Three-dimensional P- and S-wave velocity structures beneath Japan

Nakamura, Masaki; Yoshida, Yasuhiro; Zhao, Dapeng; Takayama, Hajime; Obana, Koichiro; Katao, Hiroshi; Kasahara, Junzo; Kanazawa, Toshihiko; Kodaira, Shuichi; Sato, Toshinori; Shiobara, Hajime; Shinohara, Masanao; Shimamura, Hideki; Takahashi, Narumi; Nakanishi, Ayako; Hino, Ryota; Murai, Yoshio; Mochizuki, Kimihiro

doi:10.1016/j.pepi.2008.04.017

Cited by 25 publications

(27 citation statements)

References 42 publications

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“…The anisotropic region found in their study was consistent with a low-velocity region obtained from seismic tomography (Hirahara et al 1989;Sekiguchi 1991); thus, they concluded that the cause of the anisotropy was related to the heterogeneous structures created by fluid-filled cracks. Nakamura et al (2008) found velocity perturbations that suggested a low-Vp region at depths of ~100-150 km beneath the eastern part of our study area; however, there was no corresponding lowVs region at the same depths. If the cause of the anisotropy is truly fluid-filled cracks, then the area should be characterized by low-Vs and low-Q regions (e.g., Iidaka and Obara 1995;Hiramatsu et al 1998).…”

Section: Heterogeneous Mantle Anisotropy and Its Origincontrasting

confidence: 49%

Heterogeneous mantle anisotropy and fluid upwelling: implication for generation of the 1891 Nobi earthquake

Iidaka

Hiramatsu

2016

Earth Planets Space

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The 1891 Nobi earthquake was the largest historic intraplate earthquake in Japan. The rupture origin corresponds to a zone of high strain rate inferred from geodetic data. To understand the geologic setting of this event, we deployed temporary seismic stations in the area. Shear-wave splitting analysis was performed using data from temporary and permanent seismic stations, revealing significant lateral variations in polarization directions. Polarization directions of NE-SW, ESE-WNW, and ENE-WSW were observed in the northeastern, central, and southwestern parts of the study area, respectively. The NE-SW-and ENE-WSW-aligned polarizations are consistent with the subduction directions of the Philippine Sea plate and Pacific plate, respectively; thus, shear-wave splitting in the northeastern and southwestern regions of the study area is likely caused by mantle wedge anisotropy, a consequence of mantle flow caused by the subducting oceanic slabs. However, the ESE-WNW orientations observed in the central Chubu Region are inconsistent with the subduction direction of either slab. Regions of low seismic velocity and low resistivity have been reported in the inferred position of the mantle wedge; these heterogeneities are thought to be caused by fluid rising from the dehydrated oceanic slabs. Thus, the ESE-WNW polarization in central Chubu could be a consequence of structural heterogeneities created by fluid to the crust from the mantle. The presence of crustal fluid is closely related to weakening, and the faults responsible for the 1891 Nobi earthquake are located just above the anisotropic region. Because fluids in the crust weaken the surrounding rock, this could explain the occurrence of the 1891 Nobi earthquake.

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Section: Heterogeneous Mantle Anisotropy and Its Origincontrasting

confidence: 49%

Heterogeneous mantle anisotropy and fluid upwelling: implication for generation of the 1891 Nobi earthquake

Iidaka

Hiramatsu

2016

Earth Planets Space

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“…This seismological feature has been found in all subduction zones which have been studied using seismic tomography (e.g., Zhao et al , 2000Ma et al 1996;Nakajima et al 2001;McNamara and Pasyanos 2002;Nakamura et al 2003Nakamura et al , 2008Wagner et al 2005Wagner et al , 2010Zhao 2005, 2006a, b;Katsumata et al 2006;Matsubara et al 2008;Wiens et al 2008;van Stiphout et al 2009;Schmandt and Humphreys 2010;Bianchi et al 2013;Liu et al 2013a, b, and many other references mentioned in this and the following sections). 3.2, 3.3, 3.4, 3.5, 3.7, 3.8, 3.9, 3.10, 3.11, 3.12 and 3.13).…”

Section: Mantle Wedge and Arc Magmatismmentioning

confidence: 72%

Multiscale Seismic Tomography

Zhao

2015

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“…The systematic absence of healing in intact tectonites can be attributed to the presence of interconnected clay layers that "saturate" the growth of real contact area and at the same time inhibit compaction and healing via solution transfer between soluble calcite grains (e.g. Niemeijer and Spiers, 2006;Tesei et al, 2012).…”

Section: Frictional Stability Analysismentioning

confidence: 99%

“…Prescott et al, 1981;Perfettini et al, 2010;Jolivet et al, 2013;Thomas, 2014) and characterized by heterogeneous materials and variable states of fluid pressure, inferred from seismic velocity and earthquake distributions (e.g. Nakamura et al, 2008;Saffer and Tobin, 2011;Zhao et al, 2011;Valoroso et al, 2014).…”

Section: Introductionmentioning

confidence: 99%