Advances in Biology & Earth Sciences

Indonesia is an archipelago surrounded by volcanoes, thus possessing abundant geothermal resources as a renewable energy prospect. One such manifestation is found in the Karangrejo-Tinatar area in Pacitan. This study focuses on identifying geological structures and the geothermal system by analyzing 3D density and magnetic susceptibility models, generated from the inversion of gravity and magnetic anomalies around Karangrejo-Tinatar. Gravity anomalies provide insights into geological structures, while magnetic anomalies determine the demagnetization zones associated with heat flow. The 3D density model indicates the presence of four local faults in the study area, which are suspected as hot fluids channels to reach the surface and form geothermal manifestations. A low magnetic anomaly was detected in the southern of the study area and interpreted as the geothermal reservoir of the Karangrejo-Tinatar system. The 3D susceptibility models shows a demagnetization zone with a very low magnetic susceptibility value in the studied area, which indicates the presence of the geothermal reservoir, representing the volcanic rock formation. The integration of the 3D inversion models of gravity and magnetics shows a discrepancy, where a high-density value is coupled with low magnetic susceptibility. This phenomenon indicates the movement of geothermal fluid through a fractured caprock.