The spatio-temporal correlation of micro-earthquakes occuring in a mining-induced seismic system (Creighton mine, Ontario, Canada) is investigated. It is shown that, when considering only the after-events correlated to a main event, i.e., not accounting for the uncorrelated regime of `background' activity, the spatial distribution of these after-events occuring at t after the main event change with t. This change takes the form of an expanding pattern, characterized by a typical scale L-c(t) varying as L-c(t) similar to t(H), H being estimated to 0.18. This diffusion exponent is found to increase when considering only a subset of the most energetic events as mainshocks. We interpret this result as the indication of a stress (sub-)diffusion mechanism, involving propagation on the heterogeneous fractal fault network.
|Journal||Geophysical Research Letters|
|Publication status||Published - Dec 1999|