As wildfires become more common across Oregon, residents need to be informed about wildfire characteristics. But it can be hard to sift through jargon and firefighting terminology.
To better understand concepts related to wildfires, their causes, their impacts and fighting them, here’s a look at some of the terminology that fire officials and crews use.
ODF crews work on a blaze outside Sweet Home, Oregon.
Oregon Department of Forestry
Fire Season
Period(s) of the year when wildland fires are likely to occur, spread, and stretch local firefighting resources thin. In Oregon, fire season typically begins in June and peaks in mid-August.
Firefighting
Burn Out
Setting fire to fuel inside a control line to consume it and widen the line. This can reduce the risk of the wildfire crossing the control line by reaching unburned fuel.
Containing vs. controlling a fire
Containment means a fuel break around the fire’s perimeter has been completed. This may include natural barriers or manually and/or mechanically constructed line. When a fire is contained, its spread has been limited. This does not mean the fire is completely extinguished.
Control means the complete extinguishment of a fire, including spot fires. The fireline has been strengthened so that flare-ups from within the perimeter of the fire will not break through this line.
Control Line
All built or natural fire barriers and treated fire edges used to control a fire.
Division
Used to divide an incident into geographical areas of operation. Divisions are established when the number of resources exceeds the span-of-control of the operations chief.
Entrapment
A situation where personnel are unexpectedly caught in a fire-related, life-threatening position, leaving them unable to access planned escape routes or safety zones.
Fire Break
A natural or constructed barrier used to stop or check fires that may occur, or to provide a control line from which to work.
Fire Shelter
An aluminum-based tent that offers protection by reflecting heat and providing breathable air if a firefighter is trapped within a wildfire. Fire shelters are generally used in life-threatening situations, as a last resort.
Hand Line
A fireline built with hand tools.
Mop-up
To make a fire safe or reduce leftover smoke after the fire has been controlled. This is done by extinguishing or removing burning material along or near the control line, felling snags, or moving logs so they won’t roll downhill.
Retardant
A substance or chemical agent that reduces the flammability of combustibles.
Safety Zone
An area cleared of flammable materials and used for escape if a fire line is unsuccessful or if a spot fire makes the line unsafe. They are greatly enlarged areas that can be used with relative safety by firefighters and their equipment in the event of a blowup in the vicinity.
Test Fire
A small fire ignited within the planned burn unit to determine the characteristics of a prescribed fire, like fire behavior, detection performance and control measures.
Types of fires and their causes
Aerial Fuels
All live and dead vegetation in the forest canopy or above the ground, like tree branches, twigs and cones, moss, and high brush.
Backfire
A fire set along the inner edge of a fireline to consume the fuel in the path of a wildfire and/or change the direction of force of the fire.
Brush Fire
A fire burning in vegetation that is mostly shrubs, brush and low, woody plants.
Campfire
One common cause of wildfires, meaning a fire that was started for cooking or warming that spreads enough to require action by a fire control agency.
Crown Fire
A fire that spreads through the tops of trees or any other aerial fuels.
Dead Fuels
Fuels with no living tissue. These can be dead plants, fallen logs and brush piles.
Debris Burning
The No. 1 human cause of wildfires in Oregon; a fire originally set for the purpose of clearing land, rubbish, garbage, or for meadow burning.
Escaped Fire
A fire that has exceeded or may exceed the initial expectation of its spread.
Fire Storm
A violent storm caused by a large continuous area of intense fire. It is often characterized by surface destruction, near and beyond the perimeter of the fire, and sometimes by tornado-like whirls.
Flash/fine Fuels
Fuels like grass, leaves, draped pine needles, fern and tree moss that ignite readily and are consumed rapidly when dry.
Heavy Fuels
Larger fuels like snags, logs and large limb wood, that ignite and are consumed more slowly than flash fuels.
Holdover Fire
A fire started through organic material under a burn pile that continues to smolder during the winter months and sparks when weather conditions become dry and hot.
Incident
A human-caused or natural occurrence, such as wildland fire, that requires emergency service action to prevent or reduce the loss of life or damage to property or natural resources. Can also be a fire burning with enough size and intensity that its behavior is determined by interaction between its own convection column and weather conditions above the surface.
Ladder Fuels
Fuels that provide a vertical path for a fire, allowing fire to easily carry from surface fuels into the crowns of trees or shrubs. Common ladder fuels include tall grasses, shrubs, and tree branches.
Live Fuels
Living plants, like trees, grasses, and shrubs.
Prescribed Fire
Any fire ignited by fire management under predetermined conditions to remove old vegetation and make room for new growth. A written, approved prescribed fire plan must exist, and NEPA requirements must be met, prior to ignition.
Smoldering Fire
A fire burning without flame and barely spreading.
Spot Fire
A fire ignited outside the perimeter of the main fire by flying sparks or embers.
Structure Fire
Fire originating in and burning any part or all of a building, shelter, or other structure.
Surface Fuels
Loose surface litter on the soil surface, normally consisting of fallen leaves or needles, twigs, bark, cones, and small branches.
Uncontrolled Fire
Any fire that threatens to destroy life, property, and natural resources.
Underburn
A fire that consumes surface fuels but not trees or shrubs.
Fire condition descriptors
Burning Period
The part of each 24-hour period when fires spread most rapidly, typically from 10 a.m. to sundown.
Candling
A single tree or a very small clump of trees burning from the bottom up.
Crowning
The movement of fire through the crowns of trees or shrubs independent from the surface fire.
Extreme Fire
“Extreme” refers to a level of fire behavior that makes direct control action difficult or impossible. This could mean a high rate of spread, high crowning and/or spotting and fire whirls. Predictability is difficult because these fires influence their environment and behave erratically.
Large Fire
According to the National Wildland Coordinating Group, a large wildfire in Oregon is a wildfire that has burned 100 acres or more in timber, 300 acres or more in grasslands or rangelands, or has an Incident Management Team assigned to it.
Rate of Spread
A rate of increase of the total perimeter of the fire, rate of forward spread of the fire front, or rate of increase in area, depending on the intended use of the information. Usually measured in acres per hour for a specific period in the fire’s history.
Running
A fire that is rapidly spreading on the surface and has a well-defined head (the part of fire spreading at the fastest rate).
Do you know the different parts of a fire? This is an important concept captured in this diagram (by OSU), to help clearly identify the different parts of a fire. Heading fires typically have faster rates of spread while backing fires will have slower rates of spread. #RxFire pic.twitter.com/eD4Im90kQM
— Oregon State University Extension Fire Program (@OSUFireProgram) December 22, 2021
Parts of a fire
Blow-up
A sudden increase in fire intensity or rate of spread strong enough to prevent direct control or to upset control plans. Blow-ups are often accompanied by violent convection and may have other characteristics of a fire storm.
Buffer Zone
An area of reduced vegetation that separates wildlands from vulnerable residential or business developments. These areas can include crop fields, recreation areas, parks, or golf courses.
Fingers of a Fire
The long narrow extensions of a fire projecting from the main body.
Flare-up
Any sudden acceleration of fire spread or intensification of a fire. Flare-ups last a relatively short time and do not radically change control plans.
Head of a Fire
The side of the fire that spreads at the fastest rate.
Heel of a fire
The end opposite the head, closer to the point of origin. It usually burns into any prevailing wind and burns with low intensity.
Hotspot
A particularly active part of a fire.
Perimeter
The perimeter is the entire outside edge or boundary of a fire or burned area.
Tools
Fire Cache
A supply of fire tools and equipment assembled in planned quantities at a strategic point for exclusive use in fire suppression.
Fire Rake
A rake that can reach fire in undergrowth and loosen surface debris.
Pulaski
A combination chopping and trenching tool, that combines an axe-blade with a narrow trenching blade fitted to a straight handle. Used for digging or chopping.
Spark Arrester
A device installed in a chimney, flue, or exhaust pipe to stop the emission of sparks and burning fragments.
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Most terms and definitions are from InciWeb