Electrical conductivity imaging of the Philippine Sea upper mantle using seafloor magnetotelluric data

Baba, Kiyoshi; Utada, Hisashi; Goto, Tada-nori; Kasaya, Takafumi; Shimizu, Hisayoshi; Tada, Norio

doi:10.1016/j.pepi.2010.09.010

Cited by 101 publications

(123 citation statements)

References 43 publications

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“…The same conclusions can be made when comparing the results obtained in models (b) and (d). The field pattern obtained in model (e) (the original model derived by Baba et al (2010) for the Philippine Sea) is similar to those obtained in models (a) and (c), but amplitudes appear to be slightly lower. Similarly, the pattern obtained in model (f) (the original model derived by Baba et al (2010) for the North Pacific) is slightly less pronounced than the patterns obtained in models (b) and (d), and amplitudes are slightly lower.…”

Section: Snapshots Of the Global Pattern Of The Electric Fieldsupporting

confidence: 74%

“…The field pattern obtained in model (e) (the original model derived by Baba et al (2010) for the Philippine Sea) is similar to those obtained in models (a) and (c), but amplitudes appear to be slightly lower. Similarly, the pattern obtained in model (f) (the original model derived by Baba et al (2010) for the North Pacific) is slightly less pronounced than the patterns obtained in models (b) and (d), and amplitudes are slightly lower. We attribute this difference to the increase in conductivity at shallow depths in the models derived by Baba et al (2010) (cf.…”

Section: Snapshots Of the Global Pattern Of The Electric Fieldsupporting

confidence: 74%

“…Similarly, the pattern obtained in model (f) (the original model derived by Baba et al (2010) for the North Pacific) is slightly less pronounced than the patterns obtained in models (b) and (d), and amplitudes are slightly lower. We attribute this difference to the increase in conductivity at shallow depths in the models derived by Baba et al (2010) (cf. Fig.…”

Section: Snapshots Of the Global Pattern Of The Electric Fieldmentioning

confidence: 62%

“…Alternative 1-D sections are based on the study by Baba et al (2010). The authors derived models of the 1-D conductivity structure beneath the Philippine Sea and the North Pacific using sea floor magnetotelluric data, which are more sensitive to structures in the upper mantle than satellite data.…”

Section: Conductivity Modelmentioning

confidence: 99%

“…The authors derived models of the 1-D conductivity structure beneath the Philippine Sea and the North Pacific using sea floor magnetotelluric data, which are more sensitive to structures in the upper mantle than satellite data. Additional computations were performed with 1-D sections based on the results by Baba et al (2010), but using a uniform resistivity for the lithosphere (constituting the upper 100 km). These additional models allow to investigate the importance of the shallow 1-D structure by comparison with the results obtained in the original structures derived by Baba et al (2010) and the importance of the deep 1-D Here, R stands for depth-integrated resistivity (transversal resistance) of the upper 100 km, representing the lithosphere.…”

Section: Conductivity Modelmentioning

confidence: 99%

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Towards quantitative assessment of the hazard from space weather. Global 3-D modellings of the electric field induced by a realistic geomagnetic storm

Püthe

Kuvshinov

2013

Earth Planet Sp

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In order to estimate the hazard to technological systems due to geomagnetically induced currents (GIC), it is crucial to understand the response of the geoelectric field to a geomagnetic disturbance and to provide quantitative estimates of this field. Most previous studies on GIC and the geoelectric field generated during a geomagnetic storm assume a 1-D conductivity structure of Earth. This assumption however is invalid in coastal regions, where the lateral conductivity contrast is large. In this paper, we investigate the global spatio-temporal pattern of the surface geoelectric field induced by a typical major geomagnetic storm in a conductivity model of Earth with realistic laterally-heterogeneous oceans and continents. Exploiting this model makes the problem fully 3-D. Data from worldwide distributed magnetic observatories are used to construct a realistic model of the magnetospheric source. The results of our numerical studies show large amplification of the geoelectric field in many coastal regions. Peak amplitudes obtained with 3-D modelling exceed the amplitudes obtained in a 1-D model by at least a factor 2, even if the latter makes use of the local vertical conductivity structure. Lithosphere resistivity is a critical parameter, which governs both amplitude and penetration width of the anomalous electric field inland.

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Section: Snapshots Of the Global Pattern Of The Electric Fieldsupporting

confidence: 74%

Section: Snapshots Of the Global Pattern Of The Electric Fieldsupporting

confidence: 74%

Section: Snapshots Of the Global Pattern Of The Electric Fieldmentioning

confidence: 62%

Section: Conductivity Modelmentioning

confidence: 99%

Section: Conductivity Modelmentioning

confidence: 99%

See 3 more Smart Citations

Towards quantitative assessment of the hazard from space weather. Global 3-D modellings of the electric field induced by a realistic geomagnetic storm

Püthe

Kuvshinov

2013

Earth Planet Sp

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Is the electrical conductivity of the northwestern Pacific upper mantle normal?

Baba

Tada

Zhang

et al. 2013

Geochem Geophys Geosyst

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[1] The Normal Oceanic Mantle project, based on ocean bottom geophysical observations, has been underway since 2010 to investigate the physical state of the oceanic lithosphere and asthenosphere. We have conducted electromagnetic surveys on old (130 Ma) seafloor in the northwestern Pacific region, where no active tectonic processes have been identified, in order to image the electrical conductivity structure beneath the region. So far, data have been collected at four sites through a pilot survey conducted from June 2010 to August 2012. A one-dimensional electrical conductivity model was obtained by preliminary analysis of the data by using the magnetotelluric method. The model shows that the resistive (<0.01 S m 21) lithospheric mantle is as thick as 80 km, and that the asthenospheric mantle below has a conductivity of 0.03 S m 21. The resistive layer is slightly thicker than that beneath the Philippine Sea but significantly thinner than that beneath the area off the Bonin Trench in the Pacific Ocean. There is a greater difference in age between the survey area and the Philippine Sea (0-60 Ma) than between the survey area and the area off the Bonin Trench (140)(141)(142)(143)(144)(145)(146)(147)(148)(149)(150)(151)(152)(153)(154)(155). This comparison suggests that the relation between age and lithospheric thickness is not as simple as that predicted by the concept of lithospheric cooling. It also suggests that the lithosphere beneath the area off the Bonin Trench in the Pacific Ocean is abnormally thick if the mantle beneath the survey area in this study is ''normal,'' as expected from the plate cooling model.

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Three‐dimensional simulation of the electromagnetic fields induced by the 2011 Tohoku tsunami

et al. 2014

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The motion of seawater induces electromotive force of significant intensity due to Faraday's law, and the resulting electromagnetic (EM) field can be recorded by instruments installed on land or on the ocean bottom. However, few studies have successfully made a quantitative interpretation to obtain geophysical information from observations of tsunami-induced EM signals by an exact and accurate application of Maxwell equations. We built a scheme for three-dimensional numerical simulation to calculate EM fields due to ocean tidal flow and tested the system's accuracy by using the source currents in the ocean as expected from a Tohoku tsunami simulation. Here we show examples of a comparison of data from one land observatory in the Tohoku district, one island observatory in the Izu-Bonin arc, and one seafloor station in the northwest Pacific Ocean. The water motion that generates source current in the sea consists of both the primary poloidal and toroidal magnetic modes. Our numerical simulation shows that the field of the primary toroidal magnetic mode can be effective for seafloor observations but only when the seafloor is highly conductive. We examined how the conductivity of the shallower part of the seabed, composed of sediments, can be constrained by the tsunamiinduced EM field observations, which is difficult in case of using ordinary seafloor magnetotelluric signals. We also defined the motional impedance just as the case of ordinary magnetotellurics and showed that both modeled and observed impedances approximately indicate the phase velocity of the long wave as predicted by a simple theory.

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Electrical conductivity imaging of the Philippine Sea upper mantle using seafloor magnetotelluric data

Cited by 101 publications

References 43 publications

Towards quantitative assessment of the hazard from space weather. Global 3-D modellings of the electric field induced by a realistic geomagnetic storm

Towards quantitative assessment of the hazard from space weather. Global 3-D modellings of the electric field induced by a realistic geomagnetic storm

Is the electrical conductivity of the northwestern Pacific upper mantle normal?

Three‐dimensional simulation of the electromagnetic fields induced by the 2011 Tohoku tsunami

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