As fires raging across Southern California amid lines, bridges and airports, the news has been filled with reports of a lack of containment and communities under evacuation warnings and orders.
But what exactly does all this mean? Here's a quick guide to many of the terms public safety officials use to describe the spread of wildfires, efforts to stop them and steps taken to protect residents.
Percentage content: In the world of firefighting, containment means a certain level of control — specifically, how much of the fire's edge or perimeter firefighters believe they can prevent from spreading. A natural barrier like a river or stream can help. Human interventions, such as using a bulldozer to scrape vegetation off a strip of land and deprive the fire of the fuel it could use to grow, can also help.
So even when a fire is 100% contained, it can still blacken acres of land and firefighters can continue to fight to keep it from getting out of control. The percentage is simply what firefighters tell the public how much of the fire perimeter they believe will not go beyond their defenses.
One X factor is wind. Unlike fires that grow based on topography or follow the path of the fuel they're burning, extreme wind-driven fires are notoriously difficult to contain until the winds die down.
Contingency line. Firefighters typically set up layers of defense called contingency lines some distance from the fire perimeter. They clear the ground down to the dirt on ridge tops up to a mile from the fire edge to establish a position for possible future defense. Meanwhile, they move closer to the fire, laying down lines of fire retardant and using bulldozers, shovels, axes and chainsaws to clear vegetation.
Revised. After reaching 100% containment, which can take months depending on weather conditions, the size of the fire and the topography of the area, crews work to declare the fire controlled.
Once a fire is under control, it is virtually out. Authorities will no longer assign crews to the fire and instead send out a patrol every day to make sure no burned areas reignite and cause another fire.
Evacuation order. This is a legal order for immediate evacuation arising from an imminent threat to life. An area subject to an evacuation order is closed to public access and people who defy the order can be charged with a misdemeanor, in addition to being caught in traffic along the escape route.
Evacuation warning. If an evacuation order means “go,” an evacuation warning is the equivalent of “get ready.” It indicates that an area faces a potential threat to life and property, so people there should be ready to leave at a moment’s notice. People who need more time to evacuate, such as those with limited mobility or who have pets or livestock, should evacuate immediately.
Shelter in place. This order means it is risky to be outdoors, but safe to remain on your property. The California Governor's Office of Emergency Services says that when a shelter-in-place order is issued, people should remain indoors, with doors and windows closed and locked, until further notice.
News reports may also mention several different types of firefighting equipment.
TO hand crew Build fire containment lines using chainsaws and other hand tools, as well as burning out areas with devices such as drip torches, a device that is a combination between a lighter and a flamethrower. These crews also perform mopping and clearing work. Interagency fire crews are highly trained teams of firefighters who are sent to help fight particularly difficult fires.
A engine crewMeanwhile, he travels to the fire line with a fire truck to pump water or extinguishing foam onto a fire. fuel crew works to remove vegetation that could fuel an advancing fire, possibly through controlled burning.
