Seismic velocity structure and anisotropy of the Alaska subduction zone based on surface wave tomography
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In this article, the authors used teleseismic Rayleigh waves to image large-scale variations in shear wave structure for the subducting Pacific/Yakutat slab.Abstract:
Southcentral Alaska is a complex tectonic region that transitions from subduction of Pacific crust to flat slab subduction—and collision—of overthickened Yakutat crust. Because much of the Yakutat crust has been subducted, seismic imaging is needed in order to understand the crustal and upper mantle structural framework for this active tectonic setting. Here we use teleseismic Rayleigh waves to image large-scale variations in shear wave structure. Our imaging technique employs a two-plane wave representation with finite frequency sensitivity kernels. Our 3-D isotropic model reveals several features: the subducting Pacific/Yakutat slab, slow wave speeds characterizing the onshore Yakutat collision zone, slow wave speeds of the Wrangell subduction zone, and a deep tomographic contrast at the eastern edge of the Pacific/Yakutat slab. We produce anisotropic phase velocity maps that exhibit variations in the fast direction of azimuthal anisotropy. These maps show the dominance of the Yakutat slab on the observed pattern of anisotropy. West of the Yakutat slab the fast directions are approximately aligned with the plate convergence direction. In the region of the Yakutat slab the pattern is more complicated. Along the margins of the slab the fast directions are roughly parallel to the margins. We identify notable differences and similarities with published SKS splitting measurements. Integrative modeling using 3-D anisotropy models and different seismic measurements will be needed in order to establish a detailed 3-D anisotropic velocity model for Alaska. This study provides a large-scale starting point for such an effort.read more
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Seismic anisotropy tomography: New insight into subduction dynamics
Dapeng Zhao,Sheng Yu,Xin Liu +2 more
TL;DR: P-wave anisotropy tomography is a powerful tool for mapping three-dimensional variations of azimuthal and radial seismic anisotsropy in the crust and mantle as discussed by the authors.
Journal ArticleDOI
Aseismic Deep Slab and Mantle Flow Beneath Alaska: Insight From Anisotropic Tomography
Journal ArticleDOI
Model Update May 2016: Upper‐Mantle Heterogeneity beneath North America from Travel‐Time Tomography with Global and USArray Data
Scott Burdick,Frank L. Vernon,Vladik Martynov,J. A. Eakins,Trilby Cox,Jonathan Tytell,Taimi Mulder,Malcolm White,Luciana Astiz,Gary L. Pavlis,Robert D. van der Hilst +10 more
TL;DR: In this article, the authors present the final model update, MITP_USA_2016MAY, which includes the complete set of travel-time residuals from USArray Transportable Array (TA) in the contiguous United States.
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