An Introduction to Applied and Environmental Geophysics, 2nd Edition

Preface to the 2nd Edition xi

Acknowledgements xiii

1 Introduction 1

1.1 What are ‘applied’ and ‘environmental’ geophysics? 1

1.2 Geophysical methods 3

1.3 Matching geophysical methods to applications 5

1.4 Planning a geophysical survey 5

1.5 Geophysical survey design 9

2 Gravity Methods 19

2.1 Introduction 19

2.2 Physical basis 19

2.3 Measurement of gravity 24

2.4 Gravity meters 26

2.5 Corrections to gravity observations 34

2.6 Interpretation methods 45

2.7 Applications and case histories 59

3 Geomagnetic Methods 83

3.1 Introduction 83

3.2 Basic concepts and units of geomagnetism 83

3.3 Magnetic properties of rocks 87

3.4 The Earth’s magnetic field 89

3.5 Magnetic instruments 95

3.6 Magnetic surveying 100

3.7 Qualitative interpretation 103

3.8 Quantitative interpretation 107

3.9 Applications and case histories 123

4 Applied Seismology: Introduction and Principles 143

4.1 Introduction 143

4.2 Seismic waves 144

4.3 Raypath geometry in layered ground 149

4.4 Loss of seismic energy 152

4.5 Seismic energy sources 154

4.6 Detection and recording of seismic waves 169

5 Seismic Refraction Surveying 179

5.1 Introduction 179

5.2 General principles of refraction surveying 179

5.3 Geometry of refracted raypaths 182

5.4 Interpretational methods 186

5.5 Applications and case histories 193

5.6 Shear wave methods 208

6 Seismic Reflection Surveying 217

6.1 Introduction 217

6.2 Reflection surveys 217

6.3 Reflection data processing 228

6.4 Correlating seismic data with borehole logs and cones 246

6.5 Interpretation 250

6.6 Applications 257

7 Electrical Resistivity Methods 289

7.1 Introduction 289

7.2 Basic principles 289

7.3 Electrode configurations and geometric factors 293

7.4 Modes of deployment 301

7.5 Interpretation methods 311

7.6 ERT applications and case histories 326

7.7 Mise-`a-la-masse (MALM) method 336

7.8 Leak detection through artificial membranes 346

8 Spontaneous (Self) Potential Methods 349

8.1 Introduction 349

8.2 Occurrence of self-potentials 349

8.3 Origin of self-potentials 349

8.4 Measurement of self-potentials 353

8.5 Corrections to SP data 354

8.6 Interpretation of self-potential anomalies 354

8.7 Applications and case histories 357

8.8 Electrokinetic (EK) surveying 371

9 Induced Polarisation 373

9.3 Measurement of induced polarisation 376

9.4 Applications and case histories 384

10 Electromagnetic Methods: Introduction and Principles 403

10.1 Introduction 403

10.2 Principles of EM surveying 407

10.3 Airborne EM surveying 411

10.4 Seaborne EM surveying 418

10.5 Borehole EM surveying 426

11 Electromagnetic Methods: Systems and Applications 431

11.1 Introduction 431

11.2 Continuous-wave (CW) systems 431

11.3 Pulse-transient (TEM) or time-domain (TDEM) EM systems 467

12 Electromagnetic Methods: Systems and Applications II 495

12.1 Very-low-frequency (VLF) methods 495

12.2 The telluric method 502

12.3 The magnetotelluric (MT) method 505

12.4 Magnetic Resonance Sounding (MRS) 519

13 Introduction to Ground-Penetrating Radar 535

13.1 Introduction 535

13.2 Principles of operation 537

13.3 Propagation of radiowaves 539

13.4 Dielectric properties of earth materials 546

13.5 Modes of data acquisition 552

13.6 Data processing 554

13.7 Interpretation techniques 560

14 Ground-Penetrating Radar: Applications and Case Histories 565

14.1 Geological mapping 565

14.2 Hydrogeology and groundwater contamination 571

14.3 Glaciological applications 578

14.4 Engineering applications on manmade structures 587

14.5 Voids within manmade structures 599

14.6 Archaeological investigations 603

14.7 Forensic uses of GPR 607

14.8 Wide-aperture radar mapping and migration processing 607

14.9 Borehole radar 609

14.10 UXO and landmine detection 617

14.11 Animals 618

15 Radiometrics 625

15.1 Introduction 625

15.2 Natural radiation 625

15.3 Radioactivity of rocks 628

15.4 Radiation detectors 628

15.5 Data correction methods 633

15.6 Radiometric data presentation 635

15.7 Case histories 636

Appendix 645

References 649

Index 681