ON THE NEEDS TO CARRY OUT SITE SPECIFIC SEISMIC HAZARD ANALYSIS

The seismic hazard at a site may normally be found from risk maps produced by a country's authorities. In several situations, however, in particular for the design and construction of new and important infrastructure or new and large industrial facilities, a site specific seismic hazard analysis should be carried out. Such situations or facilities are discussed with emphasis on the safety to personnel (in particular to third party personnel) and the environment. It should be noted that the seismic hazard maps resulting from such analysis normally will refer to bedrock acceleration levels and that any amplification effects due to local soil conditions must be taken into account additionally. We discuss examples of the benefits resulting from site specific seismic hazard analysis, either where increased safety is obtained or where the seismic hazard analysis has proven cost efficient. In any case a site specific analysis will be considered to be more accurate than the results of a regional study and the benefits of obtaining a most accurate design basis for a project or a new and updated risk map for political decision making is of value by itself in order to build safer structures (for people and the environment) and to make the best possible decisions for economical investments.