That had nothing to do with coal
mining, per se, though. The spark was set off in a hole in the ground made by previous mining, yes, but it was an entirely-untapped coal vein that caught fire, and basically anything could have caught it on fire if it was ever exposed to surface air. (A meteorite impact, or earthquake fissure, or sinkhole collapse, could have made a similar crater and exposed the coal vein, for example.)
Centralia is more of a weird natural disaster. It's essentially a slow-motion, underground forest fire. And, like most forest fires, while usually a human with a match is the proximal cause, if the human wasn't there, nature would still have supplied a spark eventually.
