This Safety Guide supersedes the 2010 edition of IAEA Safety Standards Series No. SSG?9. It takes account of recently gained knowledge and practices developed by Member States related to seismic hazards, especially lessons from the Fukushima Daiichi accident. It also addresses concomitant events associated with earthquakes, such as tsunamis. The revision provides a clearer separation between the process for assessing the seismic hazards at a specific nuclear installation site and the process for defining the related basis for design and safety assessment of the nuclear installation. Thus, it bridges gaps and avoids undue overlap of the two processes, which correspond to and are performed at different stages of siting of the nuclear installation.