In May 1962, a seemingly routine attempt to clear an unpermitted landfill in Centralia, Pennsylvania, triggered an underground inferno that continues to burn decades later. Council members hired firefighters to burn garbage in an abandoned strip mine pit, but flames swept through an unsealed opening in the rock face, igniting an underlying vein of high-grade anthracite coal. Anthracite, prized for its high carbon density and low moisture content, burns at extreme temperatures exceeding 900 degrees Celsius.
The combustion chemistry relies on a continuous supply of oxygen drawn through a labyrinth of old mining tunnels, natural fissures, and thermal-expansion cracks. As the coal pyrolyzes, volatile hydrocarbons and carbon monoxide are released, sustaining a self-propagating exothermic oxidation reaction. The fire moves along the steeply dipping Buck Mountain coal seam via thermo-mechanical fracturing: extreme underground heat bakes the surrounding sandstone and shale, causing the rock layer to collapse and creating fresh fissures that draw in atmospheric air like a chimney draft.
This chimney effect drives the fire deeper into the seam, rendering conventional surface quenching ineffective. Water sprayed onto the surface simply boils into steam or creates explosive carbon monoxide water-gas reactions underground, cementing Centralia as an ongoing subterranean chemical disaster.