Coal fires are reported from nearly all parts of the world where coal reserves are present (see global distribution). However, the occurrence of such fires is far more common in areas where the coal is/was actively mined. So is this hazard truly natural or man made?
Naturally occurring coal, under favourable conditions, has a tendency to burn spontaneously, and to continue burning for years unless the conditions change or are controlled by human intervention. Sunlight falling on coal seams, oxygen from air and presence of some moisture may be sufficient to start the coal to burn spontaneously. In this sense the coal fires are a natural hazard. Research shows that naturally occurring coal fires can be dated back to the Pleistocene times.
In areas of active and abandoned mines, mining activities result in breaking/crushing of coal and spreading small fragments of coal, carbonaceous material and coal dust in the vicinity of the main coal seam. This porous coal rubble is much more prone to spontaneous combustion than a thick coal seam would be. The coal dust catches fire, which then spreads to the neighbouring coal seam. Though the coal dust may ingnite by spontaneous combustion and the fire may so be classified as one occurring from natural causes, the problem is certainly initiated and aggravated by human influence. In this sense coal fires fall under man made hazards.
Additionally, frictional energy from mining machines and negligent acts of mine workers can also trigger coal fires. The mine openings, goafs (empty spaces in underground mines where coal has been already extracted), bore holes, cracks etc. all provide additional vents and spcaes for supply and circulation of oxygen, further aggravating the problem. Finally the reason for the start of the fire becomes a secondary issue. The most important thing is that once the coal seam catches fire the problem gets more and more difficult to tackle.
Ironically, till recently, such a major environmental hazard was overlooked or largely undermined by the international community. Some reasons that can be attributed to the rather low levels of concern are:
