2.5 D SUBSURFACE STRUCTURE MODELLING OF LEMBANG FAULT AREA USING GRAVITY METHOD

• Main Author: Manik, Josaphat
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/44009
• Institution: Institut Teknologi Bandung

Bandung is a basin surrounded by a series of volcanoes that developed in the era of middleend quaternary and has a fault with a length of about 22 km in the West-East direction called the Lembang fault. This fault is located about 10 km north of Bandung City. This makes the geology of Bandung quite unique so that a method is needed to describe the structure under the surface of Bandung.One method that is quite good at describing subsurface structures is the gravity method. Gravity method is a passive geophysical method that measures the difference in the Earth's gravitational field in an area. In describing the subsurface, the gravity method utilizes rock density contrast. The subsurface model is made from a complete Bouguer anomaly print map Bandung, then digitized to obtain a complete digital Bouguer anomaly map. Furthermore, on the digital anomaly map, the separation of regional and residual anomalies is done using the moving average method. From the separation of the anomaly, a 2.5D modeling was carried out using background density of 2.67 g / cc. The modeling results show that Tangkuban Parahu has basaltic magma chamber at 870 meters, Lembang fault is a normal fault and the subsurface structure of Bandung consists of a layer of limestone which is the formation of Cilanang, a layer of breccia and a mixture of unclear old volcanic products, pumice tuff layers and tuff layers of sand and lake sediments.