抄録
Scholz et al, explained precursory phenomena and their durations before earthquakes by dilatancy of the crust, and proposed the relation between the duration period and the magnitude of the earthquake expected which is quite near to the relation proposed by the writer in 1969. The writer also points out the duration period due to dilatancy must be shortened for an earthquake larger than M7, 0 and disappears larger than about M7, 7.
