Electromagnetic Methods

In this section we will study electromagnetic (EM) methods. In applied geophysics, the term is usually used to refer to methods that use a low frequency time-varying magnetic field as a source to excite electrical currents in the ground through the principle of electromagnetic induction. These methods are sensitive to the electrical conductivity of the subsurface. The GPR, DC resistivity and induced polarization methods are also governed by the laws of electromagnetism but excite the earth differently enough that they are classified separately.

Contents:

• Introduction
• Conductivity
• Basic Principles
• Survey
• Frequency Domain Data
• Processing
• Interpretation
• Applet