Home All 50 US States Tiny airborne sparks significantly contribute to wildfire propagation

Tiny airborne sparks significantly contribute to wildfire propagation

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While the cause of the recent devastating fires in Los Angeles remains undetermined, officials have identified one primary way in which the flames have spread: through embers.

Reports indicate that at least 24 fatalities have resulted from the fires, which have ravaged over 12,000 structures since commencing last Tuesday. The rapid spread of the fire has been exacerbated by strong winds that not only facilitate combustion by increasing oxygen levels but also transport embers to unburned regions.

Contrary to widespread belief, wildfires do not typically engulf homes through direct contact with racing flames. Instead, many residences are ignited by airborne embers that originate from the fire. Understanding embers and their critical role in wildfires is essential to mitigating damage.

An ember is essentially a fragment of burning material. Once it becomes airborne, it is often referred to as a firebrand, as explained by James Urban, an assistant professor at Worcester Polytechnic Institute’s Department of Fire Protection Engineering. “In the case of wildland fires, these are often comprised of burning pieces of wood or various forms of vegetation, but in urban areas, anything that combusts—homes, furniture, or other materials—can serve as embers,” he noted.

Embers can be as small as granules or as large as sizable chunks of burning debris. The capabilities of these embers are considerably different than everyday experiences with more benign campfire embers, according to Anne Cope, chief engineer at the Insurance Institute for Business & Home Safety. “These embers have the potential to travel several miles, and neighborhoods adjacent to wildlands frequently experience overwhelming showers of embers,” she remarked.

The wind plays a substantial role in embers’ effectiveness as an ignition source. Urban indicated that wind enables embers to burn with increased intensity and energy, forming firebrands that tend to congregate in areas like the spaces between wooden fences or in shrubs, eventually starting new fires.

A notable example occurred in 2017 when embers crossed a six-lane highway in Northern California, igniting businesses and spreading from one house to another in the Coffey Park area of Santa Rosa. Cope recounted a prevalent misconception at the time: “People thought that embers wouldn’t manage to cross such a considerable distance, dismissing the likelihood of ignition across the interstate. The term ‘never’ can be perilously misleading.”

While a single ember might extinguish itself in a matter of minutes, it could also linger and smolder. Urban explained, “Under certain conditions, like a sudden gust of wind, they can reignite and lead to widespread destruction.”

Researchers are currently investigating embers through collaborative initiatives, including the Wildfire Interdisciplinary Research Center, a partnership with San José State University and support from the U.S. Forest Service and National Science Foundation. Urban highlighted that they are studying how firebrands form and how this understanding can inform wildfire spread models and effective defensive strategies for homes. His students have been conducting experiments on how vegetation management around buildings influences the rate of fire spread between structures.

Urban expressed optimism about the ongoing research endeavor, emphasizing the necessity for improved preparedness for future fires. “We’re likely to encounter more wildfires like this in the future, and it’s imperative we adapt our approaches,” he stated.

Cope echoed this sentiment, asserting, “I would be thrilled to see a more strategic integration of wildfire ember preparedness into numerous areas where it’s currently lacking.”

@USLive

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