ABSTRACT
Introduction Over the centuries all human civilisations have been threatened by natural hazards like hurricanes, floods, droughts, earthquakes, etc, that claimed the lives of individuals or entire groups bound by their residence or profession. Many activities have been deployed to protect man against these hazards. Even today money is spent to avoid or prevent natural hazards, because the consequences in developed societies have increased considerably. Other more recent hazards are man-made and result from the technological progress in transport, civil, chemical and energy engineering. One of the tasks of human civilisations is to protect individual members and groups against natural and man-made hazards to a certain extent. The extent of the protection was in historic cases mostly decided after the occurrence of the hazard had shown the consequences. The modern approach aims to give protection when the risks are felt to be high. This gives rise to the rather novel idea of acceptable risk.
