Northern California's Carr Fire

    The Carr Forest Fire that occurred over the summer in Northern California was, as the name cleverly suggests, sparked due to an automotive accident. It’s suspected that a towed trailer with a burst tire initiated the blaze when the rim of the wheel scraped against the pavement, throwing up sparks until eventually one happened to land upon suitable fuel.

    From that point the fire quickly grew along with several others in the north of the state at the time. The greater fire complex became the largest in the state’s history well before it was reduced to a controlled state. Even now there are fires which continue to rage in Northern California that are separate from the fires of August but pose problems nonetheless.

    The reason that current fires exist in such close proximity to the fires only a month ago is due to the same factors which allowed the initial blazes to grow so quickly. These factors are primarily different forms of weather. One of the most obvious is the ongoing drought in much of California and naturally such a situation is always more prone to fire.
    A perhaps more important factor in this lies in the winds. While dry trees can burn like kindling, the rate at which the fire actually spreads is often dictated by the wind for two reasons. The first of these is strengthening the fire. Strong wind acts like a bellows upon a fireplace, bringing in more oxygen to feed the flames. The second primary factor is that the wind helps spread the embers. Traditional firebreaks operate on a simple principle, create a strip of land with no flammable material on it so the fire cannot spread past it. For forest fires without strong wind this can be an incredibly effective measure as the drifting embers tossed up by the fire are less likely to float over a fire break. With strong wind however, the embers can be easily carried over most firebreaks to ignite a new part of the fire on the other side.
 

    Beyond this there exist other factors such as ambient heat, difficulty of the terrain, and fuel availability. Somewhat surprisingly the former plays a much smaller roll in the spread of wild fires than many weather conditions. While a greater amount of material to burn does allow for larger fires, it doesn't facilitate growth to nearly the same degree that strong winds do.
     So far most of the elements discussed have been natural ones, aspects outside of the control of humans and as a result fitting of the term 'geohazard.' Of course that isn't to say that wild fire or other geohazards are without human fault. In the case of the Carr Fire the most obvious human error comes from the flat tire which sparked the inferno. Beyond this the greater fire complex suffered from other issues such as towns and cities developing housing in previously undeveloped areas that were a risk. While the property damage ended up less than it could have been, the fires still displaced tens of thousands of people and killed several.



Sources:
Northern California wildfires now largest in state history and growing. Chicago Tribune; Associated Press. August 7th, 2018
Found here

Bessie, W.C. The relative importance of fuels and weather on fire behavior in subalpine forests. Ecology 76(3):747; Wiley. 1995
Found here

Photos sourced from:
Curbed
Mashable