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The LAFD reported that the Getty fire near Los Angeles is "5% contained". What is meant by "containment" and what does 5% containment mean in this context? I've tried googling "wildfire containment" but all I'm getting is news articles about a different currently ongoing wildfire.

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  • $\begingroup$ Note: I asked this here because I noticed there were other questions on wildfires, including a tag for the topic, so I assumed that it fits here, even though I'm not sure containment itself fits within the scope of ES. $\endgroup$ – Nzall Oct 29 '19 at 12:31
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    $\begingroup$ google.com/… - the addition "definition" is usually a good idea. $\endgroup$ – Erik Oct 29 '19 at 12:51
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One hundred percent contained means that there are suitable fire guards around 100 percent of the circumference of the fire. The fire guards can be either created such as a hand or machine dug firebreak, a retardant break (often placed by air tanker), or a natural feature such as a river or bare rock cliff. Containing a fire is just a step in controlling the fire, after containment, there are other phases that may or may not be completed such as back burning off the break lines, extinguishment, and finally monitoring. Even once a fire is 100% contained it is not that uncommon for the fire to "jump the guard" if the weather conditions change. The percentage of containment also gives an indication as to how much access the fire crews have to the fire, a well-contained fire implies that the fire crew has access to be able to fight the fire, this is the major secondary goal for the dug firebreaks.

5 percent contained implies that some form of command has been established and the fire crew(s) are just starting to contain the fire. I wouldn't read much more into the statement.

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  • $\begingroup$ On the other hand, low values may also cause undue distress sometimes, at least I believe I've seen so in a few past events I've paid higher attention to (mainly in flatter topography). The key doesn't seem to be what % is contained overall, but how much containment there is downwind. There, all else being equal, will be where they often focus resources, (along the forward flanks, if difficult to shut down the head, to at least limit lateral growth). So a few % can sound horrible to people near the fire, but with reasonable winds can mean they are making good progress in confining the fire. $\endgroup$ – JeopardyTempest Nov 5 '19 at 9:47
  • $\begingroup$ (In other words if winds are expected to be from the south for the next 3 days, there is little need to establish much perimeter on the southern half of the fire. They may only need to establish like 10% containment on the very N/NE/NW edges of the fire to basically slow expansion to a crawl, and then have ample time to get ahead of future shifts and further surround the slower areas. Winds prediction is so vital in wildfire fighting, and part of what I believe makes fire fighting in the west so difficult, where terrain-induced circulations often bring major quick shifts in localized areas) $\endgroup$ – JeopardyTempest Nov 5 '19 at 9:48
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    $\begingroup$ @JeopardyTempest, you are more or less correct in your statements. Control generally starts at the access points and follows the flanks of the fire, though this is very site specific. We don't want to put men or equipment at risk by jumping into the front of the fire. The plan of attack may change with homes or infrastructure at risk, but then the fire chief has access to more equipment such as larger cats, helicopters, and air tankers. Media tends to focus on simple metrics, that without some background are really quite meaningless. $\endgroup$ – user824 Nov 5 '19 at 23:00
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One hundred percent contained would mean that the fire had been completely stopped from spreading further, but not necessarily been put out. By five percent contained, which is only an approximate figure, the commentator meant that the fire was still spreading but, thanks to the firefighters efforts, to a slightly lesser extent than it had been earlier.

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