Upper mantle anisotropy beneath central and southwest Japan: An insight into subduction-induced mantle flow

Salah, Mohamеd K.; Seno, Tetsuzo; Iidaka, Takashi

doi:10.1016/j.jog.2008.04.002

Cited by 17 publications

(17 citation statements)

References 51 publications

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“…Trench-parallel FVDs also appear in the mantle wedge under the volcanic front in Tohoku, but not in Kyushu, suggesting that 3-D flow may exist in the mantle wedge under Tohoku caused by the large subduction rate of the Pacific plate (7-10 cm/year). This FVD pattern of trench-normal in the back-arc and trench-parallel in the fore-arc is very consistent with shear-wave splitting measurements in Tohoku (Okada et al 1995;Nakajima et al 2006;Huang et al 2011b, c) and in Kyushu (e.g., Salah et al 2008;Terada et al 2013). …”

Section: Seismic Anisotropy Tomographysupporting

confidence: 88%

Subduction Zone Tomography

Zhao

2015

Multiscale Seismic Tomography

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In this chapter, we review recent seismic tomography studies of subduction zones and new insights into arc magmatism, seismotectonics and subduction dynamics. Seismic velocity and attenuation tomography clearly reveals subducting slabs as high-velocity and low-attenuation zones, where intermediate-depth and deep earthquakes occur. In the crust and upper-mantle wedge, low-velocity (low-V) and high-attenuation (low-Q) anomalies are revealed beneath arc and back-arc volcanoes, and they extend to a deeper portion of the mantle wedge, indicating that the low-V and low-Q anomalies reflect source zones of arc magmatism and volcanism which are caused by corner flow in the mantle wedge and fluids from slab dehydration. P-wave anisotropy tomography and shear-wave splitting measurements also provide important constraints on mantle flows and dynamics in subduction zones.

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Section: Seismic Anisotropy Tomographysupporting

confidence: 88%

Subduction Zone Tomography

Zhao

2015

Multiscale Seismic Tomography

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“…Recent teleseismic tomography shows that the PHS plate has subducted aseismically down to 460 km depth under the Japan Sea, Tsushima Strait and East China Sea, and a window exists within the aseismic PHS slab . SWS measurements have been made, which revealed the existence of significant anisotropy in SW Japan (e.g., Ando et al, 1983;Kaneshima, 1990;Hiramatsu et al, 1997;Salah et al, 2008;Terada et al, 2013). P-wave tomography for azimuthal anisotropy beneath SW Japan has been investigated by Ishise and Oda (2008) and Zhao (2012, 2013).…”

Section: Southwest Japanmentioning

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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“…A transition from trench-parallel splitting close to the trench to trench-perpendicular further in the backarc has been observed in several regions (e.g., northern Honshu; Nakajima and Hasegawa 2004), but the opposite transition has been observed in a few regions, including Kamchatka . In some wedges, the spatial pattern of fast directions is extremely complicated, such as central Japan (Salah et al 2008;Wirth and Long 2008). As with the sub-slab case, the pattern that would be predicted for a simple corner flow model with A-type olivine fabric-dominantly trenchperpendicular fast directions-is virtually absent from the global database.…”

Section: Subduction Zonesmentioning

confidence: 99%

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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Upper mantle anisotropy beneath central and southwest Japan: An insight into subduction-induced mantle flow

Cited by 17 publications

References 51 publications

Subduction Zone Tomography

Subduction Zone Tomography

Seismic anisotropy tomography: New insight into subduction dynamics

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

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