Identification of Subsurface Structures in Geothermal Potential Areas Using Gravity and Magnetic Method: Case Study Ciseeng, West Java

Abstract

The Ciseeng geothermal area is a geothermal potential area in Bogor Regency, tertiary sedimentary rocks dominate West Java with surface manifestations such as hot springs and travertine deposits. Gravity and magnetic methods have been used to do study in this field. 79 gravity data and 191 magnetic data are spread out over a distance of 50 meters, with a measurement area of 3 km x 2 km. In the research area, complete Bouguer Anomaly values ranged from 56.1 mGal to 59.3 mGal. The total magnetic intensity in the research area was measured to be between -129.6 and 661.7 nanotesla. The upflow zone can be estimated by identifying structures in potential geothermal areas. A derivative analysis was applied as the method (First Horizontal Derivative and Second Vertical Derivative). This method determines where the geological structure is on track's cross-section. The forward modeling approach is used to estimate the density distribution of the subsurface model. The FHD and SVD analyses revealed that a reverse fault existed at L-3, whereas a strike-slip fault existed at L-5 and L-9. The rocks that make up the research area are alluvium, breccia, and limestone, according to the results of forward modeling of a 2D cross-section in a North-South direction. With an inaccuracy value of 9.584% for magnetic data and 0.032% for gravity data, a reverse fault was discovered around Peyek Mount in a northwest-southeast direction.