APPLICATION OF GRAVITY BOUGUER METHOD AND GRAVITY GRADIENT VERTICAL METHOD AT BANDUNG BASIN

• Main Author: Nugraha, Purwaditya
• Format: Theses
• Language: Indonesia
• Subjects: Teknik (Rekayasa, enjinering dan kegiatan berkaitan)
• Online Access: https://digilib.itb.ac.id/gdl/view/69625
• Institution: Institut Teknologi Bandung

Bandung is one of many cities in Indonesia that has a subsidence phenomenon which is very massive exactly located at the Bandung Basin area. Subsidence caused by the compaction phenomenon effect of emptiness material at the aquifer zone which excessive groundwater extraction has been carried out. Gravity method in this research used to identify the presence of the compaction zone beneath shallow subsurface and to delineate the geological structure of the subsurface. The residual Bouguer gravity method and gravity gradient vertical method is a geophysical method that is sensitive to differences of density in the subsurface but has high ambiguity in defining differences of that density in the vertical and horizontal direction. Application of residual Bouguer gravity method able to delineate the structure beneath the subsurface but has weakness to determine the shallow source anomaly, in this case, is compaction zone, on the other hand, gravity gradient vertical method able to determine shallow source anomaly but disable to delineate the structure like residual Bouguer gravity method. The combined application of residual Bouguer gravity method and the gravity gradient vertical method is expected to minimize that ambiguity and that lack both of that method. The application of this method in the Bandung Basin area shows that obtained two different in the compaction zone. The first compaction zone is at depth 40 meters with a thickness of 130 meters and has a density contrast 0.2 g/cc, where related with the geological structure in this form is a fault and anticline, then the second compaction zone is at depth 170 meters with a thickness of 100 meters and has a density contrast 0.1 g/cc, where related with the presence of basin structure.