Eli5: how do fire detectives find the start of a large fire? Is it more burnt in that specific area where it started somehow?
In: Chemistry
Planning something??? Lol.
> is it more burnt
That’s a big part of it. If you’re investigating a house fire and you can see that the end of the house where the garage is has been almost completely burned away but the bedroom end is intact, there’s a very good chance that the fire didn’t start in the bedroom. So then you can start investigating what’s left of the garage for an ignition source.
Same thing with brush fires. If you’ve got a huge field that burned, absent any wind or changes in fuel density, the origin point will be near the middle of the burned area. If there is wind, you can guess where the origin is based on wind speed and direction.
Fire investigators are required to have a vast array of knowledge on fire dynamics, including how specific objects and fuels burn and what pattern a fire would likely take in a specific environment given the fuel.
Using that information, an investigator can usually determine whether a fire burned in a way it shouldn’t have been able to (perhaps indicating a fuel or accelerant like gasoline had been used) or whether the fire originated in a location with no obvious ignition sources.
Fire investigators also have tools/instruments that can detect unburned accelerants that may have been used.
I heard on Joe Rogan arsan experts are full of shit. Anyone care to explain?
One time after we put out a wildfire a more experienced firefighter pointed out several signs to me that a small fire in the woods was set intentionally. It was in close proximity to a main road but far enough away that it wasn’t from a chain spark or something and had started at the bottom of a slope, allowing the fire to “run” uphill. Searching around the bottom area he found scraps of fabric that could have been soaked in gasoline to accelerate the process. There were small signs that I would have never caught and were so clear to him, and he wasn’t even a fire investigator.
They will also do things like cut the burned studs. They can see which side has more damage and determine direction of the flames. Had a friend study it and his textbooks were very interesting.
I always wondered how they could figure out that it was a cigarette that started a fire. That’s next level.
Also interviews with first responders and witnesses. First firetrucks on scene, how fire spread from room to room. Was it in the attic, basement, etc.
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