IDENTIFICATION OF SUBSURFACE STRUCTURE OF AREA “X” AS GEOTHERMAL POTENTIAL AREA BASED ON MAGNETIC DATA MODELING

• Main Author: Nathanael, Mariano
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/53224
• Institution: Institut Teknologi Bandung

One of the renewable energy sources in Indonesia is geothermal energy. The potential of this geothermal energy source is very large, reaching 40% of the world's geothermal potential which is spread over 299 locations throughout Indonesia (Sugiharta et al., 2016:3). One of the geophysical methods that can be used in search for geothermal potential areas is the magnetic method. This method is carried out based on the measurement of geomagnetic anomalies caused by differences in the magnetic susceptibility contrast of the surveyed areas (Broto and Putranto, 2011). Through magnetic data processing using a forward modeling approach, an estimate of the geological structure below the surface of area “X” can be obtained. This research uses Surfer 16 and Magpick software to perform magnetic data transformations in the form of upward continuation transformations and reduction to pole transformations. The resulting contour map is sliced into 3 intersecting slices and data for each slice is processed with a forward modeling approach using Mag2dc software which uses trial and error methods. The depth of modeling is 1000 meters and the modeling error for the three slices A-B, A-C, and A-D are respectively 3.82%, 5.06% and 2.89%. Results analysis of the modeling of the three slices are correspond to one another. Several layers of rock were found, the surface layer is thought to be dolomite sedimentary rock (susceptibility 0.001 in SI units), then at the bottom it is thought to be limestone (susceptibility 3,000 in SI units), which can be cap rock from geothermal sources as well as value rocks negative susceptibility (-0.01 SI to -1.494 in SI units), rocks that are thought to be rocks that have changed so that there is a decrease in the value of magnetic rock susceptibility. This indicates the presence of hot fluid flow from geothermal sources that are below the surface or it can also indicate the geothermal source area itself. In slice A-B, a fault area is also found, which indicates the fault is caused by geothermal pressure below the surface of area “X”.