GEOLOGY AND GEOMORPHOLOGICAL CHARACTERISTIC OF LEMBANG FAULT, WEST JAVA

• Main Author: ROSANAWITA (NIM : 22410308); pembimbing: Ir. Benyamin Sapiie, Ph.D ; Dr. Eko Yulianto, PRETTY
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/19157
• Institution: Institut Teknologi Bandung

Lembang Fault, which is located 10,7 km northward from the center of Bandung city, West Java, has length about 22 km, elongated from Cisarua in the west to Mount Pulusari in the east. Geomorphologically, this fault can be observed obviously because there is a significant topographical difference between the north and the south block. Geologically, this fault is still debatable, especially about the time and mechanism of its formation. Due to the importance of information about geometry and movement of a fault, as an input data for seismic hazard measurement, then this research will be focused on geology and geomorphological characteristic of Lembang Fault.By using high resolution satelite image data, the geomorphology unit and the lineament pattern around Lembang Fault area are being classified. Geological data, like litology description and secondary structures, which are found by field observation, are used to confirm the stratigraphy unit strata that related to Lembang Fault and to analyze the fault kinematic. Then, supported by dating data from previous research, the history of Lembang Fault formation is being constructed. Beside that, the satelite image data also used to analyze the geomorphological phenomena which is observed at Lembang Fault, in order to obtain its segmentation and movement characteristic.Based on geological data analysis, including geomorphology, stratigraphy, and structure, the East Lembang Fault was formed previously before the West Lembang Fault, in which around 200.000 – 180.000 years ago for the east and 24.000 – 62.000 years ago for the west. The forming mechanism of both of them is similar, as circumferential dike which is collapsed during the caldera formation. The difference between both of them is the volcanic activity that correlated with their formation, which is Sunda Volcano for the east segment and Tangkubanparahu Volcano for the west segment. The tip point of these two segment is located between Cihideung River and Gunung Batu, which is geomorphologically indicated the appearance of bulging area on that transition zone. The dip of West and East Lembang Fault is not too different, which are 30º - 45º and 35º - 50º respectively. Based on the kinematic and geomorphological characteristic analysis, it is inferred that Lembang Fault has recent sinistral movement indication for the horisontal component, which is related to the present day tectonic activity.