It’s a job that requires a detective-like curiosity and a puzzle aficionado’s ability to suss out visual patterns.
Like an archeologist sifting through ancient ruins, you also have to be prepared to get on your hands and knees.
As dozens of firefighters from Quebec and New Brunswick arrived in British Columbia on Monday to help battle nearly 200 active wildfires burning throughout the province, investigators in the village of Lytton — which was devastated by a fast-moving, wind-whipped fire last week — are beginning the slow, methodical process of scanning the charred landscape to try to determine the cause of the blaze that killed at least two people.
Officials with the B.C. Wildfire Service have said the Lytton Creek fire was likely “human-caused,” a broad term that basically means anything not caused by lightning. Some area residents have suggested sparks from a train could have caused the fire, but those reports have not been verified. The RCMP is the lead investigating agency; it is getting help from the B.C. Wildfire Service.
Wildfire investigators not connected to the case told the Star on Monday that the job of pinpointing the origins of a fire requires keen observational skills and a skeptical mind to avoid arriving at conclusions too soon.
Above all else, they said, it requires patience.
Investigators typically start with gathering accounts from eyewitnesses — including first responders and civilians. Do they have any photos or video that could give an approximation of where the fire started?
Once investigators have identified a “general origin area,” which might be about one-quarter of a hectare, they’ll rope it off and then start doing a visual search for “fire-direction indicators” — clues in the landscape that indicate the direction the fire moved.
There’s an important distinction between investigating a wildfire and a structure fire, said Paul Steensland, an Oregon-based wildfire investigation consultant and former senior special agent with the U.S. Forest Service.
With structure fires, the point of origin is usually found where there’s the most damage. Because it’s a confined space, heat builds up and stays the longest where the fire started.
Wildfires, however, burn in unconfined spaces, propelled by wind, fuel and slope. As a result, the heat dissipates rapidly, and that’s why there’s typically not a lot of damage at the point of origin.
Wildfires travel in multiple directions. There’s the main, flaming front of a fire. That’s the most intense. Then there are less intense flames that branch off from the main fire at 45- to-90-degree angles, known as flanks. On the backside, there may also be flames moving in the opposite direction of the main fire; they have the least intensity.
One of the clues to a fire’s nature can be found in the grass.
Grass stems in the path of the main, advancing front will get chewed up from the top down, leaving behind just a little stub of stem close to the ground.
In the back zone of a fire, grass stems will be burned at their base and fall over into the area already burned, but the lack of residual heat means the grass stem remains mostly intact.
These differences in vegetation can help investigators start to home in on where the fire may have started.
Investigators can also determine the path of a fire from examining rocks on the ground. Vapourized oils or resins in the flame and smoke stick to surfaces, staining rocks yellow or brown, said Ken Ness, a wildfire investigation consultant in Saskatchewan and former detective-sergeant with the Saskatchewan Conservation Officer Service.
The side of the rock that is heavily sooted obviously was exposed to the fire and indicates the direction the fire came from.
And there are more visual clues.
Picture a pine or oak tree. As the flames reach the tree, the heat softens the foliage. The wind driving the flames will push the foliage in the direction of the wind. As the fire moves on, the foliage dries out and freezes in place — pointing in the direction of the fire.
“It’s always a reliable indicator of wind direction,” Steensland said.
Relatedly, as a fire approaches a tree, it “comes in low” at the base and then “goes out high” at the crown, causing most of the damage on the back side of the tree, leaving behind what’s known as an “angle of char.”
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“A lot of times, we see that flying in a helicopter,” Ness said.
Investigators will place coloured flags over the general origin area — red representing the fire’s main front, yellow representing the lateral flanks and blue representing the back side.
“Once those are all in place, you can look back over your shoulder and absolutely see the fire progression — it’s a beautiful tool,” Steensland said.
Eventually, investigators will home in on a “specific origin area” — an area of roughly three metres by three metres, where they think the fire started.
Sometimes, the ignition source is in plain sight — an abandoned campfire, a burning barrel or burnt piece of equipment.
Other times, it requires getting on all fours and doing a grid search.
What exactly are they looking for?
Steensland said one of his mentors once described it as akin to “looking for something that is usually quite small, quite black and in the middle of a whole bunch of other black stuff.”
“What you’re trained to look for is something that doesn’t look like it belongs there. That could be a shape, it could be a texture, it could be a colour,” he said.
“Investigators will get down on their hands and knees, set up grid lanes like it was an archeological dig. And that will be searched meticulously with the naked eye, with magnification, with metal detectors or magnets.”
The work is tedious, but it has to be done, Ness said.
Sometimes, investigators will luck out and find matches or pieces of hot metal or a catalytic converter or remnants from fireworks.
Asked about the notion that train sparks could have caused the blaze, Steensland said it’s possible though not as common as in the past due to advances in train technology.
In the past, cast-iron brakes were common on trains and notorious firestarters, he said. Most rail companies have moved to composite braking systems. If there were sparks from braking, it’s likely because the padding had worn down.
In a previous statement to media outlets, CN Rail said: “We want to offer our support to the people of Lytton and we are committed to assisting this community during this tragic event. CN is co-operating fully and will provide all information that may assist with the investigation.”
John Stefaniuk, an environmental lawyer in Manitoba, said people need to “exercise appropriate caution” because anyone can be found liable for starting a wildfire.
In British Columbia, a person or company could be found liable if they fail to keep a fire from escaping their property, if they contravene a regulation that is in place to stop wildfires or if they intentionally, or recklessly, do damage to land by starting a fire.
Those found liable can be made to pay for land damage and firefighting costs, he said. In the most egregious cases, where someone intentionally starts a fire, a fine of $1 million and jail time could be sought, Stefaniuk said.
Stefaniuk also pointed to a case where CN Rail had to pay more than $16 million when workers cutting railway lines ignited a wildfire in British Columbia in 2015.
“British Columbia and Alberta, in the last number of years, have become a little more aggressive in pursuing contraventions of the legislation.”
With files from The Canadian Press
Douglas Quan is a Vancouver-based reporter for the Star. Follow him on Twitter: @dougquan
Kieran Leavitt is an Edmonton-based political reporter for the Toronto Star. Follow him on Twitter: @kieranleavitt
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