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A photo of the Cocos Fire in San Marcos, California.

The Cocos Fire rages near homes in San Marcos, California this week.

PHOTOGRAPH BY SAM HODGSON, REUTERS

Warren Cornwall

for National Geographic

Published May 17, 2014

Investigators around San Diego continue searching for the causes of ten fires that burned thousands of acres of land in the area this week, after determining that one of the blazes was set by sparks from construction equipment.

Whether the other blazes were set intentionally or by accident, experts say it's highly likely that humans are to blame. Two people were arrested north of San Diego on Thursday on suspicion of arson, though it's not clear if they are thought to be connected to this week's big fires. (Related: What's Behind Early Season Winds Fueling Southern California Wildfires?")

Unlike remote parts of the world where natural events like lightning strikes are prime sources of wildfires, in southern California, such fires are almost always started by people. Ninety-five percent have a human cause, according to Cal Fire, the state's firefighting agency.

The situation may worsen in the face of expected population growth. Metropolitan San Diego's population is expected to reach nearly 4.5 million by 2050, over a million more than today. (Pictures: San Diego Wildfires)

"The probability of fires is increasing because people are increasing," said the U.S. Geological Survey's Jon Keeley, who has spent years studying the history of California wildfires.

A photo of a wildfire in Yosemite in 2013.
Trees burn in the Rim Fire near California’s Yosemite National Park last year.
PHOTOGRAPH BY JAE C. HONG, AP

The Wildest Things

Most of the big Southern California wildfires of recent years were found to have human causes.

In 2007 a fallen power line near San Diego set off a fire that scorched nearly 200,000 acres and killed two people.

In 2009, sparks from a weed cutter are thought to have led to an 8,700 acre fire in Santa Barbara County that torched 80 homes.

And earlier this month, an illegal campfire started in Rancho Cucamonga grew to 2,700 acres.

Other area fires have been blamed on chains dragging behind cars and throwing off sparks, smoldering cigarette butts, welding tools, errant gunfire, and arsonists.

"It's anything you could possibly think of," said Alexandra Syphard, a San Diego scientist at the non-profit Conservation Biology Institute who has combed through thousands of California wildfire reports to understand what's causing the fires. "You see the wildest things. One of them was a satanic ritual."

A more common culprit: outdoor equipment, from power saws to lawnmowers. Power tools accounted for more than 20 percent of fires in San Diego County between 2000 and 2010. That was followed by fires caused by campfires (nearly 10 percent), arson (roughly 5 percent), trash burning (around 4 percent), vehicles doing things like sending out sparks or igniting vegetation with overheated tailpipes, downed or malfunctioning power lines, kids playing with fire, and cigarettes.

A photo of a wildfire in Yosemite in 2013.

Blackouts and Leapfrog Housing

Some fire experts see a silver lining to these dreary statistics: If people are mostly to blame for wildfires, they can do something about it.

"Weather doesn't cause fires--weather just causes a fire to burn," said Cal Fire spokesman Daniel Berlant. "It's the people that have the role of actually preventing that fire."

His agency, along with the U.S. Forest Service, the National Park Service and other land managers that deal with wildfires, is leading a public relations campaign urging Californians to reform outdoor habits.

Starting late last summer, the agencies ran "One Less Spark" ads urging people to avoid using power tools during times of high fire danger, extinguish camp fires, and avoid parking cars in tall, dry grass.

In the months ahead, the same coalition plans to use billboards, public service announcements and television commercials to spread messages reminiscent of Smokey the Bear's line: "Only you can prevent forest fires."

Other measures have been more dramatic. For the first time last year, San Diego County's electrical company started shutting down power to electrical lines in places where extreme fire danger prompted fears they could spark blazes.

Last Wednesday, San Diego Gas and Electric put 1,200 customers in the dark during the peak of the Santa Ana winds, said company spokeswoman Allison Zaragoza.

The intentional blackout grew out of the fatal 2007 San Diego fire. The company has since installed more than 140 weather monitoring stations to watch for risky fire conditions and has replaced 3,500 wooden power poles with fire-resistant metal ones.

One of the thorniest issues around mitigating fires is less resolved—deciding where people should build homes. Richard Halsey, author of "Fire, Chaparral, and Survival in Southern California," has watched San Diego area houses built on forested hilltops and in canyons ripe for destruction by a wildfire.

In some cases, such homes are rebuilt after they burn down.

"You look at it and you scratch your head. Why would anybody build their houses there?" said Halsey, director of the California Chaparral Institute, which works to protect the fire-prone chaparral ecosystem that covers Southern California's hills.

The flammability of Southern California in the future could hinge partly on how the region grows.

A study involving both the U.S. Geological Survey's Keeley and the Conservation Biology Institute's Syphard found that sprawling "leapfrog" development—in which subdivisions continually pop up at the edge of the woods, beyond existing developments—would lead to more houses lost to fire in Southern California.

Dense development that fills in the gaps where housing already exists would be the least hazardous approach, according to their models. That's in part because as more land in a certain area gets paved over, there's not enough vegetation left to fuel a wildfire.

That could help explain a slight drop in the number of fires in Southern California recent decades, as development in Southern California shifts from dramatic sprawl to more compact growth, Keeley said.

8 comments
Aaron David
Aaron David

We now live in a post 9/11 America. Since the terrorist attacks on the World Trade Center in 2001, American life has changed. The inevitability of further acts of terrorism has become apparent – the Boston Marathon Bombings being a case-in-point. The above article exemplifies a vulnerable angle for the commission of an act of terrorism within the borders of the United States of America, albeit preventable in pursuance of thorough forethought and proper planning. According to Californian Fire Statistics, 27% of the wildfires throughout the state, during the year of 2012, were caused by undetermined origin (Fire, fire.ca.gov). At face value, wildfires of undeterminable origin might be construed as arbitrary to the layman, as well as to the specialist and expert on the matter. However, a compendium of statistical information of the sort shows that a gubernatorial department of the executive is woefully unaware of how 27% of its state’s wildfires are originated. A Californian inferno is imminent indeed. The Californian terrain is parched. Lake Meade has been practically dried up by a naturally occurring, albeit rare, drought of unprecedented proportions. “Lake Mead stores Colorado River water for delivery to farms, homes, and businesses in southern Nevada, Arizona, southern California, and northern Mexico . . . In an average year, the amount of water flowing out of Lake Mead exceeds the amount of water flowing into Lake Mead” (Lake Mead, nps.gov). A wildfire attack, dependent upon an unfavorable time of year, ambient temperature, wind speed, and wind direction could potentially be cataclysmic; if positioned and equipped with the necessary fire accelerants, opportunists with terroristic intent might ignite the fires in San Bernardino County, Riverside County, and Kern County. The month of October marks the beginning of the Santa Ana season. According to the National Weather Service, The Santa Ana is, “Strong down slope winds that blow through the mountain passes in southern California. These winds, which can easily exceed 40 mph, are warm and dry and can severely exacerbate brush or forest fires, especially under drought conditions” (NOAA Weather Radio All Hazards).

The legislative steps set forth for the local and state government’s emergency response plan are tedious and are littered with legislative red tape. This can potentially waste precious time of potential rescuers, who could otherwise quench the wildfires effectively with efficacy. 

Title 30 CFR 250.1503 does not stipulate how the OCS facilities should design, maintain, and test those safety systems. Section 250 of the Code incorporates by reference within the context of the American Petroleum Institute Recommended Practice 14C. Incorporation by reference is a designation of specific documents or a section of a document within the CFR which is incorporated so as to ensure for the treatment of the designated material therein to be implicitly statutory, albeit its effect and force is that of an explicit lawful requirement; the practice designated therein is no longer merely a recommendation. It’s lawfully binding and thereby enforceable. Indeed, if what’s good for the goose is good for the gander – the oil and gas operations of the OCS is to the goose what the Homeland is to the gander – what’s good for OCS might, likewise, be instrumental towards the security of the American Homeland. If safety devices are required within the Outer Continental Shelf to detect abnormal conditions within a corporate environment, safety devices of similar design and purpose should be designated for the detection of abnormal conditions for the protection of United States citizens within their residential and familial environment(s). If the EPA exists for the protection of the environment, perhaps a new definition for what the EPA defines, as ‘environment’ should be implemented. Fusible elements (TSE’s) are metallic plugs that melt at a designed temperature. Detection of fires by the utilization of pneumatic energy is performed most expeditiously by the placement of seamless 316 stainless steel tubing as a medium for a signal. The tubing shall be three-eighth’s of an inch in outside diameter and 0.049 of an inch in wall thickness. The tubing is branched off and dead-ended with these fusible elements. In conjunction with this common circuit of fusible plugs and tubing is a series of automatically actuated (normally closed for the most part) three way B-valves.

Nitrogen pressure from 60 cubic foot capacity nitrogen bottles will supply the system with its signal pressure. Nitrogen is a nontoxic, odorless, colorless, nonflammable compressed gas stored in cylinders at high pressure. In accordance with Part 5 of the United States Code § 552(a) and Part 1 of the Code of Regulations § 51, “. . . Nitrogen is not listed as a carcinogen or potential carcinogen by NTP, IARC, or OSHA . . . Nitrogen is nonflammable and does not support combustion . . . Nitrogen is not listed as a marine pollutant by DOT (49 CFR 171) . . . Nitrogen will supply three pneumatic pilot valves. The pilot valves will be capable of being actuated by automated remote switch.

Each of the fusible elements is designed to serve as a sort of obstruction at the open end of pneumatically charged tubing. When ambient temperature in excess of 160 degrees Fahrenheit is detected by the element, it melts, thereby allowing the open-ended tubing to expunge its retained internal pressure. This system is capable of providing a remote signal to the proper authorities within a ten-mile radius of each individual control system’s location. Each individual control system will be independent from the rest of the system as a whole inasmuch as each individual system will be codified with its own unique signal frequency, in correlation with its geographical coordinates. These control systems should be strategically placed in areas of critical prioritization for the primary purpose of planning for a most expedient response and extinguishment of Californian wildfires.

The melting of these individually placed fusible elements will immediately expunge the fifty-pound per square inch signal lines and the actuators will cause the series of automated controls to revert to the system’s original state. A 9-volt battery as an (DC) electronic power source will supply sufficient energy to each transmitter. Each transmitter is comprised of a non-guided electromagnetic radiation laser output, a laser-to-voltage converter, and a pressure recorder. These transmitters will transmit an electromagnetic signal for the real-time existence of an open flame to the designated authorities. Furthermore, a pressure indicator, which transmits by way of a non-guided electromagnetic radiation laser output, will allow for televised real-time viewing of each control system’s pressure gage within a ten mile radius from said pressure indicator.

Each individual control system, having been installed and activated 200 yards from one another along the foothills along the San Bernardino, San Emigdio, San Jacinto mountain ranges from the coordinates of 34 degrees, 5’ 55. 0428” North and -116 degrees, 49’ 24. 5928 West, running Northward along the foothills toward Kern County and Los Padres National Forest will serve as protective barriers. The immediate notification of local law enforcement agencies and firefighters is paramount to the design of the aforementioned control system. I have drawn this system myself, and it will assist in the prevention of wildfire spread if my voice is heard by someone who can make it happen. I am an altruist, not a capitalist; Caveat Vendor. 

Jay Dee
Jay Dee

HellLlloooohhh LIGHTNING. Interesting that Cal Fire spokesman Daniel Berlant says here "Weather doesn't cause fires--weather just causes a fire to burn," - WOW. Has Berlant ever heard of LIGHTNING That weather phenomena clearly causes fires. Perhaps one problem is govt oficials who do not know what they are talking about, probably another of California's over paid govt bureacrats, we have tons of those in this state.

Fra Rei
Fra Rei

Build it and they will come.  Fires and people.

Rodger Marjama
Rodger Marjama

Well I suppose before too long everyone will have left California so problem solved.  Then again, you could line up every politician in California to create a human fire break... It could work you know.  At the very least you will have gotten rid of most of the humans in California who are the overwhelming cause of just about every problem (other then fires) in the state.  Sounds like a win win to me.

Jack Wolf
Jack Wolf

And, humans through greenhouse gas emissions, helped to create the tinderbox.

Tamara McMahon
Tamara McMahon

@Jay Dee I live in the foothills of the IE...Lightning has caused many fires in this neck of the woods...we get lots of crazy lightning/thunderstorms in the summer.

Stan Cummings
Stan Cummings

@Jay Dee Lightening in Sol Cal is rare. I lived there for 30 years and saw only a handful of lightening storms.

Dawn Hill
Dawn Hill

@Rodger Marjama How do you figure?  I see no sign of anything but continued invasion of everyone from everywhere in the country until we won't be able to turn around or find a drink of water in the entire state.  And I've been observing this invasion since the forties.  I've been driven from where this story is set to the farthest northern corner, where there is no work and no way to get here without a $500+ airfare or a six-hour drive each way, to escape these hordes.

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