Fire in and Around Fallbrook

The devastating Rice fire of October, 2007 led Tom Chester, of Fallbrook, to take a close look at what happened and why. The results not only pertain to that fire, but also provide information pertinent to fire issues more generally, especially in our area. In the description below we draw upon Tom's observations and conclusions, quoting his web site liberally and paraphrasing frequently. That site contains far more information about fires and the Rice fire in particular than we have included in the following summary, so for those interested in a more thorough treatment please go to that site at the following address: http://tchester.org/fb/fire/071022_sw_rice.html

From Tom Chester's web site:

The fire was caused by downed power lines around 4 a.m., which may have been toppled by strong winds in Rainbow . . . the fire was probably initially spread by strong winds, with gusts up to 70 mph. The winds essentially died down completely soon early Tuesday morning, and were essentially zero thereafter. If the winds in Fallbrook had continued, it is quite possible that much more of Fallbrook would have burned. This was the very-plausible motivation for the evacuation order for all of Fallbrook. Such winds could cause fire to go from I-15 to the coast in less time than people could evacuate.
To understand the Rice fire and other major fire threats here requires an understanding of some basics about wind-driven fire. Many people have the idea that a fire starts in one spot, and then burns in a continuous pattern away from that spot. For example, in a uniform field of wheat, in this model each wheat plant would only burn when the fire perimeter reaches it. Fires in southern California driven by high winds don't burn like that. Embers from fires driven by high winds can start fires up to 1.5 miles away from the "front" of the fire.

Those spot-fires spread in the direction of the wind, and in turn can start new spot fires in whatever direction the wind is blowing there. Every time you hear that a fire "jumped" the freeway, this process was at work, since the concrete freeway doesn't burn. A typical 8 lane freeway width is 400 feet, less than a tenth of a mile. If the wind is blowing consistently in one direction, the fire can essentially leap-frog its way across the landscape, and spot-fires can burn backwards (as well as forwards) and even put out the previous "fire front", replacing that old front with their own.
Aerial attacks on wind-driven fires are virtually useless. The erratic winds will cause most water or fire-retardant drops to miss their target, and disperse them so much that they don't do any good even where they land. Even if the drop hits its target, it hardly matters; the fire has already spread beyond that point. It is also very unsafe to fly in such conditions, and foolish to even try when the chances of success are almost zero.

The two main tools used by firefighters on the ground, constructing containment lines via human labor or bulldozers, and backfires, are also almost useless against wind-driven fire. It is impossible to construct a containment line in front of a fast-moving, wind-driven blaze, since there is no time to create one. Backfires can't be set if the wind never shifts to drive the backfire into the advancing flames. (A containment line is a cleared area that deprives the fire of fuel, and backfires are usually set on the fire side of the containment line to make the containment line much wider. Backfires can sometimes be used without constructing a containment line if the wind conditions are right. A backfire "burns back" to the wildfire and puts it out by removing fuel from its progress.)

The third tool is to try to actually put the fire out using water or fire-retardant, either from the ground or from the air. This is a puny tool compared to the two main tools, and takes much more time and effort than using backfires.

Fighting fires in human landscapes is much harder than fighting fires in natural areas, because firefighters cannot use their two main tools. It would be very unpopular to bulldoze a block-wide line of luxury homes in order to make a firebreak, and then set fire to the homes and landscapes inside the firebreak to burn back to the active fire. All firefighters can do to fight wind-driven fires in human landscapes is to try to protect as many structures as they can safely protect with ground crews, and wait for the wind to stop so the fire can actually then be put out, usually with the considerable aid of aerial attacks.

Note that "defensible space", the clearing of flammable vegetation, woodpiles, etc. around one's house, can not prevent embers from reaching your home during a wind-driven fire, since those embers come from far away. However, if you have defensible space, it has two beneficial effects. First, it will decrease the number of embers reaching your house, since your immediate landscape will not be contributing local embers. Second, it is more likely that firefighters will try to protect your home during such a fire. Of course, defensible space is very important when the wind is not a factor, and can prevent flames and embers from ever reaching your home.

Further note: The past and future of fire in San Diego County

Briefly, long-term records show that fires as large and intense as the Rice fire and the San Diego fire of a few years earlier have occurred from time to time over a very long period. What is different now, we are told, the frequency and the damage: they are occurring more and more often with increasing devastation. One obvious contribution to both of those changes is the enormous increase in human habitation. There are hugely more people to start fires, ordinarily by accident, e.g., many more power lines now than before. And the increase in human habitat means much greater damage from those fires A more subtle consequence of the increased population is the increased difficulty in fighting the fires. For these human reasons alone we have been having and surely will continue to have relatively frequent and devastating fires near here. Then there is climate change, which is unlikely to decrease fire danger. Thus, whatever steps are recommended to minimize the chances and the consequences of such fires are more important than they have ever been.

	Home Our Preserves Activities/Projects News and More Photo Gallery Membership Contact Us Fire in and Around Fallbrook The devastating Rice fire of October, 2007 led Tom Chester, of Fallbrook, to take a close look at what happened and why. The results not only pertain to that fire, but also provide information pertinent to fire issues more generally, especially in our area. In the description below we draw upon Tom's observations and conclusions, quoting his web site liberally and paraphrasing frequently. That site contains far more information about fires and the Rice fire in particular than we have included in the following summary, so for those interested in a more thorough treatment please go to that site at the following address: http://tchester.org/fb/fire/071022_sw_rice.html From Tom Chester's web site: The fire was caused by downed power lines around 4 a.m., which may have been toppled by strong winds in Rainbow . . . the fire was probably initially spread by strong winds, with gusts up to 70 mph. The winds essentially died down completely soon early Tuesday morning, and were essentially zero thereafter. If the winds in Fallbrook had continued, it is quite possible that much more of Fallbrook would have burned. This was the very-plausible motivation for the evacuation order for all of Fallbrook. Such winds could cause fire to go from I-15 to the coast in less time than people could evacuate. To understand the Rice fire and other major fire threats here requires an understanding of some basics about wind-driven fire. Many people have the idea that a fire starts in one spot, and then burns in a continuous pattern away from that spot. For example, in a uniform field of wheat, in this model each wheat plant would only burn when the fire perimeter reaches it. Fires in southern California driven by high winds don't burn like that. Embers from fires driven by high winds can start fires up to 1.5 miles away from the "front" of the fire. Those spot-fires spread in the direction of the wind, and in turn can start new spot fires in whatever direction the wind is blowing there. Every time you hear that a fire "jumped" the freeway, this process was at work, since the concrete freeway doesn't burn. A typical 8 lane freeway width is 400 feet, less than a tenth of a mile. If the wind is blowing consistently in one direction, the fire can essentially leap-frog its way across the landscape, and spot-fires can burn backwards (as well as forwards) and even put out the previous "fire front", replacing that old front with their own. Aerial attacks on wind-driven fires are virtually useless. The erratic winds will cause most water or fire-retardant drops to miss their target, and disperse them so much that they don't do any good even where they land. Even if the drop hits its target, it hardly matters; the fire has already spread beyond that point. It is also very unsafe to fly in such conditions, and foolish to even try when the chances of success are almost zero. The two main tools used by firefighters on the ground, constructing containment lines via human labor or bulldozers, and backfires, are also almost useless against wind-driven fire. It is impossible to construct a containment line in front of a fast-moving, wind-driven blaze, since there is no time to create one. Backfires can't be set if the wind never shifts to drive the backfire into the advancing flames. (A containment line is a cleared area that deprives the fire of fuel, and backfires are usually set on the fire side of the containment line to make the containment line much wider. Backfires can sometimes be used without constructing a containment line if the wind conditions are right. A backfire "burns back" to the wildfire and puts it out by removing fuel from its progress.) The third tool is to try to actually put the fire out using water or fire-retardant, either from the ground or from the air. This is a puny tool compared to the two main tools, and takes much more time and effort than using backfires. Fighting fires in human landscapes is much harder than fighting fires in natural areas, because firefighters cannot use their two main tools. It would be very unpopular to bulldoze a block-wide line of luxury homes in order to make a firebreak, and then set fire to the homes and landscapes inside the firebreak to burn back to the active fire. All firefighters can do to fight wind-driven fires in human landscapes is to try to protect as many structures as they can safely protect with ground crews, and wait for the wind to stop so the fire can actually then be put out, usually with the considerable aid of aerial attacks. Note that "defensible space", the clearing of flammable vegetation, woodpiles, etc. around one's house, can not prevent embers from reaching your home during a wind-driven fire, since those embers come from far away. However, if you have defensible space, it has two beneficial effects. First, it will decrease the number of embers reaching your house, since your immediate landscape will not be contributing local embers. Second, it is more likely that firefighters will try to protect your home during such a fire. Of course, defensible space is very important when the wind is not a factor, and can prevent flames and embers from ever reaching your home. Further note: The past and future of fire in San Diego County Briefly, long-term records show that fires as large and intense as the Rice fire and the San Diego fire of a few years earlier have occurred from time to time over a very long period. What is different now, we are told, the frequency and the damage: they are occurring more and more often with increasing devastation. One obvious contribution to both of those changes is the enormous increase in human habitation. There are hugely more people to start fires, ordinarily by accident, e.g., many more power lines now than before. And the increase in human habitat means much greater damage from those fires A more subtle consequence of the increased population is the increased difficulty in fighting the fires. For these human reasons alone we have been having and surely will continue to have relatively frequent and devastating fires near here. Then there is climate change, which is unlikely to decrease fire danger. Thus, whatever steps are recommended to minimize the chances and the consequences of such fires are more important than they have ever been. ® 2012 Fallbrook Land Conservancy all rights reserved