What causes fire embers to spread more quickly
There are ways to protect homes from wayward embers that could threaten them.
One of the most dangerous factors in the spread of wildfires comes from the fire itself, as small embers sometimes travel up to miles ahead of the fire with the wind and threaten to ignite new fires all over.
Researchers at the University of California Irvine who study the behavior of fire embers have determined the majority of fire damage in major wildfires comes from embers that have the ability to move far away from the actual burn site. They also have studied how strong wind gusts can send even large embers flying long distances where they can land and create new spot fires.
"We are trying to understand under what conditions the embers are lofted away from the fire," Tirtha Banerjee, associate professor of civil and environmental engineering at U.C. Irvine, told ABC News. "So, how fast do they emerge? How many of these embers can emerge and how far they can really land?"
That data could improve fire forecasts, allowing city planners, firefighters and homeowners to better protect themselves.
The types of plants situated around a home could determine the likelihood of whether a fire could reach and ignite the structure, experts said.
Invasive grass played a huge role in the rapid spread of the Maui wildfires that broke out in August, officials said. Invasive species also snake through the mountains in Southern California, escalating the spread of wildfires in a region prone to dry landscapes and high winds.
ABC News Chief Meteorologist and Chief Climate Correspondent Ginger Zee conducted an experiment in which a propane torch started a fire in a small pan filled with a small amount of ligher fuel. That simulated ember started at three different sites: one solely with invasive grasses; a pile with a mix of invasive and native plants, such as white sage, which can hold more moisture; and one pile with only native shrubs.
The invasive grasses spread more quickly, while the white sage in the second pile temporarily stopped the invasive grasses from igniting further and spreading. In the pile with only native shrubs, flames continued burning at the ignition site, but the plants did not catch fire.
While any plants can burn, native shrubs and trees act like a defensive barrier, giving residents critical extra minutes to escape if fires approach too closely, experts said.
Although palm trees have become synonymous with the Southern California landscape, they are not native to the region and when dry also have the ability to spread fires, Cassy Aoyagi, president of FormLA Landscaping, a landscaping company that specializes in fire protection, told ABC News.
"They light up like tiki torches and embers fly off them right onto roofs and structures and spark new fires," she said.
There are ways to design landscapes to make homes more fire-resistant and prevent embers from igniting, Aoyagi said.
Homeowners should leave 5 feet of gravel or concrete as a buffer around the house, Aoyagi said, adding that wide open spaces are "not the way to go."
"In the case of wildfire, where embers are flying in, it actually creates ember bowling alleys that just invite embers to roll in all the way to the home," she said.
While there should be a "zone zero" around the house, essentially an ember-free zone where there is nothing that can catch fire, native plants outside of that can serve as linebackers, protecting the structure from embers that may fly that way.
"Ideally, the strategy is that the ember lands into a hydrated green plant, and that it loses its fuel before it attaches to something that's combustible on the house," Aoyagi said.
Garden centers often sell invasive grasses as ornamental plants, so it is especially important to research plants before purchasing them for your yard, Aoyagi said.
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