Abstrak

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Several powerful earthquakes have struck Padang during recent years, one of the largest of which was an M 7.6 event that occurred on September 30, 2009 and caused more than 1000 casualties. The basic purpose of seismic microzonation is to produce input for urban planning and to supply site specific ground motion data to be used for the assessment of the vulnerability of the non-structure houses stock. A very detailed geological and geotechnical studies were conducted to evaluate the variation of site characterization within the city of Padang. We perform single observations of microtremors at 200 sites in Padang (conducted in 2017). The results enabled us to estimate the site-dependent amplification characteristics of earthquake ground-motion. a 12-sites was surveyed by using microtremor array investigation to gain a representative determination of the soil condition of subsurface structures in Padang. Based on soil characteristic in whole Padang, 1D site response analyses are performed to calculate earthquake characteristics on the ground surface using as many as possible, hazard compatible real acceleration time histories, such as recorded ground motion of earthquake 2009 to obtain predicted ground motion whole Padang for 150 and simulated ground motion for 500 years of return period. This seismic microzonation is a parameter for vulnerability assessment to non-engineered houses. We conduct vulnerability assessment to non-engineered structure of houses stock to estimate current structure condition to face predicted earthquake event in near future (conducted in 2017). We consider representative non engineered structure at each district, around 100 nonengineered structures for each district to be assessed and interviewed. The residents received explanations for each item on the questionnaire from the interviewers, and answers were filled in directly on the answer sheets. A pilot study is carried out to evaluate seismic damage in a district in Padang, Indonesia. The results demonstrate the significance of site characterization and site response analysis in calculating the earthquake characteristics on the ground surface in comparison to simplified empirical procedures.