NOISE AND SITE RESPONSE CHARACTERIZATION IN MAKASSAR STRAIT AND CELEBES SEA BASED ON OCEAN BOTTOM SEISMOMETER (OBS) DATA

• Main Author: Cyiena Christi N, Widjra
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/67883
• Institution: Institut Teknologi Bandung

OBS data were analyzed using passive seismic methods to determine the characteristics of noise and site response in the Makassar Strait and the Celebes Sea. Probabilistic Power Spectral Density (PPSD) from OBS station showed microtremor in the period 0.06 – 0.7 s, secondary microseismic peak in the period 0.9 – 2 s, secondary microseismic peak in the period 4 – 8 s, and hum in the period more than 10 s. The amplitude of the noise power is in the range of New Low Noise Model (NLNM) and New High Noise Model (NHNM) for a period <10 s and slightly above NHNM for a period >10 s for OBS IGGCAS F-type. For OBS IGGCAS G-type, the noise power amplitude is in the period < 0.7 s in the NLNM and NHNM ranges. However, there is a tendency for the noise power amplitude to be flat with an amplitude above NHNM for a period > 0.7 s. The amplitude of the noise power depends on the location of the station, climate, instruments, daily variations, and seasonal variations. Horizontal-toVertical Spectral Ratio (HVSR) in the North Makassar Strait shows an H/V curve with an unclear peak in the middle of the strait and multiple peaks in the eastern part of the strait with frequency range of 1.35 – 4.7 Hz. Between the Makassar Strait and the Celebes Sea, the H/V curve shows a flat peak and multiple peaks with frequency range of 1.10 – 4.03 Hz. Meanwhile in the Sulawesi Sea, the H/V curve shows an unclear peak (unclear peak) and several peaks (multiple peaks) with frequency range of 0.65 – 6.25 Hz.7