Muck fires result when the loose, organic material found below the top layer of soil ignites and produces a sub-surface fire that can burn for weeks and reach temperatures of more than 500 degrees Fahrenheit. In addition to being difficult to extinguish, muck fires can produce noxious fumes and spread destructive heat to tree roots, causing trees to topple. The heat generated by a muck fire can also transfer underground horizontally to neighboring areas and ignite forest fires yards away from the original subsurface fire.
The organic material that feeds a muck fire, also known as peat, is used as fuel for cooking and heating in many places across the world. Ireland, Finland and Russia use their peat deposits to generate electricity in power plants.
Comprised of decaying subsurface vegetable matter and containing a high concentration of carbon, peat burns with a higher carbon dioxide emission than natural gas or coal. It also burns easily in low moisture conditions and, while still below the surface, can be ignited by a spark from an above-surface fire or through a lightning strike.
Once ignited, smoldering peat fires can burn for weeks or months before they are detected. In the United States, muck fires, as they are commonly called, can occur during periods of drought. They can grow into significant threats to health and property in areas of high peat concentration, such as those found in the subtropical regions of Florida.