A telluric current (from Latin tellūs, "earth") is an electrical current which moves underground or through the sea. Telluric currents result from both natural causes and human activity, and the discrete currents interact in a complex pattern. The currents are extremely low frequency and travel over large areas at or near the surface of the Earth.

Description

Telluric currents are phenomena observed in the Earth's crust and mantle. In September of 1862, an experiment to specifically address Earth currents was carried out in the Munich Alps (Lamont, 1862). The currents are primarily induced by changes in the outer part of the Earth's magnetic field, which are usually caused by interactions between the solar wind and the magnetosphere or solar radiation effects on the ionosphere. Tellurics also result from thunderstorms. Telluric currents flow in the surface layers of the earth. 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. Telluric currents will move between each half of the terrestrial globe at all times. Telluric currents move equator-ward (daytime) and pole-ward (nighttime).

Both the telluric and magnetotelluric methods are used for exploring the structure beneath the 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. Telluric currents can be harnessed to produce a useful low voltage current by means of earth batteries. Such devices were used for telegraph systems in the United States as far back as 1859.

In Fiction

The main plot of the novel Foucault's Pendulum by Umberto Eco revolves around search of the Ombilicus Mundi (Latin: The Navel of the World), the mystic Center of The Earth which is supposed to be a certain point from were a person could control the energies and shapes of the earth thus reforming it at will. The novel takes this even further by suggesting that monuments like the Eiffel Tower are nothing more than giant antennae to catalyze these energies.

Telluric currents are also used as a means of travel by the woman Hsien-Ko and her minions in the Doctor Who "Missing Adventures" novel, The Shadow of Weng-Chiang, by David A McIntee.

Telluric currents – flowing along what are effectively ley lines – are discovered to be a means of mysterious communication in Thomas Pynchon's Mason and Dixon and are associated with the book's Chinese-Jesuit sub plot. As with Eco, cited above, Pynchon also reflects upon hollow earth theories in this work.

References and further readings

General

• "Telluric current" A Dictionary of Earth Sciences. Ed. Ailsa Allaby and Michael Allaby. Oxford University Press, 1999.
• "The Earth's Electrical Environment". US National Academies Press, Commission on Physical Sciences, Mathematics and Applications, 1986.
  • Louis J. Lanzerotti and Giovanni P. Gregori, "Telluric Currents: The Natural Environment and Interactions with Man-made Systems", Chapter 16.

Citations

• Krasnogorska, N. V., and Remizov, V. P., "Pulsations of the earth's electric field", Physico-mathematical and biological problems of effects of electromagnetic fields and ionization of air, Moscow, Nauka, pp. 49-56, 1975(Russian).
• Vanjan, L. P., "On the magnetospheric-ionospheric components of atmospheric electric field", Physico-mathematical and biological problems of electromagnetic field effects and air ionization. Proceedings of the All-Soviet Scientific Symposium, November 25-27, Yalta, Moscow, Nauka, Vol. 1, pp. 48-49, 1975. (Russian)
• Lamont, J. V., "Der Erdstrom und der Zusammen desselben mit dem Erdmagnetismus". Leopold-Voss-Verlag, Leipzig und Muenchen, 1862.

Other

• Wait, J.R., "On the relation between telluric currents and the earth’s magnetic field", Geophysics, 19, 281-289, 1954.
• 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.
• Seeley, Robert L., Tippens, C. L., and Hoover, Donald B., "Circuitry of the U.S.G.S. telluric profiler". U.S. Geological Survey open-file report ; 87-332, Denver, Colo. : U.S. Dept. of the Interior, Geological Survey.
• Berdichevskiĭ, Mark Naumovich, "Elektricheskaya razvedka metodom telluricheskikh tokov". Boston Spa, Yorkshire : National Lending Library for Science and Technology, 1963. LCCN 92140338 (Tr., "Electrical surveying by means of telluric currents"; Translation by J.E.S. Bradley)
• Hoover, Donald B., Pierce, H. A., and Merkel, D. C., "Telluric traverse and self potential data release in the vicinity of the Pinson Mine, Humboldt County, Nevada". U.S. Geological Survey open-file report; 86-341. U.S. Dept. of the Interior, Geological Survey, 1986.
• Marti, B. A., "Telluric Effects on a Buried Pipeline".
• Boteler, D.H., and W.H. Seager, "Telluric Currents: A Meeting of Theory and Observation"

External links

General

• "Electrical Conductivity : Models of the Crust and Mantle". [PDF]
• MTNet, Scientists engaged in the study of the Earth using electromagnetic methods, principally the magnetotelluric technique (magnetotellurics).
• 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
• "The Earth's Electrical Environment". Commission on Physical Sciences, Mathematics, and Applications, 1986. (nap.edu)