"Some houses that did not burn were actually protected by just a scratch line—that is, just a raked line to bare dirt, around the house…"
…well, the fire that went through Los Alamos, when it actually got to the city, was a surface fire, but it was burning on the ground. It was not raging, at that point, through the crowns of the trees, through the treetops. It actually came into town as a surface fire, and some houses that did not burn were actually protected by just a scratch line—that is, just a raked line to bare dirt, around the house. And that's why the house didn't light up. Basically saying that no protection of your house is the main reason why it went up in the Sierra Grande Fire—but the lack of any protection is what caused them to burn, and that anything at all, even these scratch lines in some cases, were enough to keep the house from burning. So the first place to start is by protecting the houses.