[jmhobbs]

Underground coal fires like the Centralia mine fire are an interesting and not as well known problem as oil spills.

> The fire is burning in underground coal mines at depths of up to 300 feet (90 m) over an 8-mile (13 km) stretch of 3,700 acres (15 km2). At its current rate, it could continue to burn for over 250 years.[2]

https://en.wikipedia.org/wiki/Centralia_mine_fire

[Fej]

Is there no way to put it out? Starve it of oxygen? Tons of water?

[wbl]

The area is cracked enough you would never be able to fill the whole seam.

[DrScump]

Sequester CO2 there? Helps on two levels.