Catastrophic sliding over a fault caused by accumulation of dilation zones
A mechanism of rockburst caused by a sudden sliding over a fault repeatedly subjected to local sort-time tensile loads (eg, by tensile phases of incident waves caused by blasting operation or by neighbour seismic events) is considered. It is assumed that, normally, friction between rough faces of the fault prevents their sliding. The action of each local tensile load however opens a part of the fault enabling local sliding and formation, due to the interaction between rough faces, of a dilation zone. As the dilation zones accumulate their interaction enhance this process, which eventually makes the average size of the dilation zones equal to the average distance between the centres of the zones. This will cause their coalescence and, hence, the formation of a macro-zone of sliding. This may be interpreted as a catastrophic sliding which is a major seismic event. A model is proposed which allows a prediction of the catastrophic sliding and the evaluation of the magnitude of the seismic event. Two simple methods of computing the interaction between randomly located dilation zones are used: the self-consistent method and the approximation of periodic locations. It is shown that both methods give similar results.