The Ishimoto-Iida's statistical formula is described as follows:
nam=k
where, a is a traced maximum amplitude; n is an annual average frequency of small shocks with a, while m or k is a constant at that place.
What interests us, the same statistical form holds good in the maximum amplitude distribution of cracks, occurring naturally in an earthen wall or in that of cracks in a glass sheet artificially produced by heat.
