Preface ...................................................... xiii
Acknowledgments ............................................... xiv
1 Introduction ................................................. 1
1.1 Workflow ................................................ 2
1.2 Some applications of near-surface geophysics ............ 3
1.3 Communication of uncertainties .......................... 9
1.4 Outline of the book .................................... 11
2 Data analysis ............................................... 12
2.1 Information ............................................ 12
2.2 Sensors ................................................ 14
2.3 Frequency response ..................................... 15
2.4 Discrete Fourier transform ............................. 17
2.5 Filtering .............................................. 22
2.6 Convolution ............................................ 24
2.7 Sampling and aliasing .................................. 26
2.8 Data windows and spectral analysis ..................... 26
2.9 De-spiking time series ................................. 28
2.10 Continuous wavelet transform (CWT) .................... 30
Problems .................................................... 33
3 Magnetics ................................................... 34
3.1 Introduction ........................................... 34
3.2 Fundamentals ........................................... 36
3.3 Instrumentation ........................................ 41
3.4 Magnetic gradiometry ................................... 44
3.5 Geomagnetic field ...................................... 44
3.6 Total-field anomaly .................................... 49
3.7 Interpretation of magnetic anomalies ................... 49
3.8 Reduction to the pole .................................. 52
3.9 Depth rules ............................................ 57
3.10 Magnetic properties of rocks, soils, and buried
steel objects .......................................... 57
3.11 Remanent magnetization ................................. 59
3.12 Image-enhancement filters .............................. 60
3.13 Upward continuation .................................... 62
3.14 Euler and Werner deconvolution ......................... 64
3.15 Illustrative case histories ............................ 67
Problems .................................................... 68
4 Electrical resistivity method ............................... 70
4.1 Introduction ........................................... 71
4.2 Fundamentals ........................................... 72
4.3 Sensitivity functions .................................. 78
4.4 Multi-layer models ..................................... 80
4.5 Azimuthal resistivity .................................. 84
4.6 Resistivity pseudosections ............................. 87
4.7 Electrical-resistivity tomography (ERT) ................ 87
4.8 Electrical properties of rocks ......................... 90
4.9 Electrical-hydraulic field-scale correlation studies ... 93
4.10 Optimal electrode placement ............................ 96
4.11 Underwater resistivity techniques ...................... 99
4.12 Illustrative case histories ........................... 100
Problems ................................................... 102
5 Induced polarization and self-potential .................... 104
5.1 Induced polarization (IP): introduction ............... 105
5.2 Phenomenological resistivity dispersion models ........ 107
5.3 Electrode, membrane, and interfacial polarization ..... 109
5.4 IP response and subsurface geological processes ....... 111
5.5 Non-polarizing electrodes ............................. 112
5.6 IP illustrated case history ........................... 112
5.7 Self-potential (SP): introduction ..................... 114
5.8 Physical mechanisms ................................... 115
5.9 Interpretation of SP measurements ..................... 117
5.10 Continuous wavelet transform analysis ................. 119
5.11 SP illustrated case history ........................... 123
Problem .................................................... 124
6 Seismic reflection and refraction .......................... 125
6.1 Introduction .......................................... 125
6.2 Stress and strain ..................................... 128
6.3 Wave motion ........................................... 131
6.4 Seismic waves and elastic moduli ...................... 132
6.5 Seismic velocity of geomaterials ...................... 134
6.6 Reflection and refraction at an interface ............. 136
6.7 Diffraction ........................................... 139
6.8 Analysis of idealized reflection seismograms .......... 139
6.9 Vertical and horizontal resolution .................... 144
6.10 Common midpoint profiling ............................. 148
6.11 Dip moveout ........................................... 150
6.12 Attenuation ........................................... 153
6.13 Seismic refraction .................................... 155
6.14 Practical considerations .............................. 160
6.15 Seismic data processing ............................... 164
6.16 Ray-path modeling ..................................... 174
6.17 Illustrated case studies .............................. 177
Problems ................................................... 180
7 Seismic surface-wave analysis .............................. 182
7.1 Rayleigh waves ........................................ 182
7.2 Dispersion ............................................ 184
7.3 Rayleigh-wave propagation in a multi-layer system ..... 185
7.4 Spectral analysis of surface waves (SASW) ............. 187
7.5 Multichannel analysis of surface waves (MASW) ......... 190
7.6 Inversion of R-wave dispersion characteristics ........ 192
7.7 Micro tremor and passive studies ...................... 195
7.8 Illustrated case histories ............................ 197
8 Electromagnetic induction .................................. 200
8.1 Introduction .......................................... 200
8.2 Fundamentals .......................................... 204
8.3 The skin effect ....................................... 206
8.4 Inductively coupled LR circuits ....................... 208
8.5 Terrain conductivity meters ........................... 213
8.6 Time-domain EM induction .............................. 219
8.7 Finite-source excitation of a layered Earth ........... 223
8.8 Plane-wave excitation methods: VLF, RMT, CSMT ......... 224
8.9 Airborne electromagnetics ............................. 228
8.10 EM responses of rough geological media ................ 230
8.11 Anisotropy ............................................ 232
8.12 Illustrated case histories ............................ 234
Problems ................................................... 238
9 Ground-penetrating radar ................................... 239
9.1 Fundamentals .......................................... 241
9.2 Dielectric constant and electrical conductivity ....... 245
9.3 Dielectric properties of rocks and soils .............. 247
9.4 Resolution ............................................ 250
9.5 Data acquisition ...................................... 250
9.6 Basic GPR data processing ............................. 252
9.7 Advanced GPR data processing .......................... 256
9.8 Electromagnetic plane waves ........................... 257
9.9 Plane-wave reflection from an interface ............... 261
9.10 Analysis of thin beds ................................. 264
9.11 GPR antennas .......................................... 265
9.12 GPR radiation patterns ................................ 268
9.13 Target polarization ................................... 270
9.14 GPR guided waves ...................................... 272
9.15 GPR illustrative case histories ....................... 275
Problems ................................................... 277
10 Emerging techniques ........................................ 279
10.1 Surface nuclear magnetic resonance .................... 279
10.2 Time-lapse microgravity ............................... 283
10.3 Induced-seismicity studies ............................ 285
10.4 Landmine discrimination ............................... 286
10.5 Passive GPR interferometry ............................ 289
10.6 Seismoelectric coupling ............................... 292
11 Linear inversion ........................................... 296
11.1 Introduction .......................................... 296
11.2 Linear-parameter estimation ........................... 299
11.3 Least-squares solution ................................ 300
11.4 Example: near-surface magnetization ................... 301
11.5 Example: deconvolution ................................ 304
11.6 Data covariance ....................................... 304
11.7 The null space ........................................ 306
11.8 The minimum-norm solution ............................. 306
11.9 The trade-off curve ................................... 308
11.10 Regularization ....................................... 309
11.11 Example: EM loop-loop sounding ....................... 311
11.12 Singular-value decomposition ......................... 313
Problems ................................................... 316
12 Non-linear inversion: local methods ........................ 317
12.1 Introduction .......................................... 317
12.2 Steepest-descent method ............................... 318
12.3 Non-linear least-squares method ....................... 320
12.4 Levenberg-Marquardt method ............................ 322
12.5 Quasi-Newton methods .................................. 323
12.6 Conjugate-gradient method ............................. 325
12.7 Example: seismic traveltime tomography ................ 328
12.8 Bayesian inversion .................................... 331
12.9 Auxiliary sensitivity analysis ........................ 333
Problems ................................................... 336
13 Non-linear inversion: global methods ....................... 337
13.1 Markov chain Monte Carlo (MCMC) method ................ 338
13.2 Simulated-annealing (SA) method ....................... 340
13.3 Genetic-algorithm (GA) method ......................... 344
13.4 Neural-network (NN) methods ........................... 346
13.5 The self-organizing map (SOM) ......................... 354
Problem .................................................... 358
Appendix A: Shannon sampling theorem .......................... 359
Appendix B: Solution of Laplace's equation in spherical
coordinates .................................... 363
Appendix C: The linear z-p transformation of seismic data ..... 367
Appendix D: Horizontal loop over a conducting halfspace ....... 370
Appendix E: Radar ТЕ waveguide mode equations ................. 377
References .................................................... 379
Index ......................................................... 400
The color plates can be found between pages 242 and 243
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