f Geological Interpretation of Multi-Electrode Resistivity Results in Geothermal Research

Recently, one of the most popular methods at geothermal researches is the resistivity method. In this method, multi-electrode measuring tools have started to use simultaneously with the development in the electronic and computer technologies. By the use of multi-electrode tools, rapid researches can be made in wide areas and more information can be obtained about subsurface. Geological and hydrogeological properties are both maintained by the parameters which were attained after some measurements. For a few years, the evolution of electronic components and computer processing have permitted to develop field resistivity equipment which includes a large number of electrodes located along a line at the same time, and which carries out an automatic switching of these electrodes for acquiring profiling data. The apparent resistivity pseudo sections measured with such a technique are processed by an inversion software which gives interpreted resistivity and depth values for the anomalies detected along the profile. The multi-electrode resistivity technique consists in using a multi-core cable with as many conductors (24, 48, 72, 96, ...) as electrodes plugged into the ground at a fixed spacing, every 5m for instance. In the resistivitymeter itself are located the relays which ensure the switching of those electrodes according to a sequence of readings predefined and stored in the internal memory of the equipment. The various combinations of transmitting (A,B) and receiving (M,N) pairs of electrodes construct the mixed sounding / profiling section, with a maximum investigation depth which mainly depends on the total length of the cable. In this study, applications are being examined geological interpretation of electrical resistivity imaging studies to geothermal fluid potential and specified geological site of faults are important elements for conceptual geothermal model at the investigation area.