In contrast to the radial (vertical) component of gravity which varies by only roughly 0.5 percent over the eartha#39;s surface, the geomagnetic field ... This is diagramatically illustrated by the imaginary lines of magnetic force of the earth ( Figure 2a).
|Title||:||Geotechnical and Environmental Geophysics: Review and tutorial|
|Author||:||Stanley H. Ward|
|Publisher||:||Soc of Exploration Geophysicists - 1990|