Peat Fires 101

Peat fires can burn up to 15 feet deep and are extremely difficult to extinguish. Russia, which has been plagued by peat fires this summer, constructed a 30-mile-long water pipeline from the Oka River to an area with peat fires east of Moscow.

The excerpt below is from a New York times article and is a quote from Guillermo Rein, an expert on smoldering subterranean fires and an assistant professor at the University of Edinburgh in Scotland.

Smoldering fires, the slow, low-temperature, flameless form of combustion, are an important phenomena in the Earth system, and the most persistent type of combustion. The most important fuels involved in smoldering fires are coal and peat. Once ignited, these fires are particularly difficult to extinguish despite extensive rains, weather changes or firefighting attempts, and can persist for long periods of time (months, years), spreading deep (5 meters) and over extensive areas of forest subsurface. Indeed, smoldering fires are the longest continuously burning fires on Earth. The Burning Mountain, a coal deposit in New South Wales, Australia, has been smoldering since 4,000 B.C.

The characteristic temperature, spread rate and heat released during smoldering are low compared to flaming fires. Smoldering peat fires creep at a speed of 1 meter per day. Whereas flaming fires result in superficial heating of the soil, smoldering leads to sterilization and loss of mass above 90 percent (a layer of 5 meters is reduced to 30 centimeters). Moreover, these fires are difficult to detect with current remote sensing methods because the chemistry is significantly different, their thermal signature is much smaller, and the smoke plume is much less buoyant than the emissions from flaming fires.

Smoldering fires can be ignited by natural causes such as wildfires, lightning strikes, self-heating or anthropogenic factors, e.g., slash and burn, arson, mining activities or waste incineration. The most typical scenario for peat fires is when a fast flaming wildfire sweeps over a region burning the surface vegetation and igniting the peat if this is dry enough. The peat then smolders for a much longer time. This is what happens in Indonesia and probably what has occurred in Russia this summer.

Water content of the peat governs smoldering ignition. The depth and the area affected in case of fire are also be dictated by the water content of the peat layers. The maximum water content for boreal peat to ignite has been measured to be 55 percent by weight. Any water content bellow this means the peat can smolder.

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About Bill Gabbert

Wildland fire has been a major part of Bill Gabbert’s life for several decades. After growing up in the south, he migrated to southern California where he lived for 20 years, working as a wildland firefighter. Later he took his affinity for firefighting to Indiana and eventually the Black Hills of South Dakota where he was the Fire Management Officer for a group of seven national parks. Today he is the creator and owner of WildfireToday.com and Sagacity Wildfire Services and serves as an expert witness in wildland fire. If you are interested in wildland fire, welcome… grab a cup of coffee and put your feet up. Google+

3 thoughts on “Peat Fires 101

  1. We battle them all the time here in NC. The Evans Road fire, a pocosin fire in eastern NC burned 43,000 acres in about two weeks, and then smoldered in peat deposits over 20 feet deep for the next 6 months. Generally, we have to bring in high-volume lift pumps to flood canals, and then stage pumps along the canals to feed an irrigation/sprinkler system. In places where widespread agricultural drainage systems exist, we try to reverse the flow of canals and flood the fire. It takes time, but it can be done. A type two team managed the water show I described above.

    • Hi Andrew B,

      I have been following the 2008 Evans Road fire in NC. It is an international case study. I am interested in more information if you have it.

      Anyone interested in more information on Smouldering Fires in the Earth System: I would be happy to send you a copy of the review paper that I am presenting in November at the VI International Conference on Forest Fire Research, Coimbra. Just send me an email to G.Rein(at)ed.ac.uk

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