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Services: VLF Methods
Applications
- Find water-bearing faults & fracture zones
- Locate discontinuities
- Identify conductive bodies
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A very low frequency (VLF) investigation is well suited to the location of geologic faults (and approximating their attitudes), some types of geologic contacts, and buried conductive bodies including water-bearing faults. The VLF-EM frequency method is a passive system as it utilizes a fixed position transmitter broadcasting a frequency between 15 and 30Kz.
In a VLF investigation, the magnetic field components of the transmitted signal are measured, although the electrical field components can also be measured as required. Measurements of the electrical components are referred to as a VLF resistivity investigation (VLF-R). The highly portable VLF receiver is easily carried and operated by one field person. This method can delineate contrasts in conductivity at depth and is used in the search for contacts, faults, mineralized bodies, overburden, fractures, and voids, and for a variety of other purposes, including the location of utility lines and siting of water wells.
Targets are of two primary types; 1) linear trends of considerable length that are more than 30 degrees from the horizontal ; and 2) broader zones of lateral changes in conductivity related to such features as a plumes or alteration zones.
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