Electromagnetic Depth Soundings

1. Front Matter

   Pages i-vii

   PDF

2. Electromagnetic Sounding Methods—Introduction and History

   • George V. Keller

   Pages 1-18

3. Electrical Prospecting with the Transient Magnetic Field Method

   • L. L. Vanyan, L. Z. Bobrovnikov

   Pages 19-124

4. Fundamentals of Electromagnetic Sounding

   • L. L. Vanyan

   Pages 125-200

5. Concerning Some Causes for the Distortion of Transient Sounding Curves

   • L. L. Vanyan, V. M. Davidov, E. I. Terekhin

   Pages 201-207

6. Concerning the Factors Distorting Frequency Sounding Curves

   • A. N. Kuznetsov

   Pages 209-215

7. Four-Layer Master Curves for Frequency Electromagnetic Sounding

   • L. L. Vanyan, G. M. Morozova, V. L. Loshenitzina, E. I. Terekhin, A. I. Shtimmer

   Pages 217-312

10.------------------------, 10.------------------------. N ::IE ~ w ~ '" "'0.1 \~ 0 M z SIDE VIEW PLAN VIEW 0.01 LI --'---'---LLL-'---LLLlI ~-L---"---LLL..ll..L.LJ'-':';;' 0.01 1 100 10 100 fr Fig. 1. The behavior of the magnetic and electric fields from a vertical magnetic dipole source at the surface of the earth (after Wait [1951,1955]). earth, the experimental curve so plotted should have the same shape as a portion of the ap­ propriate theoretical curve, but with the ordinates and abscissas shifted by an amount dependent on the resistivity. The conductivity can be determined from the amount of shift between the field data and the theoretical curve. A detailed description of the curve matching procedure is found in a text by Keller and Frischknecht (1966). The curve matching procedure, though used, has several disadvantages. Measurements must be made over a diagnostic portion of the theoretical curve, one in which there is some curvature, so that the amount of shift required to make a match can be determined uniquely. This means that the approximate conductivity of the earth must be known when measurements are made. Secondly, determination of a single value of conductivity requires measurements made over a wide range of frequencies. This would appear to be wasteful of data, inasmuch as the equations indicate that a single measurement at a single frequency should be enough to de­ termine conductivity.

• ETA
• Matching
• behavior
• boundary element method
• earth
• electromagnetic
• equation
• experiment
• field
• fields
• frequency
• measurement
• resistivity
• surface
• waste

• Moscow Geological Exploration Institute, Russia

  L. L. Vanyan

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