The California Wildfires: How Experts Track a Blaze to Its Origin
By Kirk Johnson
PARADISE, Calif. — One huge fire was caused by a spark set off by a man with a hammer, working on a fence post in a field of dry vegetation. Another began at a backyard barbecue. A 2007 fire on Santa Catalina Island was ignited by workers cutting metal wires with a torch.
As investigators try to determine what started the most devastating wildfire in California history, which killed at least 56 people, the beginning premise is that human beings — through their mistakes, or their toys, tools and technologies — were probably behind it.
But looking into the cause of a fire, which can take months of painstaking work, also means rolling back the clock to a moment and to a spot that, like most of the town of Paradise, has been reduced to ash. What was there at the moment of the fire’s birth was probably destroyed by the fire itself, or at least profoundly altered.
Even a tiny pebble can be an important clue. On which side was it blackened by heat? What’s the condition of the soil below the fire at the place it started? An electrical charge from a high-voltage power line, for example, can solidify sand with a telltale signature. Then investigators look at things that were touched by the flames but not destroyed.
“If you’re looking at some trees, you look at the angle of char, the way that the needles froze in the heat; then you can say, ‘This fire spread from right to left,’” said James Engel, the deputy chief of law enforcement and fire prevention at the northern division of California Department of Forestry and Fire Protection, better known as Cal Fire.
The so-called Camp Fire, which, in addition to its death toll, destroyed more than 10,000 homes and businesses, began on a day of low humidity, strong winds and lingering drought, with soils and plants in some areas parched by more than 200 days with no significant precipitation. That was the environment in which the fire began — itself a crucial piece of the puzzle.
An electrical cause is certainly on the table, Mr. Engel said, from a power line that could have fallen in the wind, or some other malfunctioning electrical equipment.
[A ‘perfectly imperfect’ life: The victims of the California wildfires.]
Other causes will also be considered, from a tossed cigarette to a power-mower blade sparking a rock to a hot vehicle tailpipe. Many investors in Pacific Gas and Electric, one of California’s largest utility companies, have already placed their bets and reduced their risk, with the company’s share price plummeting in a wave of selling in fear that the company will be held liable.
The utility was responsible for several of last year’s wildfires that burned through Northern California’s wine country. In fact, Cal Fire has determined that of the 21 major fires last fall in Northern California, at least 17 were caused by power lines, poles and other equipment owned by Pacific Gas and Electric Company.
Earlier this year, the utility said that it would begin pre-emptively turning off the power to some customers to avoid causing wildfires under certain conditions.
Cal Fire, once it determines a cause, can seek compensation for firefighting costs — which in the case of the Camp Fire will be staggering, whoever foots the bill. More than 5,600 firefighters were still on the lines on Wednesday, with 23 helicopters in the air and 630 fire engines were on the ground. The fire has burned 138,000 acres and was 35 percent contained.
Whatever triggered the blaze — which was first reported early Thursday, just east of Paradise, a town of about 27,000 people in the Sierra Nevada foothills — strong winds roaring through the dry terrain were the reason it spread so quickly and caused so much devastation.
A changing climate is potentially part of the Camp Fire’s story, in deepening patterns of drought in California. Some researchers said that logging in the burned area after a fire in 2008, which was intended to clear out fuels and make this part of Northern California safer, may have had the opposite result. The logging may have left fast-burning weeds and young trees in the fire’s path.
“When it got to the logged area, it spread very rapidly and people just didn’t have much time to evacuate in Paradise, so this whole notion that logging — so-called hazardous fuels reduction — was going to save the town is a dangerous falsehood,” said Chad Hanson, a fire ecologist at the John Muir Project, an environmental group that has been critical of land-management policies and logging practices on public lands. The speed at which the fire spread has raised concerns about the nearly 100 people who are still missing.
For the team of 10 investigators from Cal Fire that has begun its work, old-fashioned shoe-leather will be the start. They plan to interview as many witnesses as possible, and Mr. Engel said he starts every day looking in the news media for the names of displaced fire survivors.
In the age of the cellphone, another important investigative tool will be video. Many people turned on their phone cameras as they were escaping or as the fire was approaching their homes, and posted the video to social media. Investigators will be searching for the video, hoping to create a kind of composite from multiple sources, showing how the fire spread and which way smoke was moving at any given moment.
The investigation of the Camp Fire will not end with the state’s inquiry. Private investigators, especially from insurance companies, will eventually arrive, though Cal Fire’s work comes first. If criminal charges become part of the picture, prosecutors from Butte County or other jurisdictions also would be brought in.
Mr. Engel, the state fire official, said that investigators do not typically focus on the broader issues of land management or climate science: how and when trees were cut for timber, for example, or patterns of drought.
Those things could be important in a fire’s total impact, he said, and on the potential for more fires. But determining the cause of a fire is like taking a short story that is complete except for its first sentence, and then writing a beginning that explains how and what happened.
That sentence often starts with something about the weather. “Temperature, wind and humidity; those are the things that affect ignitions,” Mr. Engel said. After that, human variables are almost always in play.
Researchers have shown, for example, that when people take their guns out into the woods for target practice, some kinds of ammunition are more likely to start a fire than others.
“As a fire flows, it hits objects that it consumes, or may not consume, and it leaves indicators on those objects,” Mr. Engel said. “That’s where we start reading.”
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