Foreword ........................................................ v
Preface ....................................................... vii
Abbreviations .................................................. xv
1 The Historical Development of (Geo)Magnetism ................. 1
1.1 Global Scene ............................................ 1
1.2 Fundamental Similarity between Electricity and
Magnetism .............................................. 10
1.3 Historical Perspective: National Scene against Global
Backdrop ............................................... 14
1.4 Geomagnetic Field Elements and Their Measurements ...... 16
2 Internal Magnetic Field ..................................... 24
2.1 Interior of the Earth and Physical Properties .......... 25
2.2 Earth Structure and Its Major Divisions ................ 31
2.3 Magnetism in Matter and Magnetic Properties ............ 37
2.4 Curie and Neel Temperature ............................. 42
2.5 Rock Forming Magnetic Minerals and Rock Magnetism ...... 43
2.6 Hysteresis Loop ........................................ 58
2.7 Magnetic Materials, Domain States and Grain Sizes ...... 59
2.8 Genesis of Earth's Magnetic Field and Its Dynamo
Effect ................................................. 66
2.9 Wegener and Continental Drift .......................... 69
2.10 Palaeomagnetism: An Indirect Measurement of Past
Geomagnetic Field ...................................... 71
2.11 Mechanism of Magnetic Banding .......................... 76
2.12 Plate Tectonics and Seismotectonics .................... 79
3 Magnetic Field that Extends into Space ...................... 87
3.1 Structure of the Earth's Atmosphere: Traditional
View ................................................... 89
3.2 Structure of the Sun: Association of Sunspots with
Terrestrial Phenomena .................................. 94
3.3 Structure of Magnetosphere ............................ 105
3.4 Sources of Electric Fields ............................ 107
3.5 Radio Waves: Scintillation ............................ 110
4 Technique of Magnetic Measurements ......................... 115
4.1 Magnetometery for Geomagnetic Observatories ........... 117
4.2 Magnetic Survey Instruments: Fluxgate and Induction
Magnetometers ......................................... 125
4.3 Laboratory Magnetic Instruments ....................... 131
5 Magnetic Observatories and Data Analysis ................... 142
5.1 Measurement and Data .................................. 146
5.2 Geomagnetism and Secular Variation .................... 150
5.3 Causes of Geomagnetic Field Variation: External
Origin ................................................ 154
5.4 Equatorial Enhancement and Geomagnetic Field
Variations ............................................ 159
5.5 Geomagnetic Storms and the Magnetosphere .............. 167
6 Solid Earth Geomagnetism ................................... 174
6.1 Geopotential Field Anomaly Studies .................... 177
6.2 Satellite Measurements of Earth's Gravity Field ....... 179
6.3 Satellite Measurements of the Earth's Magnetic
Field ................................................. 187
6.4 Air-borne Magnetic Surveys ............................ 199
6.5 National Ground Magnetic Surveys ...................... 208
6.6 Ground Magnetic Surveys ............................... 210
6.7 Electromagnetic (EM) Induction Methods ................ 222
6.8 Basic Method of EM Induction .......................... 223
6.9 Geomagnetic Depth Sounding (GDS) ...................... 226
6.10 Methodology, Objectives of GDS Technique .............. 226
6.11 Acquisition, Analysis and Presentation of GDS Data .... 227
6.12 Data Processing Techniques ............................ 228
6.13 GDS Field Surveys ..................................... 230
6.14 Magnetic Variation Mapping Examples ................... 231
6.15 Ocean Bottom Magnetometer Studies ..................... 235
6.16 OBM Field Examples .................................... 235
6.17 Magnetotelluric Surveys ............................... 236
6.18 Methodology, Data Acquisition and Time Series
Processing ............................................ 237
6.19 Principle ofMT Method and Its Utility ................. 241
6.20 Applications of MT in Geophysical Prospecting ......... 242
6.21 Earthquakes: Causatives and Measurements .............. 249
6.22 Major Earthquakes of the World and India .............. 252
6.23 Himalayan Tectonics and Its Effect on Peninsula ....... 254
6.24 Seismic Zonation Maps and Seimic Hazards .............. 259
6.25 Geophysical Studies in Seismically Active Regions ..... 261
6.26 Co-Seismic Investigations—Magnetic and Electrical
Rock Properties ....................................... 264
6.27 Predicting Earthquakes ................................ 265
6.28 Earthquake Precursory Changes ......................... 266
6.29 Earthquake Precursory Case Histories .................. 268
6.30 Palaeosiesmology: Quasi-Empirical Earthquake
Prediction Technique .................................. 274
6.31 GPS Measurements and Geodynamics ...................... 277
6.32 Observational Procedure ............................... 279
6.33 Methodology, Data Acquisition and Analysis ............ 280
6.34 GPS: Repeat Campaigns, Permanent Sites and Case
Studies ............................................... 282
7 Experimental Geomagnetism .................................. 291
7.1 Palaeomagnetism and Geomagnetic Field in Geological
Past .................................................. 292
7.2 Palaeolatitude, Pole Position, Apparent Polar Wander
Path .................................................. 304
7.3 Magnetochronology ..................................... 309
7.4 Implications of Palaeomagnetic Results ................ 316
7.5 Environmental Geomagnetism ............................ 321
7.6 Environmental Geomagnetism vs. Palaeomagnetism ........ 322
7.7 Environmental Magnetism: Objectives and Evolution ..... 323
7.8 Primary Magnetic Measurements—Magnetic Properties ..... 334
7.9 Secondary Magnetic Parameters: Interparametric
Ratios ................................................ 348
7.10 Magnetic Studies, Complex Issues ...................... 351
7.11 Environmental Magnetism—Its Application to the
Indian Depositional Settings .......................... 354
7.12 Magnetic Susceptibility and Depositional
Environments .......................................... 356
7.13 Magnetomineralogical S-ratio and Palaeoclimate in
Sediments ............................................. 373
7.14 Future Studies ........................................ 376
8 Upper Atmosphere Studies ................................... 387
8.1 Space Weather Effects ................................. 398
8.2 Ionospheric Electrodynamics: Short Period
Fluctuations .......................................... 406
8.3 Equatorial-Latitude Electrodynamical Coupling and
Atmospheric Structure ................................. 414
8.4 Antarctic Magnetic Data ............................... 419
9 Usefulness of Geomagnetic Research ......................... 423
9.1 Observatories and Data Analysis ....................... 424
9.2 Solid Earth Geomagnetism .............................. 427
9.3 Upper Atmospheric Studies ............................. 437
10 Perspective ................................................ 449
10.1 Solid Earth Geomagnetism .............................. 452
10.2 Current Trends/Geomagnetism ........................... 458
Select Bibliography ........................................... 460
Index ......................................................... 477
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