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Indian Institute of Science Education and Research Berhampur

Earth and Environmental Sciences

EES 320 : Introduction to Geophysics (4)

Prerequisites:All 100 and 200 level EES, MTH, and PHY courses

Learning Objectives:

This course is a general introduction to the study of the physics of the solid Earth, including the dynamics of both the Earth's surface and its deep interior. Geophysics provides tools and methods which can image the subsurface through measurements which are mostly made remotely from the Earth’s surface. It describes the subsurface of the Earth in physical terms – density, electrical resistivity, magnetism, conductivity, and heat flow. Upon completion of this course the student will learn to appreciate the application of geophysics for understanding the physical conditions of the Earth’s multi-layered interior.

Course Contents:

Unit-1: An Introduction to Geophysical Methods
Introduction; The problem of geophysical expression, lateral or vertical variation of the Earth, geophysical surveys, signal processing, interpretation of the geophysical data, and application of different geophysical methods.

Unit-2: Gravity and the Earth
The nature and characteristics of the gravitational field of the Earth; The Earth’s size, shape and figure - geoid and spheroid; Potential field equations and derivation; Newton's gravitational law, Green’s theorem, Helmholtz equation, Laplace's and Poisson's Equations; Effect of rotation on Earth's shape; Gravity field of the Earth; International gravity formula; Reduction of gravity data; Gravimeters; Global gravity anomalies; Isostasy; Satellite geodesy, temporal variations, tidal friction.

Unit-3: Geomagnetism
History of Magnetism; Basic physics of magnetics; Magnetic field of the Earth; Rock magnetism, magnetic potential of the Earth in terms of spherical harmonic coefficients; Origin of magnetic field – internal and external origin; Temporal variations – secular and diurnal; Magnetic field strength; International Geomagnetic Reference Field (IGRF); Origin of dipole field; Dynamo theory.

Unit-4: Paleomagnetism
Introduction to paleomagnetism; Polar wandering; Euler pole and continental drift; Geomagnetic polarity; Seafloor spreading and continental drift; Filtering (magnetic) data; Modelling and interpretation of magnetic anomalies.

Unit-5: Geoelectromagnetism
Basic electrical and electromagnetic concepts; Principles of magnetotelluric (MT) method; Sources of MT, dead band; Principle of induction coil and fluxgate magnetometers, MT Data Acquisition, MT parameters viz., impedance, skew, ellipticity, tipper; MT processing, modelling and interpretation; Study of the interior of the Earth from magnetotelluric studies.

Unit-6: Seismology and the Internal Structure of the Earth
Elastic theory; Snell's law; Seismic waves and the ray parameter; Surface waves, body waves, free oscillations; Global seismicity; Magnitude and intensity; Seismograph, seismogram, seismic phases; Earthquake mechanisms; Travel-time curves, inversion, velocity structures; Velocity and internal structure of the Earth; Surface wave dispersion and free oscillations; Seismic tomography.

Unit-7: Geothermics
Mechanism of heat transport in the Earth; Head conduction equation, heat flow density; Heat flow measurements; Temperature distribution (geotherm); Factors contribution to heat flow; Oceanic and continental heat flow; Global heat flow maps; Thermal structure of mid-ocean ridges and trenches; Mantle convection – hotspots and mantle plumes; Heat flow measurements and simple estimates of thermal history from diffusivity values, Solutions of diffusion equation. Outline of Geophysical Exploration

Suggested Readings :

  1. Musset, A. E., and Khan, M. A., 2000, An Introduction to Geological Geophysics, Cambridge University Press.
  2. Lowrie, W., 2011, Fundamentals of Geophysics (2nd Edition), Cambridge University Press.
  3. Fowler, C. M. R., 2004, The Solid Earth – An Introduction to Global Geophysics (2nd Edition),Cambridge University Press.
  4. Dobrin, M. B., and Savit, Carl, H., 1988, Introduction to Geophysical Prospecting (4th Edition), McGraw Hill International.
  5. Telford, W. M., Geldart, L. P., Sheriff, R. E., 1990, Applied Geophysics (2nd Edition), Cambridge University Press.

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