After completing the course the student is expected to be able to :
derive the quasistatic differential equations governing electromagnetic induction in the Earth starting from Maxwell's equations.
Explain how the Earth can be excited galvanically and inductively.
Derive expressions for surface impedance for plane waves over a stratified Earth.
Describe and apply the fundamental properties of the impedance tensor and other transfer functions for plane waves over an arbitrary Earth.
Explain the principles of how numerical models can be used to solve forward problems in 2- and 3-D.
Explain how model sensistivities can be calculated using the reciprocity theorem.
Explain how resolution of inverse models may depend on structure and data coverage.
Derive least squares estimates of transfer functions from experimental data and explain how bias and random errors can be calculated.
Explain static shifts and how they can be compensated for.
Be acquainted with the most popular controlled source techniques in frequency and time domain.
Account for important applications of EM techniques in applied and global geophysics.
Make recommendations as what technique is best suited for solving a given EM problem with respect to depth penetration and resolution.
Maxwell’s equations in the quasistationary approximation. Source representations in the wavenumber domain. The Earth as a filter. Surface transfer functions. Analytic solutions in 1D. Properties of 1D transfer functions. Numerical methods in 2D and 3D. Solving forward problems with finite difference and integral equations. The reciprocity theorem and applications to calculate model sensitivities. Solving inverse problems in 1D, 2D and 3D. Resolution and uncertainties. Estimation of transfer functions and uncertainties from experimental time series. Effects of near surface inhomogeneities on electric and magnetic fields. Frequency and time domain responses for dipolar sources over a 1D Earth. Applications in applied and environmental geophysics and crustal and upper mantle studies.
Lectures, home work assignments, problem solution and computer exercises.
Written examination (8 credits) and compulsory parts (2 credits).
week 25, 2013
Corbett, John D.;
Nabighian, M. N.
Electromagnetic methods in applied geophysics. : Vol. 1 Theory
Society of Exploration Geophysicists,