Resistivity tomography (ERT) or resistivity imaging (ERI) is a geophysical technique that measures resistivity from the surface or through electrodes at one or more electrodes to image structures below the surface. If the pole is suspended in a well, the deep part can be investigated. It is closely related to medical tomography (resistance tomography) and is mathematically the same inverse problem. In contrast to the medical economic transformation, however, ERT is basically a direct current approach. A related geophysical method, biased (or spectrally biased), measures the transient response and aims to determine the characteristics of subsurface charging.
Below is the measurement results: