SUBSURFACE STRUCTURE MODELING OF ACEH SEGMENT OF SUMATRAN FAULT AREA USING THE GRAVITY METHOD

• Main Author: Roudhatu Rohmah, Asla
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/76761
• Institution: Institut Teknologi Bandung

The aim of this final project is to model and analyze subsurface structures based on density distribution in the Aceh fault area using the gravity method. Indonesia is a country located on the ring of fire and is squeezed by three plates, namely the Eurasian plate, the IndoAustralian plate and the Pacific plate. This geographical location causes Indonesia to experience disasters in the form of volcanic eruptions and earthquakes. So it is necessary to identify the subsurface structures of the earth in order to minimize the impact of these natural disasters. Identification of the structure of the earth's surface begins with data collection carried out at the Aceh Fault, Nanggroe Aceh Darussalam using the gravity method. The gravity method is an indirect method in geophysics. This method can be used to determine subsurface geological configurations on a broad scale based on the density differences of each rock. The gravity method is based on variations in the acceleration due to gravity on the earth's surface. The result of the gravity method is a density distribution that can describe the subsurface structure. The tool used is the scintrex gravimeter. After data collection, data processing is carried out. Data processing is done with the help of Oasis Montaj software. The gravity value has retrieved from the data of CBA is -208.6 mGal to 66.1 mGal. The density value is 2.256 g/cm3, can be found by Parasnis method. Rock density contrast shows the presence of faults with a depth of 1.2 km on the A-A' track, a depth of 3.2 km on the B-B' track. Sandstone and alluvium form faults in the A-A' track, while tuffaceous sandstone, alluvium and limestone form faults in the B-B' track.