Seismic characteristics of Sumatra and its relevance to Peninsular Malaysia and Singapore

In this paper we first use the great Mexico City earthquake of 1985 to demonstrate that great earthquakes not only cause devastating losses locally, but can also be dangerous to buildings on soft soils several hundred kilometers away. The building responses to some recent earthquakes suggest that in South East Asia, similar scenarios cannot be totally ruled out. Secondly, the cause and the characteristics of teh earthquakes in the Sumatra area are reviewed. Thirdly we present the results of a preliminary investigation into the risk of very large earthquakes in Sumatra. The result indicates that the recurrence interval of an earthquake with a moment magnitude (Mw) of 8.5 or larger is about 340 years, which is equivalent to a 14% probability of exceedance within 50 years. The results imply that the risk of a very large earthquake is high in Sumatra, and that its potential effects on the distant metropolitan areas in Peninsular Malaysia and Singapore should be investigated in further research.