Seismic hazard assessment of Singapore - Effects of long-distance major earthquakes

Singapore, a city state with a population of about 3.4 millions and an area of about 600 km(2), is located in a low seismicity region. It is 400 km, at the closest distance, from the highly active Sumatra earthquake belt, where large earthquakes have occurred in the past. The construction of high-rise buildings and complex infrastructure systems has taken place rapidly since early 1970s. Since there has never been any earthquake damage reported in the modern history of the country, structures are not specifically designed against horizontal earthquake loading. The current Singapore building code is mainly based on British Standard (BS 8110 Code), which has no provision for seismic loading. Although Singapore is located in a low seismicity region, the present study shows that the seismic hazard potential in the country is not negligible, especially the damage potential to the high-rise buildings constructed on soft sedimentary deposit in the south-eastern coast. Microtremor measurement results have confirmed the correlation between building response to the long-distance Sumatra earthquakes and the local geological conditions. Moreover, as experienced in the recent Bengkulu earthquake, a large earthquake in Sumatra has a potency to generate tremors that could cause high-rise buildings in a wider area to vibrate perceivably.