Interpretation of Tangkuban Perahu geophysical data (West Java - Indonesia)

Abstract

The Tangkuban perahu geothermal field is located in West Java, Indonesia, about 20 kilometres to the North of Bandung. Geophysical surveys of Tangkuban perahu, particularly using resistivity traversing and VES with schlumberger and Magnetotelluric arrays were made to evaluate the electrical resistivity distribution within the geothermal field. Low concealed resistivity anomalies are encountered in both the Kancah and Ciater area. The interpretation of the magnetotelluric soundings and VES curves by computer modelling indicates that deep outflow zones have a resistivity about 1 to 6 Ohm-me The outflows are overlain by a high resistivity layer of about 15-65 Ohm-me The low resistive zone, laterally, is confined by resistivity layer of about 14-42 Ohm-me Gravity anomalies over Tangkuban perahu are associated with Caldera structure infilled with less dense Pyroclastics. No detailed interpretation of the anomaly can be given since a major reduction error in the data was detected at the final stage of the project. A positive self potential anomaly observed in this area can be interpreted in terms of upflowing and outflowing mineralized fluids from the deep Tangkuban perahu system.