| Abstrak/Abstract |
In this study, we investigated the shaking characteristics of the ground under Palu City. We carried out array observations at eight sites in Palu City. Dispersion curves were calculated using the SPAC method. Four accelerometers were used in each array observation site. One was installed at a center of the circle with a radius, r. Other three were arranged on the circle with a shape of regular triangle. Observation duration time was 20〜30 minutes and sampling frequency was 100 Hz. Sequential observations were conducted three times by changing the array radius; r=3, 10 and 30 meters. Then, a substructure profile was identified from the dispersion curve by using the Particle Swarm Optimization. From the dispersion curve of array observations, the central business district of Palu corresponds to relatively soil condition with Vs ≤ 300 m/s, the predominant periods due to horizontal vertical ratios (HVSRs) are in the range of 0.4 to 1.8 s. Several powerful earthquakes have struck along the Palu-Koro Fault during recent years, one of the largest of which was an M 6.3 event that occurred on January 23, 2005 and caused several casualties. Strong ground motions of the Palu area were predicted based on the stochastic Green’s function method. Peak ground acceleration becomes more than 400 gal in some areas, which causes severe damage for buildings in high probability. |
