Interpretation of Magnetic Anomalies in Salihli (Turkey) Geothermal Area Using 3-D Inversion and Edge Detection Techniques

Emre Timur, Coskun Sarı

There are numerous geophysical methods used to investigate geothermal areas. The major purpose of this magnetic survey is to locate the boudaries of active hydrothermal system in the South of Gediz Graben in Salihli (Manisa/Turkey). The presence of the hydrothermal system had already been inferred from surface evidence of hydrothermal activity and drillings. Firstly, it was necessary to convert the total field anomaly into a pseudo-gravity anomaly map. Then the geometric boundaries of the structures were determined by applying a MATLAB based software with 3 different edge detection algorithms. The exact location of the structures were obtained by using these boundary coordinates as initial geometric parameters in the inversion process. In addition to these methods, reduction to pole method was applied to the data to achieve more information about the location and shape of the possible reservoir. As a result, the edge detection methods were found to be successful in the field data sets for delineating the boundaries of the possible geothermal reservoir structure. The depth of the geothermal reservoir was determined as 2,4 km from 3-D inversion and 2,1 km from power spectrum method. The results of this study also suggest that the Salihli geothermal prospect extends further to the south of a resistivity boundary delineated from previous studies.