RESULTS OF SITE-SPECIFIC GROUND RESPONSE ANALYSIS

Abstract

The city of Banda Aceh-Indonesia is extremely exposed to a significant seismic hazard. There are three main seismic sources around the city which are the tectonic subduction, the great Sumatran fault, and the West Andaman fault. Thus, seismic microzonation study of the Banda Aceh city is urgently required for any mitigation efforts. Site-specific ground response analysis was carried out at eleven sites in the city of Banda Aceh. An analytical model of the equivalent-linear model was used to perform ground response analysis. This
analytical model of the equivalent-linear approach has demonstrated that it can simulate, reasonably well, the alteration of seismic motions at the ground surface. Three actual historical time histories recorded at rock sitesnearby the city of Banda Aceh, and eleven developed sub-surface models in the city of Banda Aceh, were used to estimate the seismic characteristics, namely the peak ground acceleration, peak ground velocity, fundamental frequency, and estimated site amplification of the investigated sites. The results of the site-specific ground response analysis suggest that: (1) all the eleven sites have been classified as seismic site class D as per the
provisions of SNI 1726-2012; (2) the site fundamental frequency in the city of Banda Aceh varies between 0.2 and 1.1 Hz; and (3) the amplification factor of the soils in the city of Banda Aceh can be up to 4.7. The largest spectral velocity and acceleration of the investigated sites were found to be 0.26 cm/s and 0.29 g, respectively.