Wenner array
Definition
A four-electrode resistivity configuration where all four electrodes are equally spaced. Depth of investigation is approximately equal to the electrode spacing. Provides good sensitivity but requires four electrodes to be moved between measurements, making it slower than twin-electrode.
- Configuration
- Four equally spaced electrodes; outer two inject current, inner two measure voltage
- Depth of investigation
- Approximately equal to electrode spacing distance
- Sensitivity
- Good sensitivity to horizontal layering; used for depth sounding in forensic surveys
- Trade-off
- Good sensitivity but slower than twin-electrode methods due to full electrode repositioning between measurements
Common questions
How deep can a Wenner array detect underground features?+
The depth of investigation is approximately equal to the electrode spacing distance. For example, if electrodes are spaced 1 meter apart, the array can investigate to roughly 1 meter depth. This relationship makes it easy to adjust survey depth by changing electrode spacing.
What makes the Wenner array useful in forensic surveys?+
The Wenner array is sensitive to horizontal layering and commonly used for depth sounding in forensic ERT (electrical resistivity tomography) surveys. It provides good sensitivity to changes in soil properties but does require moving all four electrodes between measurements.
Why would forensic teams choose a Wenner array over other resistivity methods?+
The Wenner array offers good sensitivity and a predictable depth of investigation proportional to electrode spacing. However, it is slower than twin-electrode methods because all four electrodes must be repositioned for each measurement. The choice depends on whether depth accuracy and sensitivity outweigh speed requirements for the investigation.
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Explained in these topics
- Magnetometry and Earth ResistanceA four-electrode resistivity configuration where all four electrodes are equally spaced. Depth of investigation is approximately equal to the electrode spacing...
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