Faults & Folds

As coal deposits form a fairly brittle ore body, when they are subjected to major tectonic disturbances such as faulting, folding and shearing, they can suffer a high degree of fracture with low shear resistance. To support this, outburst studies show that the presence of fractures and shear zones coexist with outburst prone areas. The shear zones indicate the presence of excess stress and planes of weakness and also the existence of pockets of gas and pulverised coal (Doyle, 2002).

All fatal outbursts in Australia (except Leichhardt Colliery) have occurred on faults. This is not to say that all faults will show the occurrence of outburst. The types of faults most likely to be associated with outbursts are low angle reverse faults and strike-slip faults. Between the faults, mining conditions are generally good. The magnitude of the fault often bears no relationship to the magnitude of the outburst.