neljäelektrodimenetelmää

The four-electrode method, known in Finnish as neljäelektrodimenetelmä, is a fundamental technique used in electrical resistivity surveys and geophysics. It is employed to measure the electrical resistivity of the subsurface by injecting current into the ground and measuring the resulting potential difference. This method uses four electrodes, typically arranged in a straight line. Two outer electrodes inject a direct or low-frequency alternating current into the earth, while two inner electrodes measure the potential difference between them.

The arrangement of the electrodes is crucial for the accuracy of the measurements. Common configurations include the Wenner array, Schlumberger array, and dipole-dipole array, each with its own advantages and applications depending on the desired depth of investigation and the geological context. By varying the spacing between the electrodes, geophysicists can probe different depths of the subsurface. The measured apparent resistivity is then interpreted to infer the geological structures and properties, such as the presence of water-bearing zones, mineral deposits, or contaminants. The four-electrode method is widely used in groundwater exploration, mineral prospecting, archaeological surveys, and environmental studies due to its relatively simple setup and effective data acquisition capabilities.