If you have never played the video game or seen the film, Silent Hill involves a town shrouded in mist and fog, road blocks closing it off from the rest of the world. The protagonist and his/her child (depending on whether we are talking about the movie or the game) have a car accident near one of the road blocks. When the parent wakes up, the child is gone. With no other option, they are drawn further into a world of monsters, madness and pretty much everything you can imagine in 'Hell on Earth'.
But enough of the fictional Silent Hill. Above is a Google aerial view of Centralia, Pennsylvania. Even from this high up, you can see that something looks wrong. A traditional grid system of roads, but no buildings.
In 1962, a load of rubbish was piled in a landfill and burned. Nothing wrong with that, after all we still incinerate all sorts of waste today. Just one problem though, the hole in the ground chosen for the bonfire was an abandoned strip mine. See, coal mining was big in Pennsylvania. Unfortunately, no one put two and two together and guessed that it might not be a good idea to risk setting fire to millions of tons of coal running under their town.
Well, the fire department showed up and doused it with water and they thought that was that, but a few days later the pit had erupted in flames again. This time they poured water on it for hours but it was too late, the underground seam had ignited.
Over the next twenty years, fire fighters threw everything they could at the problem. They poured water and ash on it, dug out burning material, dug trenches and backfilled and drilled thousands of holes to monitor the spread of the underground fire. Nothing worked.
In the 70s, the local gas station owner started to worry about the underground heat and dipped his storage tanks with a thermometer. The petrol stored underground was 180 degrees fahrenheit.
By the early 80s, the fire covered an area of 200 acres and carbon monoxide levels had risen to dangerous levels. Homes had to be abandoned. A study concluded in 1983 that the fire could burn for another 100 to 250 years (some studies quote 'up to 1,000 years) and might spread to an area of 3,700 acres. The US government started to buy up the now unsafe houses and buildings and relocating residents, although several die hard Centralians refuse to leave.