Resistivity

Applications Include
Fault problems
Water table determinations
Contamination plumes
Lithology
Tunnel/Cavern Mapping
Landfill delineation

Resistivity contrast occurs in the subsurface between, for example, dry and water bearing sediments, differing rock lithologies and differing weathering histories.
Using an electrical apparatus with two current electrodes, one a source and the other a sink, and two potential electrodes a depth electrical profile can be
measured when the electrode spacing is progressively expanded. The field between the electrodes is distributed only near the surface when the electrodes spacing is close but the electrical flux flows deeper when the electrodes are further apart. The flux will crowd into the more conductive layers and will rarefy in the more resistive layers. The potential at the surface will reflect these path differences and will provide a data set from which an electrical profile model of the subsurface can be calculated.

The STING device operates in the same manner as outlined above but the STING system uses 56 electrodes instead of 4 and it is computer controlled. Any combination of four electrodes can be selected at a time and then measurements can be made with it. The selection process can be systematic and automated so that an expanded spread and depth profile can be determined in all 56 electrode positions. Thus an electrical structure section can be calculated and displayed.

 

STING Resistivity Data Profile

 

 
 
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