Resistivity imaging across the source region of the 2004 Mid-Niigata Prefecture earthquake (M6.8), central Japan

Uyeshima, Makoto; Ogawa, Yasuo; Honkura, Yoshimori; Koyama, Shigeru; Ujihara, Naoto; Mogi, Toru; Yamaya, Yusuke; Harada, Makoto; Yamaguchi, Satoru; Shiozaki, Ichiro; Noguchi, Tatsuya; Kuwaba, Yoshihiro; Tanaka, Yoshikazu; Mochido, Yuji; Manabe, Noriko; Nishihara, Masanori; Saka, Mamoru; Serizawa, Masato

doi:10.1186/bf03351831

Cited by 43 publications

(20 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This study shows that the seismogenic zones correspond approximately to resistive zones lying adjacent to conductive zones, or to the conductive-resistive transition zone. These results are consistent with previous magnetotelluric studies conducted across the epicenters of large (>M 6) inland earthquakes (Mitsuhata et al 2001;Ogawa et al 2001;Tank et al 2003Tank et al , 2005Kasaya and Oshiman 2004;Ichihara et al 2008Ichihara et al , 2014Yoshimura et al 2008;Kaya et al 2009;Umeda et al 2011Umeda et al , 2014Chandrasekhar et al 2012) with the exception that aftershocks occur in a thick sedimentary layer (Uyeshima et al 2005). Note here that the dense magnetotelluric observations occasionally image localized subvertical conductors beneath the active faults (e.g., Unsworth et al 1997;Wannamaker et al 2002;Becken et al 2008;Ikeda et al 2013;Sass et al 2014).…”

Section: Discussionsupporting

confidence: 82%

Seismicity controlled by resistivity structure: the 2016 Kumamoto earthquakes, Kyushu Island, Japan

Aizawa

Asaue

Koike

et al. 2017

Earth Planets Space

Self Cite

View full text Add to dashboard Cite

The M JMA 7.3 Kumamoto earthquake that occurred at 1:25 JST on April 16, 2016, not only triggered aftershocks in the vicinity of the epicenter, but also triggered earthquakes that were 50-100 km away from the epicenter of the main shock. The active seismicity can be divided into three regions: (1) the vicinity of the main faults, (2) the northern region of Aso volcano (50 km northeast of the mainshock epicenter), and (3) the regions around three volcanoes, Yufu, Tsurumi, and Garan (100 km northeast of the mainshock epicenter). Notably, the zones between these regions are distinctively seismically inactive. The electric resistivity structure estimated from one-dimensional analysis of the 247 broadband (0.005-3000 s) magnetotelluric and telluric observation sites clearly shows that the earthquakes occurred in resistive regions adjacent to conductive zones or resistive-conductive transition zones. In contrast, seismicity is quite low in electrically conductive zones, which are interpreted as regions of connected fluids. We suggest that the series of the earthquakes was induced by a local accumulated stress and/or fluid supply from conductive zones. Because the relationship between the earthquakes and the resistivity structure is consistent with previous studies, seismic hazard assessment generally can be improved by taking into account the resistivity structure. Following on from the 2016 Kumamoto earthquake series, we suggest that there are two zones that have a relatively high potential of earthquake generation along the western extension of the MTL.

show abstract

Section: Discussionsupporting

confidence: 82%

Seismicity controlled by resistivity structure: the 2016 Kumamoto earthquakes, Kyushu Island, Japan

Aizawa

Asaue

Koike

et al. 2017

Earth Planets Space

Self Cite

View full text Add to dashboard Cite

show abstract

“…2) (e.g., Xia et al, 2008b;Kato et al, 2010). An anomaly with low-V and high-PR in the lower crust and uppermost mantle was revealed under the Niigata source areas, which also exhibits high conductivity and a high He 3 /He 4 ratio (Ogawa and Honkura, 2004;Uyeshima et al, 2005;Horiguchi et al, 2010), indicating the existence of fluids under the EMJS rising from the upper mantle as a result of slab dehydration and corner flow in the mantle wedge. Some large thrust faults during large earthquakes may cut through the whole crust (Satake, 1986;Tanioka et al, 1995).…”

Section: Back-arc: Eastern Margin Of Japan Seamentioning

confidence: 99%

Tomography and Dynamics of Western-Pacific Subduction Zones

Zhao¹

2012

Monogr. Environ. Earth Planets

View full text Add to dashboard Cite

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...

show abstract

“…Unsworth et al, 2000;Ogawa and Honkura, 2004;Tank et al, 2005) but also intraplate earthquakes (e.g. Mitsuhata et al, 2001;Ogawa et al, 2001;Uyeshima et al, 2005). In view of the sensitivity of resistivity to the ex- istence of fluids, joint interpretations of electric properties with other geophysical information will extend our knowledge of the field conditions around source regions of intraplate earthquakes.…”

Section: Introductionmentioning

confidence: 99%

Magnetotelluric observations around the focal region of the 2007 Noto Hanto Earthquake (Mj 6.9), Central Japan

et al. 2008

Self Cite

View full text Add to dashboard Cite

On 25 March 2007, a damaging earthquake (M j 6.9) occurred near the west coast of the Noto Peninsula, Central Japan. A wideband magnetotelluric (MT) survey was carried out in the onshore area of the source region immediately after the mainshock, with the aim of imaging the heterogeneity of the crustal resistivity structure. The final observation network had consisted of 26 sites. As a preparatory step for imaging threedimensional features of the resistivity around the focal region, we constructed two-dimensional resistivity models along five profiles using only the TM mode responses, in order to reduce three-dimensional effects. Four profiles are perpendicular to the fault strike, and a fifth profile is parallel to the strike through the mainshock epicenter. Significant characteristics of the resistivity models are: (1) beneath the mainshock hypocenter, there is a conductive body which spreads to the eastern edge of the active aftershock region; (2) a resistive zone is located in the gap of the aftershock distribution between the mainshock hypocenter and the largest eastern aftershock; (3) one of the largest aftershock occurred at the boundary of the resistive zone described above. These results suggest that the deep conductors represent fluid-filled zones and that the lateral heterogeneity could have controlled the slip distribution on the fault plane.

show abstract

Resistivity imaging across the source region of the 2004 Mid-Niigata Prefecture earthquake (M6.8), central Japan

Cited by 43 publications

References 22 publications

Seismicity controlled by resistivity structure: the 2016 Kumamoto earthquakes, Kyushu Island, Japan

Seismicity controlled by resistivity structure: the 2016 Kumamoto earthquakes, Kyushu Island, Japan

Tomography and Dynamics of Western-Pacific Subduction Zones

Magnetotelluric observations around the focal region of the 2007 Noto Hanto Earthquake (Mj 6.9), Central Japan

Contact Info

Product

Resources

About