[jennyyang]

What exactly is burning at this point? I would suspect there is little oxygen left down there. Is it some other form of chemical reaction? They can't just dump boatloads of water to douse the flames? There appears to be enough water for things like fracking, we can't do the same here?

[alamortsubite]

The scope of the problem is huge. Oxygen can enter from a highly elaborate network of abandoned mines and boreholes that stretch for miles, as well as any number of surface fissures. As far as the coal component, keep in mind that this region has the highest concentration of anthracite in the world.

[Hamuko]

If there's smoke coming out, wouldn't it mean that there's a route for oxygen to get in?

[jennyyang]

If that's the only route in, then no. Because most of that is expelled gasses due to heat, there's no way that oxygen could go in if the gasses and smoke were being driven out by the fire.