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MAGNETICS
The earth is the source of, and is consequently
enveloped in, a weak magnetic field which varies
in intensity with time and location. The presence
of ferrous metal disturbs this ambient magnetic
field in a mathematically
predictable manner, and measurement of this
ambient magnetic field can be useful in locating
and characterizing
buried metallic objects. Near-surface magnetic
objects, such as tanks, drums, and pipelines,
result in high vertical gradients in the local
magnetic field intensity. Measurement of the
vertical magnetic gradient, called magnetic
gradiometry, is particularly useful for locating
shallow metallic objects. The total magnetic field
is measured for deeper applications such as iron
ore deposits or groundwater basin studies. |
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