Geology Reference
In-Depth Information
1.2. Origin of Coal Fires
Sinkholes such as this one due to an
underground mine fire in Renton, Pennsyl-
vania may develop without warning,
resulting in injury or death.
Photo: US Bureau of Mines, 1985.
Introduction
C
oal fires in abandoned mines, in waste banks, and in unmined outcrops constitute serious safety and environ-
mental hazards. Subsidence, the emission of toxic fumes, and deterioration in air quality create an unsafe and
unpleasant atmosphere that can consume resources and depress property values for affected land and for adjacent
areas. Fires in abandoned mines and waste banks often affect people who had no connection with the original
mining.
Coal fires occur in almost every coal-bearing area and have been a problem for hundreds of years. In 1765,
a fire was started in the Pittsburgh seam in Pennsylvania. This fire was active until at least 1846 (Eavenson, 1938,
1942). In the Western United States, coal-outcrop fires were a natural feature of the landscape. In 1805,
Lewis and Clark, in their exploration of the Missouri River, reported that coal seams were plainly visible in
the bluffs along the river and that some of the veins were burning, ignited by spontaneous combustion or by grass
fires (Lavender, 1988, pp. 190, 196). In southeastern Montana, an outcrop fire in a 6m (~20 ft) thick seam has
propagated ~1524m (5000 ft) along a small drainage basin. The fire has affected a total area of 500 acres and has
been burning for an estimated 400
600 years (Shellenberger and Donner, 1979). Hundreds of natural coal-bed
fires are burning in the PRB. The age of zircons in associated clinker indicates that such fires have been occurring
in this area for thousands of years (Heffren et al., 2007). Coal fires associated with the abandoned or inactive coal
mines are reported from mining areas around the world (Prakash and Gupta, 1999; Stracher and Taylor, 2004).
Surface expressions of underground coal fires observable in the field include baked rocks, areas of dead
vegetation, land subsidence, and gas vents and fissures with encrusted minerals (Gupta and Prakash, 1998;
Stracher, 2007).
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