"The general conditions under which water influx and gas leakage occur as a result of subsidence and the associated fracturing of the overlying confining layer are examined. The effects of fracture width, fracture density and permeability of the confining layer on water influx are determined. An expression is developed for the time (Tc) required for critical saturation of the coal seam. Numerical values of T c are presented for a wide range of permeabilities and coal seam thicknesses."