SUBSURFACE STRUCTURE ANALYSIS OF PAPANDAYAN VOLCANO CRATER AREA BASED ON 3D MODELING GRAVITY METHOD

• Main Author: Tio Miranda, Debora
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/71167
• Institution: Institut Teknologi Bandung

There are 127 active volcanoes in Indonesia that spread from the east to the west. One of them is the Papandayan Volcano located in Garut, West Java. Papandayan Volcano is a type A volcano because it erupted in 1772. The last major eruption occurred in 2002, which resulted in a disaster. Therefore, the activity of this mountain needs to be monitored regularly, one of which is by understanding the distribution of the subsurface, which can be known through geophysical surveys. One of them is the gravity method. This method uses the value of the acceleration due to gravity to determine the subsurface structure of the earth. In this study, measurements were carried out using the LaCoste & Romberg G-928 Gravimeter with three paths of 106 points. The value of the gravitational acceleration reading can be affected by the environment and the fatigue of the measuring instrument. The existence of these factors makes the acceleration value obtained must be corrected. From the corrections, the Complete Bouger Anomaly (CBA) value is obtained. CBA values are in the range of 1585 mGal to 1700 mGal. Then the regional anomaly and residual anomaly are separated. From the residual anomaly, intersecting slicing will be made. Slicing results are used for modeling to determine the distribution of subsurface density values. From the models, it can be interpreted that in the study area, there are low density distribution of sedimentary rocks, which are pyroclastic deposits originating from volcanic activity and oriented from south to north. Whereas igneous rock with a high density forms a basin that represents as the Papandayan volcano's basement.