Fractal structure of spatial distribution of microfracturing in rock

Abstract

A constant stress fracture experiment of Oshima granite was carried out at the confining pressure of 40 MPa. Hypocentres of 2064 acoustic emissions were located during the experiment. Using the ‘correlation integral’, we found that the spatial distribution of hypocentres of acoustic emission is a fractal, and that the fractal dimension decreases with the evolution of rock fracturing. The spatial distribution of earthquake's hypocentres reveals fractals ranging from regional to worldwide distribution. If we extrapolate from laboratory measurements, it is possible to predict the occurrence of large earthquakes by the decrease in the fractal dimension.