This research monograph discusses all the branches of geophysics based on natural electromagnetic fields and their associated subjects. Meant for postgraduate and research level courses, it includes research guidance and collection of magnetotelluric data in some parts of Eastern India and their qualitative and quantitative interpretation. Specific topics highlighted include (i) Electrotellurics, (ii) Magnetotellurics, (iii) Geomagnetic Depth Sounding and Magnetometer Array Studies, (iv) Audio Frequency Magnetotellurics and Magnetic Methods, (v) Marine Magnetotelluric and Marine Controlled Source Electromagnetic Methods, (vi) Electrical Conductivity of Rocks and Minerals and (vii) Mathematical Modelling and Some Topics on Inversion needed for Interpretation of Geoelectrical Data.

Autorentext
Kalyan Kumar Roy helds M.Sc and Ph.D from the Department of Geology and Geophysics , Indian Institute of Technology, Kharagpur, West Bengal, India. In 1966,he joined as a faculty member in the same department. In 1975 Dr. Roy was offered post doctorate fellowship of the National Research Council of Canada, by the Department of Environment , Ottawa, Canada for a period of one year. He returned from Canada and joined the same department as a faculty member. He retired as a Professor of Geophysics in the year 2002 after 36 years of service. He then served as an Emeritus Scientist in the Department of Geological Sciences, Jadavpur University, Kolkata from 2003 to 2009 and as an Adjunct Professor at IIT,Kharagpur from 2010 to 2011. He was a Guest Professor of the Department of Applied Geology, Dibrugarh University , Assam from 2013 to 2015. He joined as a Visiting Professor in the Department of Earth Sciences, Indian Institute of Engineering Science and Technology, Shibpur, Howrah, West Bengal, India in 2011 and continued upto 2019. He has published 77 papers, one single authorship book, one edited volume of multi authorship book and contributed in several multi aurhored books.
Dr.Roy was selected as a fellow of the National Academy of Science and fellows and life members of all the important Earth Science Societies of India. He is a life member of the Society of Petroleum Geophysicists based in Houston Texas, USA and Dehradun, Uttarakhand,I ndia. He attended many international conferences organized by I.U.G.G. (International Union of Geodesy and Geophysics),I.G.C.(International Geological Congress) and Electromagnetic workshops.

Zusammenfassung
This research monograph presents all the branches of geophysics based on natural electromagnetic fields and their associated subjects. Meant for postgraduate and research level courses, it includes research guidance and collection of magnetotelluric data in some parts of Eastern India and their qualitative and quantitative interpretation. Specific topics highlighted include (i) Electrotellurics, (ii) Magnetotellurics, (iii) Geomagnetic Depth Sounding and Magnetometer Array Studies, (iv) Audio Frequency Magnetotellurics and Magnetic Methods, (v) Marine Magnetotelluric and Marine Controlled Source Electromagnetic Methods, (vi) Electrical Conductivity of Rocks and Minerals and (vii) Mathematical Modelling and Some Topics on Inversion needed for Interpretation of Geoelectrical Data.

Inhalt
Chapter 1. General Introduction1.1 Introduction1.2 Preliminaries on Electromagnetic Waves and Their Application in Geophysical Investigation1.3 Geomagnetic Field1.3.1 Magnetic Field of Internal Origin1.3.1.1 Dipole Field of Internal Origin1.3.1.2 Nondipole Field of Internal Origin1.3.1.3 Inclination and Declination of the Magnetic Field1.3.2 Nondipole Time Varying Magnetic Field of External Origin1.4 Solar Radiation1.5 Solar Energy1.6 Sun Spot Cycle1.7 Solar Quiet Day (Sa) Variations1.8 L. Variations1.9 Equatorial Electrojet (EEJ) and Polar Electrojet (PEJ)1.10 Solar Flare Effects (SFE)1.11 Magnetic Storms and Substorms1.12 D, Dst, Ds Variations1.13 Bay Type Variations1.14 Interaction Between the Sun and the Earth1.15 Magnetosphere1.16 Cosmic Rays1.17 Van Allen Radiation Belt1.18 Ionosphere1.19 Ring Current1.20 Magnetotail1.21 Geomagnetic Field Variations1.22 Classifications and Causes of the Different Pulsations and Micropulsations1.22.1 Classification by Jacobs and Sinno (1960)1.22.2 Classification by Madam Troitskaya (1962)1.22.3 Classification by Benioff (1960)1.22.4 Classification by Tepley and Wentworth (1962)1.22.5 Classification by Vladimirov and Kleimenova (1962)1.23 High Frequency Natural Electromagnetic Signals, Sferics1.24 Earth's Natural Electromagnetic Fields as a Subject1.24.1 Electrotelluric Method (T)1.24.2 Magnetotelluric Methods (MT)1.24.3 Geomagnetic Depth Sounding (GDS)1.24.4 Magnetometer Array Studies (MA)1.24.5 Magnetovariational Sounding (MVS)1.24.6 Audiofrequency Magnetotelluric Method (AMT)
1.24.7 Sea Floor Magnetotelluric Method (SFMT)1.24.8 Marine Magnetotellurics (MMT)1.24.9 Audiofrequency Magnetic Method (AFMAG)1.25 Controlled Sources1.25.1 Controlled Source Audiofrequency Magnetotellurics (CSAMT)1.25.2 Controlled Source Marine Electromagnetics (CSEM)1.25.3 Long Offset Electromagnetic Transient (LOTEM)1.25.4 Radio Magnetotellurics (RMT)1.26 Coverage of This Book1.27 References
Chapter 2. Electrical Conduction Through Rocks2.1 Introduction2.2 Electrical Conductivity2.2.1 Expression of Electrical Conductivity for an Homogeneous and Isotropic Medium due to a Point Source of Current2.2.2 Specific Resistivity or Conductivity2.2.3 Ohm's Law2.3 Electrical Permittivity and Displacement Current2.3.1 Dielectric Constant2.3.2 Electric Displacement and Displacement Vector D2.3.3 Tensor Electrical Permittivity 2.4 Magnetic Induction and Magnetic Permeability2.4.1 Magnetic Induction2.4.2 Magnetic Permeability2.5 Principal Methods of Electrical Conduction2.5.1 Electronic Conduction (Conduction Through Metals)2.5.2 Conduction of Current Through Semiconductors2.5.3 Conduction of Current Through Solid Electrolytes2.5.4 Conduction of Current Through Electrical Displacement2.5.5 Electrolytic or Ionic Conduction2.6 Factors Which Control the Electrical Conductivity of the Earth2.6.1 Porosity of Rocks2.6.2 Conductivity of Pore Fluids2.6.3 Size and Shape of Pore Spaces2.6.4 Conductivity of Mineral Inclusions2.6.5 Size and Shape of Mineral Grains2.6.6 Temperature2.6.7 Frequency of Excitation Current2.6.8 Ductility and Degree of Partial Melt in Rocks2.6.9 Electrical Conductivity of Different Types of Roc...