Seismic investigation of natural coal fires: A pre-fieldwork synthetic feasibility study.

Abstract:

Natural underground coal fires are a world-wide concern, emitting carbon dioxide and other pollutant gasses into the atmosphere; one such coal fire is located at Durango, Colorado. We carried out elastic modeling in order to investigate the potential of applying P-wave seismic methods to the problem of differentiating between burned and unburned coal in the upper $\sim$30 m of the subsurface at the site near Durango. This is a challenging problem for any geophysical method, but preliminary modeling results show that the problem is tractable under certain circumstances. Our highly simplified model suggests that imaging the coal layer can potentially be accomplished with adequately high frequencies (source center frequency $>$ 125 Hz); imaging the actual burned zone would be more difficult. The model neglects the major near-surface heterogeneity known to exist at the site; features such as fissures would surely result in diffractions and reflections that could obscure much of the desired signal.

Seismic investigation of natural coal fires: A pre-fieldwork synthetic feasibility study.