TECTONIC GEOMORPHOLOGICAL ANALYSIS OF SOURCE OF THE EARTHQUAKE ON DECEMBER 14TH, 2021, FLORES SEA

• Main Author: Aleanry Putra, Indika
• Format: Final Project
• Language: Indonesia
• Subjects: Geologi, hidrologi & meteorologi
• Online Access: https://digilib.itb.ac.id/gdl/view/78872
• Institution: Institut Teknologi Bandung

On December 14, 2021, there was an earthquake located under the Flores Sea, East Nusa Tenggara with a mainshock magnitude of 7.4. The earthquake was located in the Flores Sea, precisely in the northern part of Flores Island, Nusa Tenggara Islands, with the hypocentre of the main shock located approximately 100 km to the north of Flores Island with a depth of 10 km (shallow earthquake type). Based on the focal mechanism, the earthquake that occurred in the study area (Flores Sea, East Nusa Tenggara) was triggered by the movement of an active fault of the rightlateral strike-slip fault type. The strike-slip fault that triggered the earthquake has not yet been mapped, as evidenced by the absence of strike-slip fault on maps of active fault distribution in the research area in existing scientific journals. No research has mapped the existence of the strike-slip fault that triggers the submarine earthquake, so the position and continuity of this strike-slip fault is still unclear. This study aims to map the active faults in the research area including the main fault that triggered the December 14, 2021, Flores Sea earthquake, in Indonesia. The mapping of these submarine faults was carried out using the MultiBeam EchoSounder (MBES) survey method. The results of the MBES method are in the form of point cloud data and will be processed in such a way as to become bathymetry data. Tectonic geomorphology analysis was conducted on the bathymetry data obtained from the MBES survey to see the existing geological structure in the research area based on its geomorphological appearance. The existence of active faults and their subsurface state can be known through existing seismic data and earthquake catalog data. Based on the tectonic geomorphology analysis and seismic analysis that has been carried out, it is found that there are right-lateral strike-slip faults that are active in the study area. There is also a main fault in the form of a right-lateral strike-slip fault with a length of approximately 130 km which has a northwest-southeast direction in the southern part of the study area and a west-east direction in the northern part of the study area. There are also several fold ridges formed by the activity of the Flores back-arc thrust faults in the southern part of the study area. There are also some geomorphology units in the study area that were formed due