Updated: 10 p.m. July 21

First discovered: 33 hours ago, 12:51 p.m. July 20

Initial location: Alta Airosa Drive, east of Oroville, Butte County, Calif.

Fire unit: Cal Fire Butte Unit

Fire type: Wildfire

Fire name: Alta Fire

Alta Fire initially started 12:51 p.m. July 20 in Butte County, California.

Since its discovery 33 hours ago, it has burned 17 acres. By Monday evening, a fire crew of 19 has achieved full containment of the blaze. However, investigations into the cause are ongoing.

According to Cal Fire, “Numerous firefighting air tankers from throughout the State are flying fire suppression missions as conditions allow.”

Fire containment

What does 100% containment mean?

Note that full containment doesn’t mean the fire is completely out. In this case, it means that the wildfire has been fully enclosed by a control line and it is now stopped from spreading. A fully contained wildfire may continue to burn within the containment perimeter but is not likely to spread.

However, there’s a significant difference between containing and controlling a wildfire. After the fire is fully contained, the next step is to control it. Controlling a fire means ensuring that the fire can’t spread or cross the containment line.

Containment is part of a larger plan for managing a wildfire. It is normally expressed as a percentage and it refers to how much of the fire perimeter has been surrounded/enclosed by a control line that firefighters create. The containment percentage indicates a certain level of control, but it doesn’t always correlate to safety level. Also, it’s important to note that containment doesn’t mean a fire is out.

How is containment measured?

The incident’s central command constantly receives progress reports from firefighters on the ground. As the fireline is constructed, inspected or reinforced, mappers record those details to adjust the containment percentage. The percentage tells the public how much of the fire perimeter is believed to not go beyond the control lines.

Source: Cal Fire