Investigation of the influence of faults on geoelectric strikes and dimensionality analysis of MT data in the Sabalan geothermal area

The Sabalan geothermal in northwestern Iran is the most well-known geothermal in the country. Due to the Sabalan caldera's structures and dozens of younger faults, the area consists of highly fractured rocks. Besides, processing the aeromagnetic data in the area revealed some other hidden faults. To investigate the effect of the faults on the geothermal system, we conducted a dimensionality analysis based on magnetotelluric impedance and phase tensors from two magnetotelluric datasets. The datasets were surveyed at different times, one in the dry season of June 1998 and the other in the wet season of November 2007. The dimensionality behavior obtained from the datasets differs significantly. We realized that the discrepancy was due to the time of conducting the magnetotelluric survey. For instance, the polar diagrams computed from the dry season data showed a better correlation with fault strikes in some of the frequencies where the wet season data polar diagrams were less sensitive to the fault orientations. Besides, the strike of a hidden fault extracted from aeromagnetic data was apt to the extension of Zxy's polar diagram. Furthermore, the dimensionality analysis and skew angle in dry season data demonstrate a 2D to 3D media, whereas the wet season data showed a 1D to 2D earth. We deduced that faults have a more significant role in providing resistivity contrast in dry seasons and hence, a better illustration for the geoelectric strike.