SUBSURFACE IMAGING OF MAKASSAR STRAIT AND SURROUNDING AREA USING AMBIENT NOISE TOMOGRAPHY METHOD

• Main Author: Chandra, Carina
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/67882
• Institution: Institut Teknologi Bandung

Sulawesi Island is constructed from complex tectonic activities as a result of the collision of Indo-Australia, Eurasian, and Pacific plates. This produced interesting structures such as faults, basins, and subduction zones. The Palu Fault currently plays a dominant role in the tectonics of Sulawesi. The active fault, known as the Palu Koro Fault, extends almost north-south through Makassar Strait and intersects with a subduction zone in the Celebes Sea. The highly complex tectonics of Celebes Sea, Makassar Strait, and the active Palu Koro Fault since its early formation days has generate hazards such as earthquakes and tsunamis. This becomes a concern for geoscientists to research the area further. One of the methods used in subsurface imaging is the Ambient Noise Tomography (ANT). This tomography method uses seismic source in the form of ambient noise that can be recorded anytime and anywhere. The resolution of the tomographic image with this method depends solely on the distribution of the existing seismograph network rather than the occurrence of earthquakes. Sufficient data for higher resolution subsurface imaging of the Celebes Sea and Makassar Strait is obtained from Ocean Bottom Seismometer (OBS) data. OBS is an underwater device that includes a 3- component seismometer and one hydrophone. This device can record long-offset seismic or seismological data. In this thesis, phase weighted stacked OBS and linear stacked land ambient noise data obtained by Cambridge-ITB are used to acquire a subsurface image of Makassar Strait and its surrounding area with higher resolution. The acquired Rayleigh wave group velocity model shows velocity contrasts with higher velocities in the Celebes Sea subduction zone and the middle parts of the North Makassar Strait associated with sedimentary rocks, and lower velocity along the Palu Koro Fault extending through Central Sulawesi associated with metamorphic complex and granitoid intrusion.