BAND-LIMITED HETEROGENEOUS FRACTAL STRUCTURE OF EARTHQUAKES AND ACOUSTIC-EMISSION EVENTS

Generalized correlation integral functions of the spatial distribution of earthquake epicentres have been determined for the Chinese earthquake catalogue. These correlation integral functions have three distinct power-law regimes (bands), showing that the spatial distribution of earthquakes has band-limited heterogeneous fractal structure. We also found similar results in the hypocentre distribution of acoustic emission events in coarse-grained granite under triaxial compression testing. These results show that the fractal structure in rock fracturing is very complex: they are heterogeneous in space and also band-limited in scale. The spatial distribution of fractures shows different patterns corresponding to different scale ranges: microcracks in rock samples, earthquake epicentres in seismic clusters, seismic clusters along active fault zones (boundary of crustal block, for the most cases), and active fault zones in the earth's crust. The fractal dimension differs corresponding to the scale bands indicating there are some intrinsic characteristic scales existing in the fracturing system, such as grain size and size of crustal blocks.