Since then there have been significant advances in the seismic design of dams and a revised Bulletin is considered necessary which takes into account current practice in a number of countries with the following ends in view:

• To provide a guide for the selection of parameters to be used in the seismic design, analysis and safety evaluation of new or existing dams and their appurtenant structures.
• To promote consistency in handling the earthquake aspects of dam performance evaluation among owners, designers and various organizations involved in the planning, design, construction, operation, maintenance and regulation of dams.

This bulletin revision comes after several years of work by the Committee on Seismic Aspects of Dam Design and has, in particular, addressed the following aspects:

• A new section on Seismic Input parameters.
• Reference to liquefaction.
• Introduction of Safety Evaluation Earthquake (SEE).
• Improved references to problems posed when constructing dams across active faults.
• Improved references to Reservoir-Triggered Earthquakes (RTE).
• Additional material on Peak Vertical Accelerations and Earthquake Durations.
• Updated references to attenuation formulae
• Updated list of references.