The Bulli Coal Seam, located in the Illawarra Coalfield of New South Wales, has a long and varied history of sudden
outbursts. From available information this problem has resulted in twelve fatalities over the last one hundred and one
years, with over five hundred separate outburst incidents being identified. These incidents have varied in severity and
intensity from the discharge of 1 to 2 tonne of coal, with a slight increase in gas emission, to the discharge of 200 to 400
tonne of coal with some 6,000 m3 of gas being liberated and large items of mining equipment being pushed 1 to 2 metres
down the roadway.
Geological features associated with these outbursts can be mapped on a regional and mine by mine basis, to provide some
indication or warning. Similarly changes in gas content and gas composition can also be determined on a regional and
mine by mine basis. However sudden geological changes (such as a 6.5 metre seam displacement within 15 metres)
variations in gas content (such as 6 m3/tonne to 15 m3/tonne) and changes in gas composition (from 95% CH4 to 90%
CO2) all within one mine does make the prediction or forecasting of outburst incidents exceedingly difficult.