This town has been on fire for five decades and might burn for another 250 years

In what seems like the plot to a disaster movie, the quiet town of Centralia, Pennsylvania has endured a burning problem since 1962: It's been on fire, literally, for more than five decades.

And how this fire started still remains a mystery. But chemistry can help explain why it's still going.

The problem runs deep

Centralia, Pennsylvania sits atop a few of the biggest coal deposits in the world. This was fortuitous for the sleepy town at the time because coal was - and still is - one of $4 and electricity, having fueled the Industrial Revolution.

In the 1800s, miners in Centralia blasted tunnels underground to harvest the coal, but by the mid-1900s, many of the mines where abandoned.

No one knows exactly how the Centralia fire started, but the strongest theory is that burning trash from a nearby landfill accidentally ignited coal below an old entrance to the mine. The fire then spread through the mines

Feeding the flames

Coal is formed over millions of years when $4 under sand, mud, and other natural materials. The pressure on the organic matter increases as layers of earth above it grow over time, and all of the water and other substances from the buried plants and trees get squeezed out, forming coal that ends up being mostly carbon - $4.

When the carbon inside coal mixes with oxygen, it ignites. It can even begin $4 without a flame nearby.

Those tunnels that the miners dug in the 1800s fed the flames by siphoning in oxygen from the surface. Then, as more coal burned, the flames bit deeper and deeper into the surrounding region - $4 - in a vicious, fiery cycle that wouldn't stop.

Coal burns slow and steady, which means that it takes a very long time to burn out. This is unlike timber in a forest or a camp fire, which smolders quickly.

As long as there's enough heat, fuel, and oxygen to keep it going, the fire won't burn out. Because coal contains a natural source of fuel - carbon - it can keep burning for as long as there's enough heat and oxygen to keep it going. This is why coal mine fires can blaze for centuries.

Today, the Centralia fire covers $4.

Shockingly, it could burn for another 250 years.

Eternal Flame

The 1,000 residents that lived in Centralia at the time thought the fire was a silly inconvenience at first. But that changed when $4, nearly suffocating them in their homes. The underground fire also fractured the ground, making sinkholes pop up all over the place. $4.

The town has tried in vain to snuff out the flames over the years. They drilled holes into the mine and plugged them up with wet sand to choke off the air supply, but it didn't work. $4 and haven't made another attempt since.

The state government condemned Centralia in 1992 and almost all of its residents left. Today, just about a dozen people live there. The town has been $4.

While a long-burning, underground fire may seem like a freak occurrence, $4. Today, mine fires are burning in New Zealand, Wyoming, India, China, and Turkmenistan.

Fires like this also exist naturally too, with $4.

Our friends a the American Chemical Society made a $4 about the Centralia fire on their $4. Check it out for more fiery details.