MB: Were you involved in the design of Lednock dam?
AA: Yes. It is a buttress dam … the rock was sound enough to take high stresses which you don’t get with more common what we call massive gravity dams which is really like a huge block of cheese spread across the valley. Some thought I was being a bit daring in the process which had been used in the United States a lot.
MB: Was the fact that the dam is in an area earthquake tremor at least was that a consideration in your planning?
AA: Yes, it was. Comrie was noted for it’s earthquakes the 10 years in which most occurred was 1870 to 1880, I think, but anyway because of that I felt there should be some recognition of that made the result of an impact assuming that the dams safe perfectly ok is that the dam has to move with the shock. Therefore the water it drops then the dam comes back and it rises again so the is this undulating pressure on the dam and the shock on the base of the dam when the earthquake passes through. In the case of Lednock the assumption was made that instead of it storing water it was storing an imaginary fluid that was 15% heavier than water. So the mobility in an earthquake was accounted for by imagining the dam to hold a heavier liquid.