Telluric current

From Freepedia

A telluric current (sometimes referred to as magnetotelluric) is a extremely low frequency electrical current that occurs naturally over large underground areas at or near the surface of the Earth. Magnetotelluric includes the magnetic component of the natural circuit.

Contents 1 Description 2 Patents 3 See also 4 Patents 5 Further reading 6 Reference 7 External links

Description

Telluric currents are induced in the Earth's crust and mantle by changes in the outer part of the Earth's magnetic field, which are usually caused by interactions between the solar wind and the ionosphere. They also result from thunderstorms. The electric potential on the Earth's surface can be measured at different points, enabling us to calculate the magnitudes and directions of the telluric currents and thence the Earth's conductance. Electric potential gradients caused by telluric currents are of the order of 10 microvolts per metre.

Both the telluric and magnetotelluric methods are used for exploring the structure beneath Earth's surface (such as in industrial prospecting). For mineral exploration the targets are conductive ore bodies. Other uses include exploration of geothermal fields, petroleum reservoirs, fault zones, ground water, magma chambers, and plate tectonic boundaries.

Patents

The United States Patent office has a division classification for geophysical electrical measuring devices of the telluric type (including magneto-telluric types).

See also

• High-voltage direct current
• Earth's magnetic field
• Ley line
• Wardenclyffe Tower Magnifying Transmitter
• Earth battery

Patents

• U.S. Patent 3361957 - Telluric current responsive device having spaced conductors for positioning adjacent the Earth's surface - D. L. Hings

Further reading

• Gideon, D. N., A. T. Hopper, and R. E. Thompson, "Earth current effects on buried pipelines : analysis of observations of telluric gradients and their effects". Battelle Memorial Institute and the American Gas Association. New York, 1970.

Reference

• "telluric current" A Dictionary of Earth Sciences. Ed. Ailsa Allaby and Michael Allaby. Oxford University Press, 1999.

External links

• Scripps Institution of Oceanography Marine EM Laboratory .
• Stephen, Jimmy, S. G. Gokarn, C. Manoj, S. B. Singh, "Effects of galvanic distortions on magnetotelluric data: Interpretation and its correction using deep electrical data". National Geophysical Research Institute. (PDF)
• Gummow, R. A., "Telluric and Ocean Current Effects on Buried Pipeline and their Cathodic Protection Systems". CORRENG Consulting Service, Inc. December 03, 2002.
• Sinha, M. C., et. al., "Applications of 3-Dimensional Electromagnetic Induction by Sources in the Ocean, ISO-3D". RTD Project, MAST III (Area C: Marine Technology). MAS3-CT97-0120

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