Shear‐wave splitting beneath the southwestern Kurile arc and northeastern Japan arc: A new insight into mantle return flow

Nakajima, Jun; Shimizu, J.; Hori, Shuichiro; Hasegawa, Akira

doi:10.1029/2005gl025053

Cited by 94 publications

(102 citation statements)

References 27 publications

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“…The 16°angle is close to the 15°standard deviation angle of each station computed in section 6.1. The near-surface polarization in the western part of Figure 13b correlates well with observations of the shear wave polarization at greater depth [Okada et al, 1995;Nakajima and Hasegawa, 2004;Nakajima et al, 2006], but this agreement does not hold in the regions further east.…”

Section: Shear Wave Splitting and The Direction Of The Plate Motionsupporting

confidence: 74%

Estimating near‐surface shear wave velocities in Japan by applying seismic interferometry to KiK‐net data

2012

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[1] We estimate shear wave velocities in the shallow subsurface throughout Japan by applying seismic interferometry to the data recorded with KiK-net, a strong motion network in Japan. Each KiK-net station has two receivers; one receiver on the surface and the other in a borehole. By using seismic interferometry, we extract the shear wave that propagates between these two receivers. Applying this method to earthquake-recorded data at all KiK-net stations from 2000 to 2010 and measuring the arrival time of these shear waves, we analyze monthly and annual averages of the near-surface shear wave velocity all over Japan. Shear wave velocities estimated by seismic interferometry agree well with the velocities obtained from logging data. The estimated shear wave velocities of each year are stable. For the Niigata region, we observe a velocity reduction caused by major earthquakes. For stations on soft rock, the measured shear wave velocity varies with the seasons, and we show negative correlation between the shear wave velocities and precipitation. We also analyze shear wave splitting by rotating the horizontal components of the surface sensors and borehole sensors and measuring the dependence on the shear wave polarization. This allows us to estimate the polarization with the fast shear wave velocity throughout Japan. For the data recorded at the stations built on hard rock sites, the fast shear wave polarization directions correlate with the direction of the plate motion.Citation: Nakata, N., and R. Snieder (2012), Estimating near-surface shear wave velocities in Japan by applying seismic interferometry to KiK-net data,

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Section: Shear Wave Splitting and The Direction Of The Plate Motionsupporting

confidence: 74%

Estimating near‐surface shear wave velocities in Japan by applying seismic interferometry to KiK‐net data

2012

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“…In NE Japan, a clear pattern on the polarization direction of shear-wave splitting was found (Nakajima et al, 2006). Trench-parallel and trench-normal polarization directions were found at the fore-arc side and back-arc side of the volcanic front, respectively.…”

Section: Resultsmentioning

confidence: 88%

Shear-wave splitting analysis of the upper mantle at the Niigata-Kobe Tectonic Zone with the data of the Joint Seismic Observations at NKTZ

Iidaka

Hiramatsu

2009

Earth Planet Sp

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We conducted seismic observations with a spatially high density seismic network at the Niigata-Kobe Tectonic Zone, central Japan. The seismic network was used for the analysis of shear-wave splitting. Large lateral variations were found in the polarization direction data: the northern part of the research area yields polarization directions of NW-SE (Region A), the central part of the research area with the polarization direction of NNE-SSW (Region B), the eastern part of the research area with the polarization direction of NE-SW (Region C), and the southern part of the research area with the polarization direction of E-W (Region D). The polarization directions in Regions B and C could be explained by the preferred orientation of olivine caused by the flow of the subducting Philippine Sea plate. However, the cause of anisotropic region which was related to the heterogeneous structure was also plausible. The polarization direction in Region A might be related to the flow caused by both of the subducting Philippine Sea and Pacific slabs. The polarization direction at the Region D could not be produced by the flow in the wedge and might be related to an anisotropic region beneath the slab. The lateral variation of the polarization direction does not support a model that the NKTZ is a collision region.

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“…These reflect the changes in allocation of the arc-trench system before and after the opening of the Japan Sea; the latter was NE-SW (oblique to the present NE Japan arc) before the opening, and NNE-SSW (parallel to the present NE Japan arc) after the opening until the present (Otufuji et al 1985;Ohki et al 1993;Yoshida et al 1999b). The present-day mantle structure, including the low velocity and mantle anisotropy structures Nakajima et al 2006b), is principally parallel to the present arc-trench system, although there are some mantle heterogeneities in the areas of SW Honshu and NE Honshu bordered by the TTL. Therefore, it is likely that the along-arc spatial variation of the Quaternary lava chemistry is mainly affected by the overlying lithosphere, and the most plausible candidate for affecting this appears to be the lower crustal melts, which can contribute to both the origin of the basement granitoids and to the Quaternary lavas.…”

Section: Role Of the Heterogeneous Lower Crustmentioning

confidence: 99%

“…Shearwave splitting analyses reveal that the low-V and low-Q zones in the mantle wedge show strong seismic anisotropies (Okada et al 1995;, Nakajima et al 2006b). Anisotropic bodies are revealed in the crust, mantle wedge and the subducting Pacific slab (Hall et al 2000;Nakajima et al 2006b;Wang & Zhao 2008;Huang et al 2010). have clearly shown that the azimuth in the forearc region is trench-parallel, whereas in the back-arc region the azimuth is trench-normal (Fig.…”

Section: Along-arc Mantle Heterogeneitymentioning

confidence: 99%

Evolution of late Cenozoic magmatism and the crust–mantle structure in the NE Japan Arc

Yoshida

Kimura

Yamada

et al. 2013

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107

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Abstract:We review the evolution of late Cenozoic magmatism in the NE Japan arc, and examine the relationship between the magmatism and the crust-mantle structure. Recent studies reveal secular changes in the mode of magmatic activity, the magma plumbing system, erupted volumes and magmatic composition associated with the evolution of crust-mantle structures related to the tectonic evolution of the arc. The evolution of Cenozoic magmatism in the arc can be divided into three periods: the continental margin (66-21 Ma), the back-arc basin (21-13.5 Ma) and the island-arc period (13.5-0 Ma). Magmatic evolution in the back-arc basin and the island-arc periods appears to be related to the 2D to 3D change in the convection pattern of the mantle wedge related to the asthenosphere upwelling and subsequent cooling of the mantle. Geodynamic changes in the mantle caused back-arc basin basalt eruptions during the back-arc basin opening (basalt phase) followed by crustal heating and re-melting, which generated many felsic plutons and calderas (rhyolite/granite phase) in the early stage of the island-arc period. This was followed by crustal cooling and strong compression, which ensured vent connections and mixing between deeper mafic and shallower felsic magmas, erupting large volumes of Quaternary andesites (andesite phase).Gold Open Access: This article is published under the terms of the CC-BY 3.0 license.The NE Japan arc is a typical island arc associated with a cold subduction zone. It is one of the most well-known island arcs on Earth and provides a useful model for our understanding of how subduction zones produce magmas, including andesites. The NE Japan arc is related to the westward

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Shear‐wave splitting beneath the southwestern Kurile arc and northeastern Japan arc: A new insight into mantle return flow

Cited by 94 publications

References 27 publications

Estimating near‐surface shear wave velocities in Japan by applying seismic interferometry to KiK‐net data

Estimating near‐surface shear wave velocities in Japan by applying seismic interferometry to KiK‐net data

Shear-wave splitting analysis of the upper mantle at the Niigata-Kobe Tectonic Zone with the data of the Joint Seismic Observations at NKTZ

Evolution of late Cenozoic magmatism and the crust–mantle structure in the NE Japan Arc

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