cover

Gottfried Porstendorfer:

Principles of Magneto-Telluric Prospecting

Ed.: Geza Kunetz; D.S. Parasnis

1975. VIII, 118 pages, 71 figures, 3 tables, 17x24cm, 440 g
Language: English

(Geoexploration Monographs, Number 5)

ISBN 978-3-443-13007-7, bound, price: 33.00 €

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Keywords

deep prospectingmathematical developmentselectromagnetic fiieldspolarisationdigital processing

Contents

Content Description top ↑

The great increase in the international literature and the quick development of the field and processing techniques of magneto-telluric methods for investigation of the earth's crust and mantle stimulated the desire to try a generalisation of the theoretical and practical works, inherent in the classical methods "Tellurics," "Magneto-Tellurics" and "Geomagnetic Deep Sounding."

In particular, the author could use here the great experience of Soviet scientists. Lateral inhomogeneities distort the magneto-telluric fields over long distances, and so the main problem with which the book is concerned is to present the methods of investigation and results of computations or measurements on models representing lateral inhomogeneities or anisotropic structures. The book includes the demonstration of the possibilities of computerized methods, without neglecting the older, manual processing procedures. Measuring instruments, field procedures and examples of case histories are only briefly treated. The kind of demonstration grew from the author's lectures at the Mining Academy Freiberg. It was sometimes necessary to use generalizations, to keep complicated mathematical developments out of the book and to desist from descriptions of too many single papers. On the other hand, a large number of illustrative examples in the form of figures and references to the international bibliography are given.

Contents top ↑

1. Introduction 1
Aim of electromagnetic investigations in deep prospecting, History
2. The natural electromagnetic field of the earth 7
Sources of natural electromagnetic variations, Character and spectrum of the natural electromagnetic field
3. Basic theoretical problems 15
Incidence of plane harmonic electromagnetic waves on a plane surface bounding geological media of any shape. Quantitative relations of the magneto-telluric field components to the structure and the resistivities of the geological media
4. Processing of field records 65
Determination of the elements of the tensor relation between the field components by complex polarization vectors. Determination of the polar diagrams for the tensor coefficients. Magnetic and electric field ellipses
5. Digital processing of field records 81
Digital processing by time-domain filters, Digital processing by Fourier analysis, Digital processing by statistical frequency analysis, Digital processing of the elements of the tensor relation between the field components, Interpretation of magneto-telluric sounding curves by means of computer
6. Instruments and methods for field recording 95
Induction coils, Microvariometer with photoelectric feedback, Electron precession magnetometer, Electrode arrangement for the measurement of the electric field, Recording instruments
7. Geological examples 100
Tellurics, Magneto-tellurics, Geomagnetic deep sounding, AFMAG
8. Concluding remarks on the accuracy of magneto-telluric investigations and interpretations 111
Literatur, Index 112