Abstract
The relations between galvanic and inductive electromagnetic excitation of 3-D asthenospheric conducting zones are considered. Mathematical modeling with the application of integral equations shows that the rather intense magnetotelluric anomalies reflecting the topography of the conducting asthenosphere arise via the galvanic channel, which has two branches: (1) the lithospheric branch (an electric current flows from the sedimentary cover into the lithosphere and concentrates in uplifts of the conducting asthenosphere), which is inactive in the case of a very high resistivity of the lithosphere (the screening effect), and (2) the mantle branch (the deep mantle current flows from below into uplifts of the conducting asthenosphere), which is free from the screening effect of a high resistivity lithosphere. In previous works, the mantle branch of the galvanic channel was erroneously associated with local induction in uplifts of the asthenosphere. According to modern estimates, local induction in the asthenosphere generates weak magnetotelluric anomalies that cannot be reliably measured.
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References
L. M. Al’pin, Field Theory (Nedra, Moscow, 1966) [in Russian].
D. B. Avdeev, A. V. Kuvshinov, O. V. Pankratov, and G. A. Newman, “High-Performance Three-Dimensional Electromagnetic Modelling Using Modified Neumann Series,” J. Geomagn. Geoelectr. 49, 1519–1539 (1997).
M. N. Berdichevsky, V. I. Dmitriev, and N. A. Lebedeva, “Analysis of Electromagnetic Anomalies Using Film Models,” Izv. Akad. Nauk SSSR, Fiz. Zemli, No. 3, 43–51 (1991).
M. N. Berdichevsky, L. L. Vanyan, I. V. Egorov, et al., “Resolution Analysis of Electromagnetic Sounding,” Fiz. Zemli, No. 1, 119–128 (1992).
M. N. Berdichevsky and V. I. Dmitriev, Models and Methods of Magnetotellurics (Springer, Berlin, 2008).
N. V. Dortman and S. M. Fiveg, “Electrical Resistivity of Minerals and Rocks,” in Handbook of Petrophysics, Ed. by N. V. Dortman (Nedra, Moscow, 1992), pp. 183–204 [in Russian].
I. V. Egorov, “Comparison of Two-Dimensional and Axisymmetric Three-Dimensional Magnetotelluric Anomalies,” Izv. Akad. Nauk SSSR, Fiz. Zemli, No. 6, 106–112 (1987).
A. A. Kaufman, Geophysical Field. Theory and Method. Part A (Academic, San Diego, 1992).
A. A. Kaufman, Geophysical Field. Theory and Method. Part B (Academic, San Diego, 1994).
W. R. Smythe, Static and Dynamic Electricity (New York, 1950).
L. L. Vanyan, I. V. Egorov, and A. P. Shilovsky, “Magnetotelluric Excitation of Deep Conducting Zones,” in Electromagnetic Sounding (MGU, Moscow, 1981), p. 77 [in Russian].
L. L. Vanyan, I. V. Egorov, and A. P. Shilovsky, “Inductive Excitation of Three-Dimensional Electrical Conductivity Anomalies of the Crust and Asthenosphere,” in Electromagnetic Sounding (IZMIRAN, Moscow, 1984), p. 14 [in Russian].
L. L. Vanyan, I. V. Egorov, and A. P. Shilovsky, “Electromagnetic Excitation of Axisymmetric Asthenospheric Zones,” Izv. Akad. Nauk SSSR, Fiz. Zemli, No. 6, 67–73 (1988).
L. L. Vanyan, I. V. Egorov, and A. P. Shilovsky, “Induction Excitation of Deep 3-D Conducting Zones,” Geophys. J. Int. 105, 295–300 (1991).
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Original Russian Text © M.N. Berdichevsky, R.F. Logunovich, 2008, published in Fizika Zemli, 2008, No. 7, pp. 11–20.
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Berdichevsky, M.N., Logunovich, R.F. Electromagnetic excitation of asthenospheric conducting zones. Izv., Phys. Solid Earth 44, 527–536 (2008). https://doi.org/10.1134/S1069351308070021
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DOI: https://doi.org/10.1134/S1069351308070021