Author : H.Andayany*, J. R. Kelibulin and P. Nanlohy
The research was carried out around the coast of the Outer Ambon Bay which is located on the island of Ambon. The purpose of this research is to determine the value of the dominant frequency and seismic vulnerability index. Data retrieval was carried out using TDL 303S Seismograph at 30 measurement points with spaces between measuring points 200 to 500 m. The results of microtremor measurements were analyzed using the Horizontal to Vertical Spectral Ratio (HVSR) method to obtain the dominant frequency value (f0) and amplification factor (A), so that the value of the seismic vulnerability index (kg) can be determined. The dominant frequency values obtained ranged from 0.634 Hz to 13.424 Hz, the amplification values obtained ranged from 1.011 to 1.957 and the value of the seismic susceptibility index obtained ranged from 0.143 cm/s2 to 2.338 cm/s2. Based on the dominant period, it is known that the measurement location in the coastal area of Teluk Ambon Subdistrict (Location 1-15) is generally dominated by class II land types which are composed of alluvial rocks, with a depth of 5 m consisting of sandy - gravel, sandy hard clay, loam. Whereas the measurement point 22-30 which is the coastal area of Nusaniwe Subdistrict is generally dominated by class IV soil types composed of alluvial rocks, which is formed from delta sedimentation, topsoil, mud, etc., with a depth of 30 m. Key words: Microtremor, HVSR, Dominant Frequency, Amplification Factor, Seismic Vulnerability Index.
Dr. Arend L Mapanawang, Sp.PD, FINASIM, PhD