I wish to thank the British Geotechnical Society for the opportunity of visiting London’ again and for the honour of appearing before you in the home of the Institution of Civil Engineers, of which I am so proud to be a member. Several years ago I transmitted some preliminary notes on the topic of earthquake effects on dams to the late Karl Terzaghi, whose invaluable advice and suggestions regarding those notes were freely used in the preparation of this Paper. I wish also to acknowledge the comments and suggestions I have had from time to time concerning the subject from my colleague at the University of Illinois, Dr Ralph B. Peck ; from my associate in several consulting assignments, Dr Laurits Bjerrum ; and from my colleague for several months, while he was visiting the University of Illinois, Dr Tu’. N. Ambraseys. Finally, I should like to acknowledge the assistance on some of the calculations for this lecture that were made by two of my associates at the University of Illinois, Dr John W. Melin, and Mr Mohammad Amin.