GPGN 303

Introduction to gravity & magnetic methods


Course Description:

This two-part course covers the basics of gravity and magnetic exploration methods. In the first part, we begin with Newton's law of gravitational force and study the variations in earth's gravity field and move on to the small-scale perturbations that are the signal of gravity exploration methods. This leads to the study of methods and instruments for measuring these variations and the associated field procedures. Subsequently, the correction and processing of the observed data will be discussed. This section concludes with the basic techniques for interpreting gravity data, which include the calculation of source parameters for simple anomalies. The second part of the course studies the magnetic methods of exploration. We begin with the fundamentals of magnetic field and study the earth's magnetic field and its variations. Aspects of instrumentation, survey procedure, data reduction, and interpretation will be studied. With the basic understanding of both gravity and magnetic methods, we examine the mathematical connection between the two methods, and study the integrated interpretation.

Gravity methods section:
  • Theory of gravitational field: gravitational force, Newton's law, gravity potential and Poisson's equation
  • Earth's gravitational field: its global variations and various components for describing the field
  • Principles of gravimeters
  • Survey design and field procedures
  • Gravity data reduction
  • Processing techniques for gravity data
  • Numerical modeling of gravity data
  • Interpretation and inversion of gravity data
Magnetic methods section:
  • Theory of magnetic field: magnetic field produced by a loop current and its dipolar approximation
  • Sources of magnetic field in exploration geophysics: magnetic susceptibility and magnetization
  • Earth's magnetic field: basic parameters of the field and its spatial and temporal variations
  • Principles of magnetometers
  • Data reduction and processing
  • Poisson's relation between gravity and magnetic fields
  • Numerical modeling of magnetic data
  • Interpretation and inversion of magnetic data: simple parameter estimation and examples of generalized inversion

Credit Hours: 4

Instructor: