VOLCANIC QUARTENARY STUDY AT MOUNT SUNDA – TANGKUBANPARAHU COMPLEX, BASED ON GRAVITY AND GEOMAGNETIC MEASUREMENT DATA IN KANCAH – CIATER REGION, WEST JAVA

• Main Author: Arisbaya, Ilham
• Format: Theses
• Language: Indonesia
• Subjects: Geologi, hidrologi & meteorologi
• Online Access: https://digilib.itb.ac.id/gdl/view/74401
• Institution: Institut Teknologi Bandung

Mount Tangkubanparahu that lies between city of Bandung and Subang is an active quarternary volcano and located at the caldera of ancient Sunda Mountain. Volcano hazard research needs to be done to raise the volcano hazard awareness, especially in such city on the volcano. Craters at the summit of Mount Tangkubanparahu lined up in an east-west trending pattern that goes younger to the east, and looks like an overturned boat viewed from Bandung. On the northeast slope, there are lava cones lined up forming southwest-northeast trending patern. These phenomena is assumed to be controlled by concealed fault that covered by younger volcanic rock layer. Volcanic activity of this active quaternary volcano can be studied based on the analysis of geophysical gravitational and geomagnetic measurement data, thus sub-surface geological stucture around the volcano is obtained. This study uses geophysical gravity, geomagnet, and magnetotelluric (MT) data at Kancah and Ciater to detect the existance of concealed fault. Bouguer anomaly map, Residual map, also Horizontal Derivative of Bouguer-anomaly's and it's residual map are compiled based on gravitational data. Total-Magnetic-Intensity anomaly map and Reduce-to-Pole map are compiled based on geomagnetic data. Analysis on these maps indicates the existance of concealed fault in a west-east pattern at the summit of Mount Tangkubanparahu which interpreted controls the Mount Tangkubanparahu eruption shift. The analysis also indicates a southwestnortheast patterned concealed fault at the northeast slope of Mount Tangkubanparahu which placed consistents with the location of lava cones appearance. 2D gravitational modelling is also taken on five trajectories and associated to MT modelling taken at Ciater. The modelling uses eight lithology units , which are tertiary sedimentary rocks (basement), Pre-Sunda lava, Pre-Sunda pyroclastic, Sunda lava, Sunda pyroclastic, Tangkubanparahu pyroclastic, Tangkubanparahu lava, and Tangkubanparahu pyroclastic2. The modelling provide an estimate of tertiary sedimentary rocks (as basement) depth at about 4 – 3 kilometers from the earth's surface.