(WHTM)– Eternal flames are flames that continuously burn for an extended period of time, often indefinitely. This natural phenomenon doesn’t occur often, but there happens to be one right here in Pennsylvania.

According to National Geographic, eternal flames can occur when underground natural flammable gas travels to the surface through fractures in holes and rocks. The constant fueling of gas can often cause these flames to burn forever.

National Geographic says this rare phenomenon can be found worldwide, with one of the most notable locations being the “Gate to Hell” in the Karakum Desert in Turkmenistan.

The United States is home to multiple infamous eternal flames, including Eternal Flame Falls in New York.

Pennsylvania’s eternal flame is bigger than a flickering fire under a waterfall. It actually caused the majority of an entire town to evacuate more than 40 years ago.

Most Pennsylvanians are familiar with the now ghost town of Centralia, which was once home to more than 1,000 people.

According to Britannica, Pennsylvania is home to some of the largest coal deposits in the world, which led miners to tunnel beneath the earth and harvest coal. Many of these mines were abandoned by the mid-1900s, one of which was under the town of Centralia.

While Pennsylvania has multiple active mining fires, Centralia stands out among the rest due to its longevity and historical relevance.

It is unclear how the Centralia fire started in 1962, but 53 years later, it’s still burning.

Britannica says coal burns when the carbon inside it combines with oxygen, and the tunnels below Centralia provided perfect conditions for a lasting fire. The fire in Centralia didn’t seem like a problem at first, but toxic fumes emanating from the ground soon began to push residents from their homes.

Additionally, the fire weakened the ground, leaving the area prone to sinkholes, Britannica said.

According to History.com, Pennsylvania condemned Centrailia in 1992, forcing the town’s remaining residents out. Thrill seekers and urban explorers still explore the town today, but it remains a dangerous area.

Individuals interested in some of the world’s “eternal flames” can learn more here.