Electromagnetic Sounding of the Earth's Interior (eBook)

Cover 1
Electromagnetic Sounding of the Earth’s Interior 4
Copyright page 5
Contents 6
Preface 14
Part I: EM Sounding Methods 18
Chapter 1. Global 3-D EM Induction in the Solid Earth and the Oceans 20
1.1. Forward Problem Formulation 21
1.2. Basic 3-D Earth Conductivity Model 22
1.3. Ocean Effect in Sq Variations 24
1.4. Ocean Effect of Geomagnetic Storms 26
1.5. Magnetic Fields due to Ocean Tides 30
1.6 Magnetic Fields due to Ocean Circulation 33
1.7. Mapping Conductivity Anomalies in the Earth’s Mantle From Space 35
1.8. Conclusions 38
References 38
Chapter 2. Magnetovariational Method in Deep Geoelectrics 44
2.1. Introduction 44
2.2. On Integrated Interpretation of MV and MT Data 47
2.3. Model Experiments 50
2.4. MV–MT Study of the Cascadian Subduction Zone (EMSLAB Experiment) 55
References 68
Chapter 3. Shallow Investigations by TEM-FAST Technique: Methodology and Examples 72
3.1. Introduction 72
3.2. Advantages of TEM in Shallow Depth Studies 73
3.3. On The TEM-FAST Technology 74
3.4. Transformation of E(t) Data into .(h) 76
3.5. One-Dimensional Inversion and TEM-FAST’s Resolution 78
3.6. Joint Inversion of TEM and DC Soundings 80
3.7. Side Effects in TEM Sounding 84
References 93
Chapter 4. Seismoelectric Methods of Earth Study 96
4.1. Seismoelectric Effect of the First Kind 96
4.2. Seismoelectric Effect of the Second Kind: Historical Outline and Elements of Theory 97
4.3. Physical Interpretation of Seismoelectric Phenomena 100
4.4. Modeling of Seismoelectric Fields 103
4.5. Laboratory Studies of Seismoelectric Effects on Rock Samples 107
4.6. Experimental Field and Borehole Seismoelectric Studies 113
References 117
Part II: Forward Modeling and Inversion Techniques 120
Chapter 5. 3-D EM Forward Modeling Using Balance Technique 122
5.1. Modern Approaches to the Forward Problem Solution 123
5.2. Balance Method of EM Fields Computation in Models with Arbitrary Conductivity Distribution 133
5.3. Method of the EM Field Computation in Axially Symmetric Media 141
References 151
Chapter 6. 3-D EM Forward Modeling Using Integral Equations 160
6.1. Introduction 160
6.2. Volume Integral Equation Method 161
6.3. Model Examples 168
6.4. Conclusion 169
References 169
Chapter 7. Inverse Problems in Modern Magnetotellurics 174
7.1. Three Features of Multi-Dimensional Inverse Problem 176
7.2. Three Questions of Hadamard 180
7.3. MT and MV Inversions in the Light of Tikhonov’s Theory of Ill-Posed Problems 192
References 200
Chapter 8. Joint Robust Inversion of Magnetotelluric and Magnetovariational Data 202
8.1. Adaptive Parameterization of a Geoelectric Model 203
8.2. Inverted and Modeling Data 205
8.3. Inversion as a Minimization Problem 207
8.4. Study of Inversion Algorithms Using Synthetic Datasets 214
8.5. Conclusions 232
References 233
Chapter 9. Neural Network Reconstruction of Macro-Parameters of 3-D Geoelectric Structures 236
9.1. Backpropagation Technique 237
9.2. Creation of Teaching and Testing Data Pools 240
9.3. Effect of the EM Data Transformations on the Quality of the Parameters’ Recognition 241
9.4. Effect of the Input Data Type 246
9.5. Effect of the Volume and Structure of the Training Data Pool 249
9.6. Extrapolation Ability of ANN 255
9.7. Noise Treatment 256
9.8. Case History: ANN Reconstruction of the Minou Fault Parameters 259
References 270
Part III: Data Processing, Analysis, Modeling and Interpretation 274
Chapter 10. Arrays of Simultaneous Electromagnetic Soundings: Design, Data Processing and Analysis 276
10.1. Simultaneous Systems for Natural EM Fields Observation 276
10.2. Multi-Site Schemes for Estimation of Transfer Operators 279
10.3. Temporal Stability of Transfer Operators 281
10.4. Methods for the Analysis and Interpretation of Simultaneous EM Data 283
10.5. Conclusions 287
References 288
Chapter 11. Magnetotelluric Field Transformations and their Application in Interpretation 292
11.1. Linear Relations Between MT Field Components 293
11.2. Point Transforms of MT Data 294
11.3. Examples of the use of MT Field Point Transforms for the Interpretation 308
11.4. Integral Transforms 315
References 322
Chapter 12. Modeling of Magnetotelluric Fields in 3-D Media 330
12.1. A Feasibility Study of MT Method Application in Hydrocarbon Exploration 331
12.2. Testing Hypotheses of the Geoelectric Structure of the Transcaucasian Region From MT Data 338
12.3. MT Imaging Internal Structure of Volcanoes 348
12.4. Simulation of MT Monitoring of the Magma Chamber Conductivity 355
12.5. Simulation of MT Monitoring the Ground Water Salinity 361
References 365
Chapter 13. Regional Magnetotelluric Explorations in Russia 368
13.1. Introduction 368
13.2. Observation Technology 370
13.3. MT-Data Processing, Analysis and Interpretation 371
13.4. Case Histories 373
13.5. Conclusion 383
References 383
Chapter 14. EM Studies at Seas and Oceans 386
14.1. Conductivity Structure of Sea and Ocean Floor 387
14.2. Instrumentation for Marine EM Studies 388
14.3. Some Results of EM Sounding in Seas and Oceans 392
14.4. Deep Seafloor EM Studies in the Northwestern Pacific 397
References 399
Subject Index 402