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Existing Potential Method (USA)
When using specifically designed sensors the earth’s self-potential of direct currents can be
measured. The sensors become very useful when using a single forward motion just above,
without contacting, the earth. With this rather simple technique, the geophysicist can trace
zones of mineralization, having a strong signal, or tunnels having a weak signal. By receiving a
combination of AC/DC and frequency to map potentials, we can map fields of interest. These
rapid changing signals are amplified and analyzed by the software. The XL16 IMAGER allows
for the rapid collection and interpretation of large quantities of data, making it a cost effective
technique. EM equipment measures the background of the emitted signals from the earth; it
then detects any differences that are present. Differences can be caused by anything in the
subsurface that has disturbed the earth (like a void, metal objects, fault, tunnels, etc…). Other
available geophysical techniques that are sensitive to the presence of both ferrous and non-
ferrous metal objects include metal detectors, pulse induction, resistivity, ground penetrating
radar, etc…
What EM Measures
EM measures the apparent electromagnetic field of the ground, including effects of the soil,
bedrock fractures, contaminants, metal objects, and ground water. Variations in the
electromagnetic field may indicate changes in composition, layer thickness, or moisture content.
The presence of buried metal such as drums, and/or other objects create a large variation. The
UNDERGROUND SURVEYOR is specifically designed to detect subsurface anomalies by
receiving varying signals from the ground.
Magnetic Surveying
Magnetic surveying is ideal for both reconnaissance and focused surveys. It is expedient and
cost effective, covers more ground in less time, and requires a minimum of field support. The
portability of the instruments makes magnetic surveying well suited to sites with topographic
variations.
What Magnetic Measures
Magnetic surveys measure the earth's magnetic field and the Milligass level very accurately.
Buried ferrous materials, and in some cases, changes in bedrock lithology, produce disturbances
in the local magnetic field that can be readily detected by magnetic surveys. The
UNDERGROUND SURVEYOR instrument is one such device that takes measurements in
order to find anomalies that lie beneath the surface. Instruments like the “Discriminator”, uses
“Pulse Induction” to measure conductivity and in combination with a Magnetometer to
discriminate ferrous and to see non-ferrous objects
.
Summary of Contents for XL16 IMAGER
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