Earthquake Hazard And Risk In Regions Of Low To Moderate Seismicity

Historically building design in many parts of world does not consider seismic loading. While this is clearly not appropriate for regions of high seismicity it is probably sensible for regions of low seismicity. The question addressed by this paper is whether the cut-off level for seismic design as proposed by the US International Building Code (IBC) is reasonable.

This paper presents some key issues regarding the nature of seismic ground motion hazard and how to assess whether it is sufficiently large to require it to be considered in the design of buildings. It begins by summarising some observations from the 1985 Mexico City and 1989 Newcastle earthquakes with regard to building damage and site response effects. These observations are followed by an overview of seismic hazard and risk studies carried out by the author for the United Kingdom, Hong Kong and the Malay Peninsula. These studies were carried out in the early 1990’s, 2000’s and 2008 respectively. Partly because of this range of timing, and the widely different nature of the building stock, the methodologies used for these studies have developed. The underlying results however show that the IBC gives reasonable guidance as to when seismic ground motion can be ignored.