Even while a wildfire is being brought under containment, the process of making sure it doesn’t get a chance to reignite begins. It’s called “mop up” and firefighters work to ensure that smoldering hot areas along the fire line are safely cooled down.
To make certain no stone or in this case branch is not overturned, firefighters often use their bare hands to feel for warm areas on the ground and then use a combination of water and hand tools to stir up and cool off hot spots.
Meanwhile, even if it looks like the fire is soon to be completely contained, crews continue to dig fire lines (wide superficial trenches) to enclose the entire perimeter of a blaze. Sometimes this can take days and it’s not uncommon for mop up work to continue a week or so after the news media has left and residents are being allowed back into neighborhoods that had been evacuated during the fire.
"After a wildfire is mostly contained, firefighters work to get fire lines around much of the affected area and ensure that remaining hot spots are cold and mopped up. In fact, a fire is never fully contained until firefighters are confident that remaining hot spots have little opportunity to escape containment lines.” said Mike Ferris, a public information officer with the National Incident Management Organization of the U.S. Forest Service.
Ferris added that the process is weather dependent, and hot dry conditions could cause some areas of a fire to again flare up.
"There's always the potential for wind to hit some isolated hot spots, even when you think the incident is over,” said Ferris. “Usually when this happens it can cause some flare ups and some individual tree torching, but most of the time we can quickly contain it.”
For these reasons firefighting experts caution returning residents to be aware of potential dangerous flare-ups and hazardous trees because a fire is not over until it’s completely out.