DC Resistivity (M-3)
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Q: How does it work?
A: An electrical current is impressed into the ground through two electrodes. Voltages on the surface are
measured revealing the direction and amount of current flow in the subsurface. These data are interpreted
in terms of the resistivity (bulk resistance to current flow) of the earth materials.
- Q: What are the
requirements?
A: A powerful source:
Special purpose transmitters put up to 3 kilowatts of power into the ground
A low-noise receiver:
Multichannel voltmeters capable of resolving a few microvolts
Low interference from:
Grounded fences
Operating power plants or power lines
Shockable people or animals
Surface Access:
electrodes driven or drilled into ground
Ground truth:
Well logs
Drill holes
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Q: What are the pitfalls?
Ambiguity:
A: Interpretation is one-dimensional (electric drilling) or two-dimensional (electric trenching).
Conductivity-thickness equivalence.
Current channeling in conductive environments
- Q: What
logistics are needed?
A: Crew size usually 2 or 3 people. Portable if source can be carried.
- Q: What
are the deliverables?
A: Plan maps, data presentations, inverse models, forward calculations of the same
model or cross-section, and a narrative description of the work done.
- More detailed information.