Dr. I. R. Qureshi writes the following comments on the recent paper by Price (this Journal131, 553–75):
1. On the average geological strain rate of 3.10−14S−1, a strain of 95% would be produced in a period of one million years and not 10% as is suggested on p.554. I am also concerned that a strain of 10% is considered ‘almost infinitesimal’ by the author.
2. Figures given in Table 2 show that energy varied as the cube of the diameter rather than ‘the diameter varied as the cube of the explosive energy’ (p. 559).
Dr N. J. Price and the editors are grateful to Dr Qureshi for drawing their attention to these two errors:
(1) In lines 1–3, p. 554, the quoted strain-rate would produce a 10 per cent strain in approximately 105 years and not 106 years as stated. The correct time for such a strain to develop at the corresponding strain rate is correctly given in Table 1 of the paper.
(2) Lines 6–7 from the bottom of p. 559 should read “the diameter varies as the cube-root of the explosive energy”.
With reference to his comment and surprise that I should say that 10 per cent strain is “almost infinitesimal” .... I deliberately used this provocative phrase to indicate that a 10 per cent strain is, geologically speaking, very small. However, one could also point out that one of the assumptions of infinitesimal strain theory is that de × de is