P-wave anisotropic tomography beneath Northeast Japan

Wang, Jian; Zhao, Dapeng

doi:10.1016/j.pepi.2008.07.042

Cited by 128 publications

(222 citation statements)

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“…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%

“…The trenchnormal orientation in the back-arc side might originate from the orientation of olivine by mantle wedge corner flow, associated with slab subduction (Hall et al 2000). The trench parallel orientation in the forearc mantle can be explained by the preferred orientation of olivine under wet conditions (Katayama et al 2004), although Wang & Zhao (2008) suggested that the trench-parallel anisotropy beneath the volcanic-front area in the mantle wedge results from the complex 3D flow in the Yoshida et al 1999bYoshida et al , 2005. The size of the circle is correlated to the range of the value in K 60 and plotted on the location of each Quaternary volcano.…”

Section: Along-arc Mantle Heterogeneitymentioning

confidence: 99%

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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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Section: Along-arc Mantle Heterogeneitymentioning

confidence: 99%

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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“…Several researchers have tried to determine P-wave anisotropic tomography in the Japan and New Zealand subduction zones, and the results show that complex anisotropic anomalies exist in wide areas of the crust, mantle wedge and the subducting Pacific slab (e.g., Hirahara and Ishikawa, 1984;Eberhart-Phillips and Henderson, 2004;Ishise and Oda, 2005;Wang and Zhao, 2008, 2009, 2010Cheng et al, 2011). Huang et al (2011a) used a large number of arrivaltime data from local earthquakes in the crust and the subducting Pacific slab to determine a detailed P-wave anisotropic tomography of the NE Japan arc from the Japan Trench to the Japan Sea (Figs.…”

Section: Seismic Anisotropy Tomographymentioning

confidence: 99%

Tomography and Dynamics of Western-Pacific Subduction Zones

Zhao¹

2012

Monogr. Environ. Earth Planets

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We review the significant recent results of multiscale seismic tomography of the Western-Pacific subduction zones and discuss their implications for seismotectonics, magmatism, and subduction dynamics, with an emphasis on the Japan Islands. Many important new findings are obtained due to technical advances in tomography, such as the handling of complex-shaped velocity discontinuities, the use of various later phases, the joint inversion of local and teleseismic data, tomographic imaging outside a seismic network, and P-wave anisotropy tomography. Prominent low-velocity (low-V ) and high-attenuation (low-Q) zones are revealed in the crust and uppermost mantle beneath active arc and back-arc volcanoes and they extend to the deeper portion of the mantle wedge, indicating that the low-V /low-Q zones form the sources of arc magmatism and volcanism, and the arc magmatic system is related to deep processes such as convective circulation in the mantle wedge and dehydration reactions in the subducting slab. Seismic anisotropy seems to exist in all portions of the Northeast Japan subduction zone, including the upper and lower crust, the mantle wedge and the subducting Pacific slab. Multilayer anisotropies with different orientations may have caused the apparently weak shear-wave splitting observed so far, whereas recent results show a greater effect of crustal anisotropy than previously thought. Deep subduction of the Philippine Sea slab and deep dehydration of the Pacific slab are revealed beneath Southwest Japan. Significant structural heterogeneities are imaged in the source areas of large earthquakes in the crust, subducting slab and interplate megathrust zone, which may reflect fluids and/or magma originating from slab dehydration that affected the rupture nucleation of large earthquakes. These results suggest that large earthquakes do not strike anywhere, but in only anomalous areas that may be detected with geophysical methods. The occurrence of deep earthquakes under the Japan Sea and the East Asia margin may be related to a metastable olivine wedge in the subducting Pacific slab. The Pacific slab becomes stagnant in the mantle transition zone under East Asia, and a big mantle wedge (BMW) has formed above the stagnant slab. Convective circulations and fluid and magmatic processes in the BMW may have caused intraplate volcanism (e.g., Changbai and Wudalianchi), reactivation of the North China craton, large earthquakes, and other active tectonics in East Asia. Deep subduction and dehydration of continental plates (such as the Eurasian plate, Indian plate and Burma microplate) are also found, which have caused intraplate magmatism (e.g., Tengchong) and geothermal anomalies above the subducted continental plates. Under Kamchatka, the subducting Pacific slab shortens toward the north and terminates near the Aleutian-Kamchatka junction. The slab loss was induced by friction with the surrounding asthenosphere, as the Pacific plate rotated clockwise 30 Ma ago, and then it was enlarged by the slab-edge pinch-off b...

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“…Thus, the partial derivatives of the travel time with respect to the velocity and radial anisotropy are expressed as: (2.33) Similar to the P-wave tomography for azimuthal anisotropy (Wang and Zhao 2008), V k and M k 1 at a point are calculated using linear interpolation of the parameters…”

Section: P-wave Radial Anisotropy Tomographymentioning

confidence: 99%

Methodology of Seismic Tomography

Zhao

2015

Multiscale Seismic Tomography

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In this chapter, we introduce the tomographic methods which are widely used to study three-dimensional (3-D) seismic velocity, attenuation and anisotropy structures of the Earth's interior. The fundamental mathematical equations of these methods are presented for a better understanding of the principles of seismic tomography.Keywords Seismic tomography · Model parameterization · Ray tracing · Inversion · Resolution · Damping parameter From seismological observations, such as P-and S-wave arrival times, amplitudes, and waveforms, basically three kinds of physical parameters can be determined to characterize the seismological structure of the Earth's interior. These parameters are seismic velocity, attenuation, and anisotropy. Applying tomographic methods to the seismological data, we can estimate the three-dimensional (3-D) distribution of these parameters, i.e., seismic velocity tomography, attenuation tomography, and anisotropy tomography. In this chapter, we introduce the general approaches to conduct the three kinds of tomographic inversions.In general, a study of seismic tomography includes the following operations: (1) Modeling the Earth's interior structure, i.e., model parameterization; (2) Forward modeling, such as ray tracing in travel-time tomography, earthquake relocation, and the construction of observation equations; (3) Inversion, i.e., solving the large system of observation equations; and (4) Resolution and error analysis, i.e., evaluating the resolution and uncertainty of the obtained tomographic image. Seismic Velocity TomographySince the advent of seismology, P-and S-wave velocities (Vp, Vs) have been the primary physical parameters to characterize the Earth's structure because they are determined mainly from P-and S-wave arrival-time data which can be measured in high quality and great quantity by the routine processing of seismic networks deployed in many regions. Hence, earthquake arrival times have been the most

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P-wave anisotropic tomography beneath Northeast Japan

Cited by 128 publications

References 73 publications

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

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

Tomography and Dynamics of Western-Pacific Subduction Zones

Methodology of Seismic Tomography

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