GEOLOGY AND TECTONIC CLASS STUDY LEMBANG FAULT, WEST JAVA

• Main Author: GAMARA KUSDIWAN, EKA
• Format: Final Project
• Language: Indonesia
• Subjects: Geologi, hidrologi & meteorologi
• Online Access: https://digilib.itb.ac.id/gdl/view/21893
• Institution: Institut Teknologi Bandung

Lembang fault is located about 10 km to the north from the center of Bandung, West Java, has a new segment in the western part. The length of Lembang Fault that previously 22 km, estimated to extend to 29 km to the west, from Mount Palasari in the east to Ngamprah in the west. To understand the condition of new segment of Lembang Fault, this research will discuss geology and tectonic class study to determine the activity of whole segment of Lembang Fault. Geomorphologically, this fault is clearly visible with the fault scarp that separates the descending block in the north and blocks up in the south, but absent in the new segment. The study area is located in the area of the Pre-Sunda - Sunda - Tangkubanparahu volcanic complex. The research area's lithology is dominated by Quaternary volcanic rocks; the Pyroclastic Breccia Unit (15%), the Andesite-Breccia Unit (25%), the Andesitic Lava Unit (7%), the Tuff Breccia Unit (8%), the Basaltic Lava Unit (2%), the Tuff Lapilli Unit (38%), and the Koluvium Unit (5%). All of these rock units (except the Colluvium unit) are truncated by the Lembang Fault, which means that Lembang Fault is an active fault (cutting the Holocene Tuff Lapilli rocks unit). The estimated new segment of Lembang Fault also proved Geologically. An approach to identify Lembang Fault activity is by morphotectonic analysis. This method includes morphometric analysis with tectonic class study. Morphometric analyzes includes Mountain Front Sinuosity, and Ratio of Valley Floor Width to Valley Height. The results of the morphometric analysis shows that Lembang Fault is active fault with high tectonic class.