Coal fires as a natural hazard exist in many places where coal
is available in a specific amount. They can occur either within
the coal seams themselves or in stock piles and overburden dumps
on the surface. These are remains from mining excavations and
have a high content of carbon.
There are more and larger burning areas originated by coal fires
than the public may imagine. As a natural hazard they can occur
in many places where coal is available in a greater amount. Especially
in coal producing countries such as China, India, Indonesia and
other developing countries, underground and surface coal fires
are a serious and widespread problem. In China's
coalfields, where we have made much effort to detect, measure
and monitor underground coal fires, fires are spread over the
northern part of the country.
Coal fires have not only been a problem since the start of coal
mining. We have gathered geological evidence that some fires were
burning several hundred thousand years ago. It is believed, however,
that their number has increased continuously since the beginning
of extensive coal exploration. The factors
causing coal fires are manifold, but they all can be attributed
to the coals ability to react with oxygen. Spontaneous
combustion is thereby one of the main coal fire causes.
However, during the past, little attention was paid to the serious
economic and environmental problems that are involved with
coal fires. A reason for the ignorance can be found in underestimation
of the hazards both at national and international level. Today
coal fires are mainly under control in developed countries, but
effective techniques for fire fighting
are missing in newly industrializing countries.