Theory and Observations – Wave Propagation in Anisotropic Media

Maupin, Valérie; Park, J.

doi:10.1016/b978-044452748-6.00007-9

Cited by 55 publications

(21 citation statements)

References 203 publications

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“…Fortunately, anisotropy with hexagonal symmetry is a proper approximation to the materials in the Earth's crust and mantle, which can reduce the number of physical parameters describing seismic anisotropy (e.g., Christensen, 1984;Park and Yu, 1993;Maupin and Park, 2007). To further simplify the problem, we can assume the hexagonal symmetry to be horizontal when the azimuthal anisotropy is concerned in SWS measurements (e.g., Crampin, 1984;Silver, 1996;Savage, 1999;Huang et al, 2011a,b;Long, 2013) and P-wave velocity studies (e.g., Hess, 1964;Backus, 1965;Raitt et al, 1969;Hearn, 1996;Eberhart-Phillips and Henderson, 2004;Zhao, 2008, 2013); whereas we can assume the hexagonal symmetry to be vertical when the radial anisotropy is concerned in the form of a Vsh/Vsv variation (Vsh and Vsv are the velocities of shear waves polarized horizontally and vertically, respectively) in surface-wave studies (e.g., Nettles and Dziewonski, 2008;Fichtner et al, 2010;Yuan et al, 2011) and in the form of a Vph/Vpv variation (Vph and Vpv are the velocities of P-waves propagating horizontally and vertically, respectively) in P-wave velocity studies (e.g., Ishise et al, 2012;.…”

Section: P-wave Anisotropy Tomography: Methodsmentioning

confidence: 99%

Seismic anisotropy tomography: New insight into subduction dynamics

2016

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Body-wave and surface-wave tomography, receiver-function imaging, and shear-wave splitting measurements have shown that seismic anisotropy and heterogeneity coexist in all parts of subduction zones, providing important constraints on the mantle flow and subduction dynamics. P-wave anisotropy tomography is a new but powerful tool for mapping three-dimensional variations of azimuthal and radial seismic anisotropy in the crust and mantle. P-wave azimuthal-anisotropy tomography has been applied widely to the Circum-Pacific subduction zones, Mainland China and North America, whereas P-wave radial-anisotropy tomography was applied to only a few areas including Northeast Japan, Southwest Japan and North China Craton. These studies have revealed complex anisotropy in the crust and mantle lithosphere associated with the surface geology and tectonics, anisotropy reflecting subduction-driven corner flow in the mantle wedge, frozen-in fossil anisotropy in the subducting slabs formed at the mid-ocean ridge, as well as olivine fabric transitions due to changes in water content, stress and temperature. Shear-wave splitting tomography methods have been also proposed, but their applications are still limited and preliminary. There is a discrepancy between the surface-wave and body-wave tomographic models in radial anisotropy of the mantle wedge beneath Japan, which is a puzzle but an intriguing topic for future studies.

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Section: P-wave Anisotropy Tomography: Methodsmentioning

confidence: 99%

Seismic anisotropy tomography: New insight into subduction dynamics

2016

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“…The use of sP depth-phase in tomography can lead us to determine the 3-D velocity structure outside a seismic network (e.g., Zhao et al, 2002Zhao et al, , 2009Mishra et al, 2003;Wang and Zhao, 2005). Layering and preferred orientations as well as seismically anisotropic materials are common in the Earth's interior, which are shown by shear-wave splitting studies (for reviews, see Savage, 1999;Helbig and Thomsen, 2005;Maupin and Park, 2007). Shearwave splitting measurements have revealed strong seismic anisotropy in the Japan subduction zone (e.g., Kaneshima, 1990;Okada et al, 1995;Nakajima and Hasegawa, 2004).…”

Section: Introductionmentioning

confidence: 98%

Mapping P-wave anisotropy of the Honshu arc from Japan Trench to the back-arc

Wang

Zhao

2010

Journal of Asian Earth Sciences

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“…Anisotropy in the Earth's upper mantle is generally attributed to lattice preferred orientation (LPO) of crystals in anisotropic minerals (e.g., olivine and pyroxene) [e.g., Hess, 1964;Savage, 1999;Mainprice, 2007]. So far, many studies have shown that the anisotropy with hexagonal symmetry is a good approximation to the rocks in the mantle [e.g., Maupin and Park, 2007;Zhao, 2009, 2013]. Previous studies of Hokkaido have generally assumed that the axis of hexagonal symmetry is horizontal and focused on P wave azimuthal anisotropy [e.g., Wang and Zhao, 2009;Liu et al, 2013;Koulakov et al, 2015].…”

Section: Introductionmentioning

confidence: 99%

P wave azimuthal and radial anisotropy of the Hokkaido subduction zone

Niu

Zhao

et al. 2016

JGR Solid Earth

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We present the first three‐dimensional P wave radial anisotropy tomography of the Hokkaido subduction zone, as well as P wave azimuthal anisotropy and S wave tomography, which are determined by inverting 298,430 P wave and 233,934 S wave arrival times from 14,245 local earthquakes recorded by 344 seismic stations. Our results reveal significant velocity heterogeneity, seismic anisotropy, and upwelling flows beneath the study region. In the mantle wedge, prominent low‐velocity (low‐V) anomalies exhibit trench‐normal fast‐velocity directions (FVDs) and a negative radial anisotropy (i.e., vertical velocity > horizontal velocity), which may reflect upwelling mantle flows. Fan‐shaped FVDs are found at depths of 65–90 km, and a detailed 3‐D mantle flow pattern is revealed, which may be caused by a combination of oblique subduction of the Pacific plate and collision of the Kuril arc with the Honshu arc beneath southern Hokkaido. The radial anisotropy changes at ~100 km depth, which may reflect variations in temperature and fluid conditions there. The subducting Pacific slab exhibits a positive radial anisotropy (i.e., horizontal velocity > vertical velocity), which may reflect the original fossil anisotropy when the Pacific plate formed at the mid‐ocean ridge.

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Theory and Observations – Wave Propagation in Anisotropic Media

Cited by 55 publications

References 203 publications

Seismic anisotropy tomography: New insight into subduction dynamics

Seismic anisotropy tomography: New insight into subduction dynamics

Mapping P-wave anisotropy of the Honshu arc from Japan Trench to the back-arc

P wave azimuthal and radial anisotropy of the Hokkaido subduction zone

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