Updated: 6:28 p.m. July 21

First discovered: 11 hours ago, 6:32 a.m. July 21

Initial location: Mead Valley, Riverside County, Calif.

Fire unit: Cal Fire Riverside Unit

Fire type: Wildfire

Fire name: Rider Fire

Rider Fire initially started today at 6:32 a.m. in Mead Valley in Riverside County, California.

As of Tuesday evening, it had destroyed 140 acres. By Tuesday evening, the fire crew managed to contain 10% of the fire. There is currently no information on the cause of the fire.

Fire containment

What does it mean for a fire to be 10% contained?

The percentage indicates how much of the fire perimeter has been surrounded by a control line. In this case, it means that 10% of the wildfire is contained from spreading, while 90% is still uncontrolled.

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