EVIDENCE FOR MULTIPLE COAL BEDS ON FIRE IN CENTRALIA, PA

Thermal infrared imagery and fracture patterns related to mine subsidence reveal both the Buck Mountain coal bed (No. 5) and the Seven-Foot coal bed (No. 6), and possibly the Skidmore Leader coal bed, are on fire in Centralia, PA. The fire ignited in 1962 and has been burning for nearly 50 years. Since that time, numerous reports have suggested that the Buck Mountain coal bed, from the Llewellyn Formation (Pennsylvanian), was the only bed on fire. Aerial thermal infrared images reveal two linear trends of heat released at the surface. Superimposed over a geologic map, the linear trends coincide with the coal beds. The linear trends also coincide with the locations of two parallel, linear trends of sinkholes related to mine subsidence and the current gas/heat vents from the fire. Recent high amounts of precipitation in Centralia have resulted in the increased development of two sets of parallel mine subsidence depressions. Increased moisture from this precipitation, released as steam at the vents, has weakened the overlying bedrock, forcing collapse. The east-west sinkhole orientations, correspond to the trend of the heat release identified using thermal infrared imagery. Additionally, measurements from gas vents indicate slightly lower O₂ and higher CO₂ values for the deeper Buck Mountain coal bed in comparison to the Seven Foot coal bed. Sinkhole orientation, thermal infrared patterns, and gas concentrations suggest that multiple beds of anthracite coal are burning in the subsurface.