This Safety Guide provides recommendations on a generally accepted way to design a nuclear power plant so that an earthquake motion at the site will not jeopardize the safety of the plant. It also gives guidance on a consistent application of methods and procedures for analysis, testing and qualification of structures and equipment so that they meet the safety requirements covering the design of nuclear power plants, safety assessments for the design and the regulatory issues concerned with the licensing of plants. Contents: 1. Introduction; 2. General safety concepts; 3. Seismic design; 4. Generalities on seismic qualification; 5. Qualification by analysis; 6. Seismic qualification by means of testing, earthquake experience and indirect methods; 7. Seismic instrumentation; Appendix: Samples of seismic categorization.