When a fast-moving, erratic wildfire ignites, firefighters right away try to save homes and steer the flames away from life and property. But experts say the real danger often occurs in the hours after the big wall of flames rips through.
That's how the home of Rodrigo Moraga, a volunteer firefighter in Colorado, caught on fire. In 2010, he was one of the first responders to a wildfire racing through a tinder-dry canyon outside Boulder. As the main flanks of that fire moved on toward a small town, he ordered all available engines to follow it. Several hours later, he stood on a ridge above his own house. He noticed a small spot fire slowly starting to burn toward some pine needles in his backyard.
"So I watched the fire get closer and closer to my house and I kept calling for engines, but I had actually assigned them to other places, so I had no more engines," he says.
He watched as that little fire in those pine needles jumped to his wooden deck and then the house. And then he watched his home burn to the ground. The lesson here? "It's the embers after the main front that start the house fires," Moraga says.
In other words, that big wall of flames that captures everyone's attention on TV is usually not what causes all the destruction.
"Obviously the cameras always go to the big flames, and so they typically will show big flames and then they'll show a house burning," he says. "You tend to connect those two and say 'Oh, that big flame burned that house.' "
But research shows that's not always the case. Fire behavior analysts with the U.S. Forest Service studied that 2010 Colorado fire. They found that more than three-quarters of all the homes destroyed burned several hours after that initial flank of flames came through. For Jack Cohen, a coauthor of the study, this is a wake-up call for how more homes can be saved from wildfires.
"They're not vulnerable because they suddenly burst into flames in full involvement," he says. "It's because nobody's there, and the reason nobody's there is because there are many more houses than there are resources to address the ignitions."
Cohen says there are things people should be doing before a fire to make their houses as ignitionproof as possible: clearing all the pine needles from gutters, adding fire-resistant siding and roofing. And, he says, fighting an erratic, dangerous wildfire shouldn't be about trying to control it.
"It's to understand how homes ignite and to use that to our advantage," Cohen says.
There's also a growing thought that firefighting tactics need to change, especially during those initial hours. You often have large, type 1 engines, like you'd see on a city street, trying to drive up into mountain neighborhoods while evacuees are trying to get out. Cohen says you're better off scattering smaller crews around an area whenever possible.
"Lots of people around to find the ignitions with a little bit of water," he says.
None of this is much comfort to the hundreds of Californians right now who are enduring the hardship of losing everything in a wildfire. But fire behavior experts say these modern wildfires are becoming more and more like hurricanes or tornadoes. We'll never stop them, but we can learn to live with them.