Geoelectrics

Geoelectrics is a geophysical method for a non-destructive exploration of the subsurface by measuring electrical potentials at the surface. Geo5 prefers the application of a multi electrode instrument for such measurements. For the measurement processes with multi electrode instruments, electrodes are arranged in equidistance along a profile on the surface. Then a current is applied to the subsurface using a defined pair of electrodes. Another pair of electrodes measures the difference of potential of the generated electrical field. From this difference the apparent electrical resistivity can be determined. This procedure is repeated with varying source and receiver electrode pairs.

The depth of penetration is strongly depending on the profile length, the used electrode configuration, and subsurface properties. A benchmark for depth of investigation is 15 - 25 % of the active profile length. The resolution of the final resistivity image is defined by the electrode distance and the electrode configuration. The electrode configuration also affects the sensitivity of the measurement to noise.

The result of geoelectrical survey is a vertical profile with a distribution of the specific electrical resistivity. Based on the resistivity it is possible to determine geological structures and lithology of the subsurface. Typical fields of application of this method are groundwater and mineral exploration as well as geotechnical surveys.