Determining the causes of the fires could have huge financial implications in deciding who ultimately pays for the extensive damage, including almost 8,000 structures destroyed.
CALISTOGA, Calif. — On a blackened hillside across the road from Napa Valley’s prized vineyards, investigators have cordoned off driveways and posted round-the-clock security guards, forming a protective seal around what is believed to be the origin of the most destructive fire in California history.
“It’s a crime scene for us until we determine otherwise,” said Ron Eldridge, the deputy chief of law enforcement for Cal Fire, the agency leading the investigation. “Was there negligence or was there a violation of law? That’s ultimately what we are trying to determine.”
Among the thousands of wildfires recorded in California in recent years, most have been caused by human activity: sparks from rocks sliced by lawn mower blades; children playing with fire; arson; fireworks; welding torches; even satanic rituals.
For the state’s 160 full-time fire investigators, many of whom have been sent to the suspected points of origin of 17 fires in Northern California, the stakes have never been higher.
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Determining the causes of the fires could have huge financial implications in deciding who ultimately pays for the extensive damage, including almost 8,000 structures destroyed. Insurance companies will be looking to recover some of the more than $1 billion that the California insurance commissioner estimates they could end up paying out.
Eldridge, the Cal Fire deputy chief, says his officers are not favoring one theory over another.
They are interviewing witnesses and may call on experts, including metallurgists and arborists. Software that re-creates what an area looked like before the fire could also help in the search for the origin, he said.
“They have satellite imagery, they have aircraft, and they have boots on the ground,” said Andrea Buchanan, the chief deputy fire marshal for the city of Alexandria, Virginia, and a 37-year veteran of fire investigation. And, she added, they will probably need every tool they’ve got.
Experts who have studied the causes of wildfires in California say that it is too early to come to conclusions, but that the circumstances — nighttime ignition coupled with fierce winds — raise the possibility of power lines being involved.
“If there are high velocity winds, there’s every reason to suspect that power lines are a source,” said Jon E. Keeley, a fire expert with the U.S. Geological Survey in California. “We have many documented cases of power lines igniting fires during these high wind events.”
The utility company that runs power lines in the affected areas, Pacific Gas and Electric, said it was complying with a request from regulators to preserve all potential evidence.
The company trims or takes down 1.2 million trees near its power lines every year, a spokesman, Keith Stephens, said. California regulations require all branches within 4 feet of lines be removed.
Good fire investigators start on their bellies, looking at the tiniest things that burned — the blades of grass, said Jon Skinner, who oversees fire investigation and recovery for the federal Bureau of Land Management.
Grass-stem indicators, as they are called, can tell investigators a lot about the pace and direction of a fire and provide clues about where it began, Skinner said.
“If you have tall pieces of g
In the case of this month’s fires, investigators are treating the 17 suspected ignition points separately. But many of the fires merged, and it remains possible that embers from one fire could have started what are currently being classified as separate fires.