How Houses Themselves Become Fuel For Wildfires

作者:未知 来源:美国国家公共电台 2018-12-26


This year, California saw the most destructive wildfire season in its history. Take last month's Camp Fire in Northern California, which decimated more than 18,000 structures, many of them homes in the town of Paradise. It's bringing attention to the emerging science around how and when homes burn during wildfires, and that science is not what you might expect. NPR's Kirk Siegler explains.

KIRK SIEGLER, BYLINE: When firefighter and Malibu Town Councilman Rick Mullen got the call last month for the Woolsey Fire, he set in motion a plan his family had long practiced. While he and his crew mobilized to the front lines, his son stayed home and defended their house, even though they were under evacuation orders.

RICK MULLEN: He and a couple buddies executed the plan we've been training on for years and did a great job.

SIEGLER: We talked as Mullen drove through a burned-out Malibu neighborhood. At his house, it was a small crew who knew what to do, didn't panic and stuck to the plan. They had supplies to survive for days. They had well water they could pump. And they kept an eye on embers landing on the roof or near the house or deck and douse them. And their home - it survived.

MULLEN: It can be visually terrifying. And if you don't understand fire behavior, that can be panic inducing. The reality is, even though it looks bad, you're in a very survivable position.

SIEGLER: There are stories like this in Malibu and even Paradise. Hundreds of homes were destroyed, but hundreds were spared, and some likely due to the fact that there was just somebody there watching over it with a hose.

MULLEN: After that big fire front comes through, since there's nobody around, a lot of these homes can burn down.

SIEGLER: What he's saying right there is key. It's long been a misperception that most homes burn when that initial big, dramatic wall of flames from the fire blows through. But the science shows most homes actually tend to burn long after this, sometimes even a day or more later.

JACK COHEN: We tend to pay attention to the flames, and that's not the biggest part of the problem.

SIEGLER: The biggest problem is often the stray ember after the main fire that lands on some pine needles in a gutter or an outdoor furniture cushion. Jack Cohen is a wildfire behavior scientist who pioneered this home ignition research for the U.S. Forest Service.

COHEN: If the homeowner is present, then a little bit of water is quite effective in putting that smoldering combustion out.

SIEGLER: Now, Cohen isn't encouraging people to defy sheriff's orders and stay behind to protect their home, but he is trying to get a conversation going about this new fire reality. They may begin as forest fires, but they're turning into urban structure fires, jumping from one house to the next.

COHEN: Why would we stay at the house? Well, the bottom line there is that a house that doesn't ignite and burn is the safest place to be.

SIEGLER: A house that doesn't ignite, like one with fiberglass shingles, vents that embers can't squeeze through, that may may be a safer place to be than getting stuck on a road while thousands of people try to evacuate. Right now, public officials like Rick Mullen in Malibu don't have the data that would allow them to identify homes or neighborhoods where people could safely shelter in place.

MULLEN: I'm not going to encourage anybody to stick around. OK? I accept the reality that some people do that. But that's the biggest responsibility for public safety professionals is to save people's lives.

SIEGLER: Still, fire managers are keenly interested in this idea of creating more so-called stay-and-defend communities. Scientist Jack Cohen says this doesn't mean a neighborhood full of homes made of concrete.

COHEN: We don't necessarily need to build ammo bunkers to live in in order to deal with this.

SIEGLER: Instead, he says it's often just those little things left unattended that have the biggest consequences. It's the stuff right by the house, what he calls the home ignition zone - the debris in the gutter, the dried-out hibiscus hanging in a planter.

COHEN: We're fighting, really, against a culture and a perception of how the ignitions occur.

SIEGLER: Cohen says we need to stop fighting these megafires like forest fires, and instead, build or redesign neighborhoods that are more resistant to the urban fires these have become. Kirk Siegler, NPR News, Los Angeles.






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