The fire under Centralia has been burning since 1962. That spring, a dump in the Pennsylvania mining town caught on fire. The dump was in a strip mine, which led to an underground mine, which led to a coal seam under the town. Fire met fuel, miles and miles of fuel, so much fuel that firefighters have long since given up on extinguishing the fire.
The town of Centralia is pretty much empty now. It’s too dangerous: The ground is unstable, and sulfurous steam vents up from the underground fire. The post office discontinued Centralia’s zip code in 2002. These days, the town is a curiosity for roadtrippers—and a field site for scientists like Ashley Shade, a microbiologist at Michigan State University.
Shade studies how microbes evolve, in particular what happens when their homes are destroyed. When the fire started burning in Centralia, the once cool ground turned into unbearably hot dirt. Shade has recorded soil as hot as 120 degrees Fahrenheit near steam vents. “The soil remains hot for years, or multiple generations for microbes,” says Shade. As the fire depleted the coal seam underneath, the fire front moved, and some areas of the ground cooled down again.
When Shade and her lab made the trip down to Centralia two years ago, they made sure to sample soil on top of active fire fronts and former fronts. They took eight-inch-long PVC pipes, drove them into the ground with sledgehammers, and pulled up soil cores to take back to the lab. Then they sequenced the soil, taking a genetic snapshot of what microbes lived in the ground, which they share in a paper uploaded, though not yet peer-reviewed, to the preprint server PeerJ.