Electrical tomography profiles (ERT) are currently the most widely used in electrical prospecting. They measure the variations in the physical parameter of the electrical resistivity of subsoil materials and provide a depth image that describes the thickness of the layers with different electrical behavior. The resistivity sections obtained are correlated with the geological or geophysical information of the area and allow detailed information on the earth's subsoil to be obtained.

Methodology

Traditional configurations of electrical tomography profiles (ERT) use four electrodes. An electric current is injected into the ground through two of the electrodes and the potential difference is measured with the other two. From the measured current and potential difference values, the distribution of the electrical resistivity of the subsoil can be obtained, a physical property of the material that measures the difficulty that the electric current presents in crossing it.

Diagram of an electrical tomography device with the corresponding distribution of current and potential lines in the subsoil.

The ERT technique uses the apparent resistivity values ​​measured on the surface to generate images called pseudosections, which are necessary to solve the inverse problem and obtain a model of electrical resistivity distribution..

Model of electrical resistivity of the subsoil in an electrical tomography.

Applications

• Definition of contacts between subsurface materials (boundaries).
• Detection of the rocky substrate.
• Detection of the water table.
• Detection of cavities or old water mines.
• Detection of paleochannels.
• Identification of fractured areas and discontinuities.
• Location of areas contaminated with leachates.
• Definition of areas affected by saline intrusion.