Electromagnetic Sounding of the Earth's Interior, Volume 40

Preface

Part 1 EM sounding methods

1. Global 3-D EM induction in the solid Earth and the oceans (A. Kuvshinov) 1.1. Forward problem formulation

2. 2. Basic 3-D Earth conductivity model
3. 3. Ocean effect in Sq variations
4. 4. Ocean effect of geomagnetic storms
5. 5. Magnetic fields due to ocean tides
6. 6. Magnetic fields due to ocean circulation
7. 7. Mapping conductivity anomalies in the Earth's mantle from space
8. 8. Conclusions

9. Magnetovariational method in deep geoelectrics (M. Berdichevsky, V. Dmitriev, N. Golubtsova, N. Mershchikova, and P. Pushkarev)

10. 1. Introduction
11. 2. On integrated interpretation of MV and MT data
12. 3. Model experiments
13. 4. MV-MT study of the cascadian subduction zone (EMSLAB experiment)

14. Shallow investigations by TEM-FAST technique: methodology and examples (P. Barsukov, E. Fainberg, E. Khabensky)

15. 1. Introduction
16. 2. Advantages of TEM in shallow depth studies
17. 3. On the TEM-FAST technology
18. 4. Transformation of E(t) data into ¡(h)
19. 5. One-dimensional inversion and TEM-FAST's resolution
20. 6. Joint inversion of TEM and DC soundings
21. 7. Side effects in TEM sounding

22. 7.1. Superparamagnetic effect in TEM

23. 7.2. Effect of induced polarization

24. 7.3. Antenna polarization effect (APE)

25. Seismoelectric methods of Earth study (B. Svetov)

26. 1. Seismoelectric effect (SE) of the first kind
27. 2. Seismoelectric effect of the second kind: historical outline and elements of theory
28. 3. Physical interpretation of seismoelectric phenomena
29. 4. Modeling of seismoelectric fields
30. 5. Laboratory studies of seismoelectric effects on rock samples
31. 6. Experimental field and borehole seismoelectric studies

Part 2 Forward modeling and inversion techniques 5. 3-D EM forward modeling using balance technique (V. Spichak) 5.1. Modern approaches to the forward problem solution 5.1.1. Methods of integral equations 5.1.2. Methods of differential equations 5.1.3. Mixed approaches 5.1.4. Analog (physical) modeling approaches 5.2. Balance method of EM fields computation in models with arbitrary conductivity distribution 5.2.1. Statement of the problem 5.2.2. Calculation of the electric field 5.2.3. Calculation of the magnetic field 5.2.4. Controlling the accuracy of the results 5.3. Method of the EM field computation in axially symmetric media 5.3.1. Problem statement 5.3.2. Basic equations 5.3.3. Boundary conditions 5.3.4. Discrete equations and their numerical solution 5.3.5. Code testing

6. 3-D EM forward modeling using integral equations (D. Avdeev)

7. 1. Introduction
8. 2. Volume integral equation method

9. 2.1. Traditional IE method

10. 2.2. Modified iterative dissipative method

11. 3. Model examples

12. 3.1. Induction logging problem

13. 3.2. Airborne EM example

14. 4. Conclusion

15. Inverse problems in modern magnetotellurics (V. Dmitriev, M. Berdichevsky)

16. 1. Three features of multi-dimensional inverse problem

17. 1.1. Normal background

18. 1.2. On detailness of multi-dimensional inversion

19. 1.3. On redundancy of observation data

20. 2. Three questions of Hadamard

21. 2.1. On the existence of a solution to the inverse problem

22. 2.2. On the uniqueness of the solution to the inverse problem

23. 2.3. On the instability of the inverse problem

24. 3. Magnetotelluric and magnetovariational inversions in the light of Tikhonov's theory of ill-posed problems

25. 3.1. Conditionally well-posed formulation of inverse problem

26. 3.2. Optimization method

27. 3.3. Regularization method

28. Joint robust inversion of magnetotelluric and magnetovariational data (Iv.M. Varentsov)

29. 1. Adaptive parametrization of a geoelectric model

30. 1.1. A background structure and windows to scan anomalies

31. 1.2. A priori model structure and constrains

32. 1.3. Window with correlated resistivities of inversion cells

33. 1.4. Window with finite functions

34. 2. Inverted and modelling data
35. 3. Inversion as a minimization problem

36. 3.1. Minimizing functional

37. 3.2. Robust misfit metric

38. 3.3. Cycles of Tikhonov's minimization

39. 3.4. Newtonian minimization techniques

40. 3.5. Solution of linear newtonian system and choice of scalar newtonian step

41. 3.6. Multi-level adaptive stabilization

42. 3.7. Post-inversion analysis

43. 4. Study of inversion algorithms using synthetic data sets

44. 4.1. Comparison of three model parameterization schemes in 2-D inversion

45. 4.2. 2-D inversion with numerous finite functions

46. 4.3. 3-D inversion example

47. 4.4. Resolution of a system of local conductors using the CR-parameterization

48. 4.5. Reduction of strong data noise and static shift

49. 5. Conclusions

50. Artificial neural network inversion of EM data (V. Spichak) 9.1. Backpropagation technique

51. 2. Creation of teaching and testing data pools
52. 3. Effect of the EM data transformations on the quality of the parameters' recognition

53. 3.1. Types of the activation function at hidden and output layers

54. 3.2. Number of the neurons in a hidden layer

55. 3.3. Effect of an extra hidden layer

56. 3.4. Threshold level

57. 4. Effect of the input data type
58. 5. Effect of the volume and structure of the training data pool
    6. 5.1. Effect of size
    7. 5.2. Effect of structure
59. 6. Extrapolation ability of ANN
60. 7. Noise treatment
61. 8. Case history: ANN reconstruction of the Minou fault parameters

62. 8.1. Geological and geophysical setting

63. 8.2. CSAMT data acquisition and processing

64. 8.3. 3-D imaging Minou fault zone using 1-D and 2-D inversion

65. 8.4. ANN reconstruction of the Minou geoelectrical structure

66. 8.5. Discussion and conclusions

Part 3 Data processing, analysis and interpretation
10. Arrays of simultaneous electromagnetic soundings: design, data processing and analysis (Iv. M. Varentsov) 10.1. Simultaneous systems for natural EM fields observation 10.2 Multi-site schemes for estimation of transfer operators 10.3. Temporal stability of transfer operators 10.4. Methods for the analysis and interpretation of simultaneous EM data 10.5. Conclusions 11. Magnetotelluric field transformations and their application in interpretation (V. Spichak)

11.1. Linear relations between MT field components 11.2. Point transforms of MT data 11.2.1. Impedance transforms 11.2.2 Apparent resistivity type transforms 11.2.3. Induction and perturbation vectors 11.3. Examples of the use of MT field point transforms for the interpretation 11.3.1. Dimensionality indicators 11.3.2. Local and regional anomalies 11.3.3. Constructing resistivity images in the absence of prior information 11.4. Integral transforms 11.4.1. Division of the MT field into parts 11.4.2. Transformation of the field components into each other 11.4.3. Synthesis of synchronous MT field from impedances and induction vectors

12. Modeling of magnetotelluric fields in 3-D media (V. Spichak)

13. 1. A feasibility study of MT method application in hydrocarbon exploration

14. 1.1. Statement of the problem

15. 1.2. Numerical modeling

16. 2. Testing hypotheses of the geoelectric structure of the Transcaucasian region from magnetotelluric data

17. 2.1. Geological and geophysical characteristics of the region

18. 2.2. Alternative conductivity models

19. 2.3. Numerical modeling of magnetotelluric fields

20. 2.4. Conclusions

21. 3. MT imaging internal structure of volcanoes

22. 3.1. Simplified model of the volcano

23. 3.2. Synthetic MT pseudosections

24. 3.3. Methodology of interpretation of the MT data measured over the relief surface

25. 4. Simulation of MT monitoring of the magma chamber conductivity

26. 4.1. Geoelectric model of a central type volcano

27. 4.2. Detection of the magma chamber by MT data

28. 4.3. Estimation of MT data resoling power with respect to the conductivity variations in the magma chamber

29. 4.4. “Guidelines” for MT monitoring electric conductivity in a magma chamber

30. 5. Simulation of MT monitoring the ground water salinity

31. 5.1. Statement of the problem

32. 5.2. Modeling of the salt water intrusion zone mapping by audio MT data

33. Regional magnetotelluric explorations in Russia (V. Bubnov, E. Aleksanova, M. Berdichevsky, P. Pushkarev, A.Yakovlev, D.Yakovlev)

34. 1. Introduction
35. 2. Observation technology
36. 3. MT-data processing, analysis and interpretation
37. 4. Case histories:

38. 4.1. East-European craton

39. 4.2. Caucasus, the Urals, Siberia and North East Russia

40. EM studies at seas and oceans (N. Palshin)

41. 1. Conductivity structure of sea and ocean floor

42. 1.1. Background conductivity structure of the ocean crust and upper mantle

43. 1.2. Principle objectives of marine EM studies

44. 2. Instrumentation for marine EM studies

45. 2.1. Seafloor controlled source frequency and transient EM sounding

46. 2.2. Measurements of variations of natural EM fields on the seafloor

47. 3. Some results of EM sounding in seas and oceans

48. 3.1. Studies of gas hydrates in seabed sediments of continental slopes

49. 3.2. Studies of buried salt dome-like structures

50. 3.3. The Reykjanes Axial Melt Experiment: Structural Synthesis from Electromagnetics and Seismics (RAMESSES project)

51. 3.4. Seafloor MT soundings of the Eastern-Pacific rise at 9º50'N

52. 3.5. Mantle Electromagnetic and Tomography Experiment (MELT)

53. 4. Deep seafloor EM studies in the Northwestern Pacific

Based on lectures given in the First Russian School-Seminar on electromagnetic soundings of the Earth held in Moscow on 15th November, 2003, this book acquaints scientists and technologists with the latest achievements in theory, techniques and practical applications of the methods of electromagnetic sounding. This three part text covers the methods considered for Earth electromagnetic sounding on a global, regional, and local scale; modern methods for solving forward and inverse problems of geoelectrics, particularily contemporary approaches to the EM data modeling and interpretation in the class of three-dimensional models; and the results of regional EM on-land and sea soundings

• Presents theoretical and methodological findings, as well as examples of applications of recently developed algorithms and software in solving practical problems
• Describes the practical importance of electromagnetic data through enabling discussions on a construction of a closed technological cycle, processing, analysis and three-dimensional interpretation
• Updates current findings in the field, especially with MT, magnetovariational and seismo-electriccal methods and the practice of 3D interpretaions

geochemists, geophysists