Identification of structural geology at the Tangkuban Parahu geothermal area, West Java based on remote sensing and gravity data

Abstract

Tangkuban Parahu is located in the north of Bandung, the capital province of West Java. Several hydrothermal manifestations, such as hot and warm springs with a temperature of 29°C-80°C, indicate that the Tangkuban Parahu has potential as a geothermal prospect. In such a case, understanding the surface and subsurface geological structures in the prospect area is needed as the first step in geothermal exploration. This study identifies geological structures based on remote sensing and gravity datasets. Structural lineaments were extracted manually using GIS software to produce fault, and fracture density (FFD) maps from the DEMNAS dataset along with IFSAR and ALOS PALSAR images. Lineament extraction was performed at eight different sun azimuth angles (hillshade) to reduce non-meaningful lines that may appear. The FFD maps show that most of the surface manifestation correlates with the high FFD zones. Gravity method is one of the first steps in geothermal exploration to provide an overview of the distribution of rocks and subsurface geological structures. Gravity data were analyzed using the parasnis method to reflect the average of rock density. The derivative technique for gravity method is common to be applied in order to delineate subsurface geological structures [1]. In this research, we used First Horizontal Derivative (FHD) and Second Vertical Derivative (SVD) to determine the presence and the type of major fault. The results of this research indicate that most of the high FFD zones are located in the peak maximum of FHD, which has SVD=0. Nevertheless, there are 3 locations of the high FFD zone that have no peak maximum FFD. Integration of this analysis mostly shows that the existence of geological structures is related to surface hydrothermal manifestations.