Electrical probing depth of ERT method

•  Exploration depth depends on the maximum length measurement arrangement, rather than depending on the length of the survey line. Scroll measure does not increase the depth of exploration.

•  In the number of electrodes and electrode spacing unchanged, diode array maximum depth exploration.

•  In general, any exploration depth of a four-pole arrangement is about 15% to 20% of the maximum length of the arrangement, but the field should be more conservative design, the depth should be 10% to 15% of the maximum length of the study of the arrangement.

•  Depth exploration of high-density electrical ground depends mainly on medium depth Edwards (1977) definition.

•  The actual depth exploration of underground resistivity distribution of relevant, good guide will greatly reduce overburden depths.

•  Exploration depth and the depth of the probe object associated with the ratio of diameter, the limit of this ratio is about 5.0


Order Median Depth
Wenner (AMNB) 17.3%of AB or 52% of a spacing
Schlumberger 19.1% of AB
Gradient 19.1% of AB
Non-conventional 19.1% of the largest electrode span
Pole-pole(A-M) 60% of AM
Dipole-Dipole (AB-MN) 14%~25% of the largest electrode span
Pole-Dipole (A-MN) 50%~60% of MN separation depending on