Magnetotelluric calculations for the interaction of polarized fields with anisotropic layered media

Praus, Oldřich; Petr, Václav

doi:10.1139/e69-070

Cited by 15 publications

(9 citation statements)

References 5 publications

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“…The squares of the off diagonal elements of this tensor are equal to the apparent resistivities in the principal axes of the impedance tensor at the Earth's surface. The modified impedance tensor, discussed here, differs from the so-called apparent resistivity tensor (Praus & Petr 1969). While the latter is doubtless a useful quantity for discussion and analysis, it unfortunately is not a tensor and does not behave as such.…”

Section: (26)mentioning

confidence: 82%

“…A second example was calculated, using a model considered by Praus & Petr (1969). In this model, two layers overlie a half space.…”

Section: Examplesmentioning

confidence: 99%

“…Most of the cited papers considered only the simplest theoretical cases, such as a model consisting of a two-dimensional half space or an anisotropic layer over an half space. More general models, consisting of a set of anisotropic, laterally homogeneous layers, were considered by OBrien & Morrison (1967), Praus & Petr (1969), Rankin & Reddy (1969), and Reddy & Rankin (1971). These authors obtained methods for computing the impedance tensor by carrying through the coefficients of the upgoing and downgoing E and H waves, starting at the lower half space, and working up to the surface of the Earth.…”

Section: Introductionmentioning

confidence: 99%

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Theory for Magnetotelluric Observations on the Surface of a Layered Anisotropic Half Spaces†

Loewenthal

Landisman

2009

Geophysical Journal of the Royal Astronomical Society

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A magnetotelluric model is considered which consists of a vertical cylinder comprised of horizontal layers, each having a conductivity that is homogeneous both laterally and vertically. There are thus no lateral variations in the magnetic, electric, and current vector fields within the vertical cylinder centered about the observation site. The layer conductivities may be either isotropic, symmetrically anisotropic, or asymmetrically anisotropic in arbitrary vertical sequence, with the horizontal anisotropies oriented at any azimuth about the vertical axis.The intrinsic properties of the impedance tensor in the layered half space permit the tensor to be propagated through the layers without resort to the calculation of the associated electric and magnetic field vectors, as in previous works. The resulting new algorithm permits the calculation to be performed with second rank matrices instead of fourth rank as previously required, with a considerable improvement in speed and accuracy.The calculation of a number of these models illustrates the need for observations that span a sufficiently broad range of periods. Computed results, when considered over a narrow bandwidth, are shown to greatly resemble those for completely dis-similar models.The new algorithm is also used for downward propagation of the impedance tensor at the observational surface, so that it is possible to recover the vertical distribution of conductivity under favourable circumstances. Theory for magnetotelluric observations'"-2 T H~-~ U,l~l U , ( Z ) l a ' e n -i n-iU,n-t n-i u,, 'I c$)u,~') en 197 Jx Ju = J zought to yield satisfactory results for many cases where the magnetotelluric method may be expected to yield useful data.The conductivity tensor IJ is considered here to be generally an anisotropic tensor, which makes the model more realistic in two respects:

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Section: (26)mentioning

confidence: 82%

“…A second example was calculated, using a model considered by Praus & Petr (1969). In this model, two layers overlie a half space.…”

Section: Examplesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Theory for Magnetotelluric Observations on the Surface of a Layered Anisotropic Half Spaces†

Loewenthal

Landisman

2009

Geophysical Journal of the Royal Astronomical Society

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“…The anisotropic conductivity is one of the dominating features in the crust and upper mantle. The importance of conductivity anisotropy in the interpretation of magnetotelluric data has been shown by a number of workers (Chetaev 1960, Mann 1965, Negi and Saraf 1981, O'Brien and Morrison 1967, Praus and Peter 1969, Sinha 1969. Reddy and Rankin (1971) have obtained a theoretical solution for the magnetotelluric effect in the case of a multilayered earth with each layer containing inclined anisotropy and with the " strike " of anistropy oriented at an arbitrary angle to the measuring directions.…”

Section: Introductionmentioning

confidence: 99%

Effect of Inclined Anisotropic Substratum on Magnetotelluric Response*

Singh¹

1985

Geophysical Prospecting

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SINGH, R.P. 1985, Effect of Inclined Anisotropic Substratum on Magnetotelluric Response, Geophysical Prospecting 33,369-376.In tectonically active regions electrical conductivity anisotropies are the dominating features. The importance of conductivity anisotropy in the interpretation of magnetotelluric data is well known. In the present study numerical results presented which show the effect of a substratum with inclined anisotropy on the magnetotelluric response. The pronounced change on the magnetotelluric response is found for the models in which the substratum underlies (i) conductive and (ii) resistive overburden.

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“…Non-isotropic structures were introduced as a possible explanation for the dependence of apparent resistivity with orientation (Cantwell 1960) and were investigated in many theoretical and field studies, e.g. O'Brien & Morrison (1967), Praus & Petr (1969), Rankin & Reddy (1969) and Reddy & Rankin (1971).…”

Section: Introductionmentioning

confidence: 99%

The Backus--Gilbert theory for piecewise continuous structures with variable discontinuity levels and its application to the magnetotelluric inverse problem

Abramovici

Baumgarten

1985

Geophysical Journal International

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The Backus-Gilbert theory is extended to the case when the models are piecewise continuous vector functions of depth with variable discontinuity locations. In addition, some of the layers may be represented by linear combinations of known functions. For such layers only a finite number of discrete parameters is to be determined. The iterative process for obtaining a model satisfying the data is convergent, the numerical procedure by which the iterations are performed being equivalent to the method of spectral decomposition for continuous structures. The method of obtaining the Frkchet kernels by using the first perturbation of the differential system satisfied by the corresponding functionals is shown to be valid.The theory is applied to the magnetotelluric problem, Frkchet kernels being calculated for isotropic and non-isotropic structures.A few numerical examples are described.

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Magnetotelluric calculations for the interaction of polarized fields with anisotropic layered media

Cited by 15 publications

References 5 publications

Theory for Magnetotelluric Observations on the Surface of a Layered Anisotropic Half Spaces†

Theory for Magnetotelluric Observations on the Surface of a Layered Anisotropic Half Spaces†

Effect of Inclined Anisotropic Substratum on Magnetotelluric Response*

The Backus--Gilbert theory for piecewise continuous structures with variable discontinuity levels and its application to the magnetotelluric inverse problem

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