Fundamental Research

Our fundamental research focuses on the main differences between processes leading to earthquakes and the seismic rock mass response to mining. In earthquake seismology the driving forces are fairly constant and relatively slow facilitating the processes of self-organisation. Rock mass subjected to such a process would migrate towards a subcritical state - a state at which the correlation length becomes comparable with the system size and at which the system can develop and maintain reproducible relationships among its distant parts. It is assumed that the growth of long-range correlations within the rock mass allows for progressively larger events to be generated. An important agent in the development of spatial and temporal correlations is seismic activity itself. By breaking numerous asperities, seismic events smooth the system, allowing transfer of stresses over larger distances and thus paving the way for even larger events.

In mines, the rate of the transient convergence associated with rock extraction is at least an order of magnitude greater than that of crustal deformation, which imposes different dynamics on rock mass excitation and on the relaxation processes that follow. If excitation is strong the relaxation process is intermittent with diverging relaxation time and accumulated loading. It is therefore important to appreciate the spatial and temporal extent of these processes.

Mining is not a spontaneous process. It induces stresses at a particular place, at a particular time and at a particular rate, which are all highly variable compared to the tectonic regime This process is controlled more by the commodity prices than by the plate tectonics. This intermittent dynamics influences the development of spatial and temporal correlations and interfering with the act of self-organization. In general mining scenarios that induce spatial and temporal heterogeneity, or disorder, that de-correlate the system are less likely to develop larger dynamic instabilities.