Seems the Russians were drilling in the far off deserts of Turkmanistan when they punched a hole into a huge cavern. The earth gave way and the fellow(s) in the drilling rig, with the drilling rig, fell through into the deep pit. They could not find the poor fellow but quickly realized that some poionous gases were spreading into the air . . . no doubt the wailing calls of the damned and undead . . . . To stave off the global conquest of the denizens of hell they lit the whole pit on fire.
That was 40 years ago.
You have to hand it to the Russians, they don't mess around, they'll even set hell on fire!