TECTONIC GEOMORPHOLOGICAL ANALYSIS OF RAWA PENING AND SURROUNDING AREAS, CENTRAL JAVA PROVINCE

• Main Author: Zain Burhanuddin, Farhan
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/69390
• Institution: Institut Teknologi Bandung

Indonesia is located in the interaction of the movement of the world's large plates, which affects the deformation and structural arrangement in the territory of Indonesia to be very complex. This is reflected in the island of Java, which is in the convergence zone between the Indo-Australian Plate and the Eurasian Plate, so that this island becomes a zone of volcanoes and active faults. One of the active faults mapped is the Rawa Pening Fault, which passes through Semarang Regency and Salatiga City, Central Java. Historically, the area has experienced quite destructive earthquakes, and on 24 October-5 November 2021, 42 swarm earthquakes occurred. The Rawa Pening and its surroundings area are also dominated by Quaternary-aged rocks, which if deformed can be an indication of an active fault. Therefore, research on the Rawa Pening Fault needs to be carried out, to determine the level of activity, lineaments, and movement. This research was conducted in the area around Rawa Pening which is part of the Tuntang watershed, with tectonic geomorphological analysis using morphometric and morphotectonic methods. The morphometric method uses five geomorphic indices, including Hypsometric Curve (Hc) and Hypsometric Integral (Hi), Asymmetry Factor (AF), Knickpoints (Ksn) and Stream Length-Gradient Index (SL), Mountain Front Sinuosity (Smf), and Ratio of Valley Floor Width and Valley Height (Vf). All index values are weighted to obtain the value of the Index of Relative Tectonic Activity (Iat). The results of the calculation, the area with Class I (very high) Iat has an area of 6.90 km2 (1.42%), Class II (high) has an area of 344.11 km2 (71.01%), Class III (moderate) has an area of 60.95 km2 (12.58%), and Class IV (low) has an area of 72.62 km2 (14.99%). The very high Iat value is in the vicinity of the Rawa Pening Fault. The morphotectonic method is carried out by analyzing the lineaments from digital elevation model (DEM) and data from field observations. The morphology found in the form of scarps, wind gaps, knickpoints, river bends, and other structures associated with the faults. The lineaments and landforms indicate the path and movement of the Rawa Pening Fault which has a thrust and sinistral strike-slip component.