Telluric Current

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M. Cao - One of the best experts on this subject based on the ideXlab platform.

  • Ionospheric influence on the seismo-Telluric Current related toelectromagnetic signals observed before the Wenchuan M S 8.0 earthquake
    Solid Earth, 2016
    Co-Authors: H. Tan, M. Cao
    Abstract:

    Abstract. A three-layer (Earth–air–ionosphere) physical model, as well as a two-layer (Earth–air) model, is employed in this paper to investigate the ionospheric effect on the wave fields for a finite length dipole Current source co-located at a hypocenter depth and along the main fault of an earthquake when the distance between the epicenter and an observing station is up to 1000 km or even more. The results show that all electrical fields are free of ionospheric effects for different frequencies in a relative short range, e.g.,  ∼  300 km for f =  1 Hz, implying the ionospheric influence on electromagnetic fields can be neglected within this range, which becomes smaller as the frequency increases. However, the ionosphere can give a constructive interference to the waves passing through and make them decay slowly when an observation is out of this range; moreover, the ionospheric effect can be up to 1–2 orders of magnitude of the electrical fields. For a ground-based observable 1.3 mV m−1 electric signal at f =  1 Hz 1440 km away from the Wenchuan MS 8.0 earthquake, the expected seismo-Telluric Current magnitude for the Earth–air–ionosphere model is of 5.0  ×  107A, 1 magnitude smaller than the Current value of 3.7  ×  108A obtained by the Earth–air model free of ionospheric effects. This indicates that the ionosphere facilitates the electromagnetic wave propagation, as if the detectability of the system were improved effectively and it is easier to record a signal even for stations located at distances beyond their detectability thresholds. Furthermore, the radiating patterns of the electrical field components |Ex| and |Ey| are complementary to each other, although any two-dimensional (2-D) power distribution of these components shows strong power areas as well as weak ones, which is advantageous to register a signal if the observing system is designed to measure both of them instead of only one.

  • Ionospheric influence on the seismo-Telluric Current related to electromagnetic signals observed before the Wenchuan <i>M</i><sub>S</sub> = 8.0 earthquake
    2016
    Co-Authors: H. Tan, M. Cao
    Abstract:

    Abstract. A three-layer (Earth-air-ionosphere) physical model, as well as a two-layer (Earth-air) model, is employed in this paper to investigate the ionospheric effect on the wave fields for a finite length dipole Current source co-located with the main fault of an earthquake when the transmitter-receiver distance is up to one thousand kilometers or even more. The results show that all electrical fields are free of the ionospheric effect for different frequencies in a relative short range, e.g., ~ 300 km for f = 1 Hz, implying the ionospheric influence on electromagnetic fields can be neglected within this range that becomes smaller as the frequency increases. However, the ionosphere can give a constructive interference to the waves passed through and make them decay slowly when an observation is out of this range and the ionosperic effect can be up to 1–2 magnitudes of the electrical fields. For an observed 1.3 mV/m signal at 1,440 km away for the Wenchuan MS = 8.0 earthquake, the expected seismo-Telluric Current magnitude for the Earth-air-ionosphere model is of 5.0 × 104 kA , which is of one magnitude smaller than the Current value of 3.7 × 105 kA obtained by the Earth-air model free of ionospheric effect. This indicates that the ionosphere facilitates the electromagnetic wave propagation, as if the detectability of the system is improved effectively and it is easier to record a signal even for stations located at distances beyond their detectability threshold.

  • Ionospheric influence on the seismo-Telluric Current related to electromagnetic signals observed before the Wenchuan MS 8.0 earthquake
    Copernicus Publications, 2016
    Co-Authors: H. Tan, M. Cao
    Abstract:

    A three-layer (Earth–air–ionosphere) physical model, as well as a two-layer (Earth–air) model, is employed in this paper to investigate the ionospheric effect on the wave fields for a finite length dipole Current source co-located at a hypocenter depth and along the main fault of an earthquake when the distance between the epicenter and an observing station is up to 1000 km or even more. The results show that all electrical fields are free of ionospheric effects for different frequencies in a relative short range, e.g.,  ∼  300 km for f =  1 Hz, implying the ionospheric influence on electromagnetic fields can be neglected within this range, which becomes smaller as the frequency increases. However, the ionosphere can give a constructive interference to the waves passing through and make them decay slowly when an observation is out of this range; moreover, the ionospheric effect can be up to 1–2 orders of magnitude of the electrical fields. For a ground-based observable 1.3 mV m−1 electric signal at f =  1 Hz 1440 km away from the Wenchuan MS 8.0 earthquake, the expected seismo-Telluric Current magnitude for the Earth–air–ionosphere model is of 5.0  ×  107A, 1 magnitude smaller than the Current value of 3.7  ×  108A obtained by the Earth–air model free of ionospheric effects. This indicates that the ionosphere facilitates the electromagnetic wave propagation, as if the detectability of the system were improved effectively and it is easier to record a signal even for stations located at distances beyond their detectability thresholds. Furthermore, the radiating patterns of the electrical field components |Ex| and |Ey| are complementary to each other, although any two-dimensional (2-D) power distribution of these components shows strong power areas as well as weak ones, which is advantageous to register a signal if the observing system is designed to measure both of them instead of only one

Gaochuan Liu - One of the best experts on this subject based on the ideXlab platform.

H. Tan - One of the best experts on this subject based on the ideXlab platform.

  • Ionospheric influence on the seismo-Telluric Current related toelectromagnetic signals observed before the Wenchuan M S 8.0 earthquake
    Solid Earth, 2016
    Co-Authors: H. Tan, M. Cao
    Abstract:

    Abstract. A three-layer (Earth–air–ionosphere) physical model, as well as a two-layer (Earth–air) model, is employed in this paper to investigate the ionospheric effect on the wave fields for a finite length dipole Current source co-located at a hypocenter depth and along the main fault of an earthquake when the distance between the epicenter and an observing station is up to 1000 km or even more. The results show that all electrical fields are free of ionospheric effects for different frequencies in a relative short range, e.g.,  ∼  300 km for f =  1 Hz, implying the ionospheric influence on electromagnetic fields can be neglected within this range, which becomes smaller as the frequency increases. However, the ionosphere can give a constructive interference to the waves passing through and make them decay slowly when an observation is out of this range; moreover, the ionospheric effect can be up to 1–2 orders of magnitude of the electrical fields. For a ground-based observable 1.3 mV m−1 electric signal at f =  1 Hz 1440 km away from the Wenchuan MS 8.0 earthquake, the expected seismo-Telluric Current magnitude for the Earth–air–ionosphere model is of 5.0  ×  107A, 1 magnitude smaller than the Current value of 3.7  ×  108A obtained by the Earth–air model free of ionospheric effects. This indicates that the ionosphere facilitates the electromagnetic wave propagation, as if the detectability of the system were improved effectively and it is easier to record a signal even for stations located at distances beyond their detectability thresholds. Furthermore, the radiating patterns of the electrical field components |Ex| and |Ey| are complementary to each other, although any two-dimensional (2-D) power distribution of these components shows strong power areas as well as weak ones, which is advantageous to register a signal if the observing system is designed to measure both of them instead of only one.

  • Ionospheric influence on the seismo-Telluric Current related to electromagnetic signals observed before the Wenchuan <i>M</i><sub>S</sub> = 8.0 earthquake
    2016
    Co-Authors: H. Tan, M. Cao
    Abstract:

    Abstract. A three-layer (Earth-air-ionosphere) physical model, as well as a two-layer (Earth-air) model, is employed in this paper to investigate the ionospheric effect on the wave fields for a finite length dipole Current source co-located with the main fault of an earthquake when the transmitter-receiver distance is up to one thousand kilometers or even more. The results show that all electrical fields are free of the ionospheric effect for different frequencies in a relative short range, e.g., ~ 300 km for f = 1 Hz, implying the ionospheric influence on electromagnetic fields can be neglected within this range that becomes smaller as the frequency increases. However, the ionosphere can give a constructive interference to the waves passed through and make them decay slowly when an observation is out of this range and the ionosperic effect can be up to 1–2 magnitudes of the electrical fields. For an observed 1.3 mV/m signal at 1,440 km away for the Wenchuan MS = 8.0 earthquake, the expected seismo-Telluric Current magnitude for the Earth-air-ionosphere model is of 5.0 × 104 kA , which is of one magnitude smaller than the Current value of 3.7 × 105 kA obtained by the Earth-air model free of ionospheric effect. This indicates that the ionosphere facilitates the electromagnetic wave propagation, as if the detectability of the system is improved effectively and it is easier to record a signal even for stations located at distances beyond their detectability threshold.

  • Ionospheric influence on the seismo-Telluric Current related to electromagnetic signals observed before the Wenchuan MS 8.0 earthquake
    Copernicus Publications, 2016
    Co-Authors: H. Tan, M. Cao
    Abstract:

    A three-layer (Earth–air–ionosphere) physical model, as well as a two-layer (Earth–air) model, is employed in this paper to investigate the ionospheric effect on the wave fields for a finite length dipole Current source co-located at a hypocenter depth and along the main fault of an earthquake when the distance between the epicenter and an observing station is up to 1000 km or even more. The results show that all electrical fields are free of ionospheric effects for different frequencies in a relative short range, e.g.,  ∼  300 km for f =  1 Hz, implying the ionospheric influence on electromagnetic fields can be neglected within this range, which becomes smaller as the frequency increases. However, the ionosphere can give a constructive interference to the waves passing through and make them decay slowly when an observation is out of this range; moreover, the ionospheric effect can be up to 1–2 orders of magnitude of the electrical fields. For a ground-based observable 1.3 mV m−1 electric signal at f =  1 Hz 1440 km away from the Wenchuan MS 8.0 earthquake, the expected seismo-Telluric Current magnitude for the Earth–air–ionosphere model is of 5.0  ×  107A, 1 magnitude smaller than the Current value of 3.7  ×  108A obtained by the Earth–air model free of ionospheric effects. This indicates that the ionosphere facilitates the electromagnetic wave propagation, as if the detectability of the system were improved effectively and it is easier to record a signal even for stations located at distances beyond their detectability thresholds. Furthermore, the radiating patterns of the electrical field components |Ex| and |Ey| are complementary to each other, although any two-dimensional (2-D) power distribution of these components shows strong power areas as well as weak ones, which is advantageous to register a signal if the observing system is designed to measure both of them instead of only one

Xin Zhang - One of the best experts on this subject based on the ideXlab platform.

W. H. Seager - One of the best experts on this subject based on the ideXlab platform.

  • Telluric Currents: A Meeting of Theory and Observation
    CORROSION, 1998
    Co-Authors: David Boteler, W. H. Seager
    Abstract:

    Abstract Pipe-to-soil (P/S) potential variations resulting from Telluric Currents have been observed on pipelines in many locations. However, it has never been clear which parts of a pipeline will experience the worst effects. Two studies were conducted to answer this question. Distributed-source transmission line (DSTL) theory was applied to the problem of modeling geomagnetic induction in pipelines. This theory predicted that the largest P/S potential variations would occur at the ends of the pipeline. The theory also predicted that large P/S potential variations, of opposite sign, should occur on either side of an insulating flange. Independently, an observation program was conducted to determine the change in Telluric Current P/S potential variations and to design counteractive measures along a pipeline in northern Canada. Observations showed that the amplitude of P/S potential fluctuations had maxima at the northern and southern ends of the pipeline. A further set of recordings around an insulating f...

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