthal seismic anisotropy in the upper mantle as mapped by Rayleigh waves |
| title | Length scales, patterns and origin of azimuthal seismic anisotropy in the upper mantle as mapped by Rayleigh waves |
| title_full | Length scales, patterns and origin of azimuthal seismic anisotropy in the upper mantle as mapped by Rayleigh waves |
| title_fullStr | Length scales, patterns and origin of azimuthal seismic anisotropy in the upper mantle as mapped by Rayleigh waves |
| title_full_unstemmed | Length scales, patterns and origin of azimuthal seismic anisotropy in the upper mantle as mapped by Rayleigh waves |
| title_short | Length scales, patterns and origin of azimuthal seismic anisotropy in the upper mantle as mapped by Rayleigh waves |
| title_sort | length scales patterns and origin of azimuthal seismic anisotropy in the upper mantle as mapped by rayleigh waves |
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