The mountains form a granite berm that bounds the region: for fire purposes, Southern California is what lies west and south of the chain of ranges hoisted up along the San Andreas. They seem as permanent as Earth itself, and their dynamism only that of the rhythms of deep time, irrelevant to the quick tempo of wind and flame. But in fact, they are many and varied, they affect every feature of fire behavior, and they can of their own accord dominate even a large burn.
The mountains each have their own character. The Peninsulars resemble squat fault-blocks, tilting gently to the sea, gouged into mesas and channels. The San Bernardino and San Jacinto mountains pivot around giant peaks. The western Transverse resembles a wooden branch flexed enough to break it lengthwise, so that it splinters above Ojai and fans out from the west-trending Santa Ynez upward into the San Rafael and Sierra Madres. The San Gabriel Mountains, mid-way in the Transverse, are most distinctive by being the simplest. They stand as a colossal massif, rudely shaped like a football, separated by major passes east and west.
Those textured terrains influence how fire behaves, braking or boosting other factors. They make the Santa Anas possible by damming and compressing desert air, then directing the overflow through mountain spillways and weirs. They deform climate by letting air rise and fall over the great berm and fracturing a regional norm into thousands of microclimates and a mosaic of local weathers. What is true on a north-facing slope will differ from a south-facing; alluvial fans, from summits; wrinkled ravines, from exposed ridges. Vegetation will thin and thicken accordingly, display different levels of fuel moisture content, and crumble arrays of combustibles into biotic niches. Fuelbreaks will work when they function like levees, bolstering the terrain, and fail if they cross the grain of terrain-sculpted fire flow. And landscape texture will influence where and how fires begin by influencing the placement of roads and trails.
By guiding the movement of people those routes affect both fire starting and fire suppressing. People will kindle ignitions along routes of travel – literal lines of fire. Those same roads, trails, and fuelbreaks will transport firefighters and become firelines. Terrain will define natural units of fire spread and containment, and it will dictate – or should – how fires might be attacked. Over and over, on a 20- or 30-year rhythm, like a cycle of earthly sunspots, the big fires reappear in the same places, burning in more or less the same way. The vegetation regrew, the winds returned, the terrain-crafted basins that contained fires’ behavior filled with flame. Over-ignition and exotic grasses might quicken the cycle so they burned more often, as in the San Gabriel canyon, but the larger terrain inscribed the pixels that determined how and where fire went. Defy that geographic logic and you risk losing lives as well as firelines.
§ That last cautionary precept is the story repeated sickeningly over and over in fatality fires as crews find themselves on steep slopes with fire below them. That lethal flame might be a reckless burnout. Or a hooking fire, creeping down from one ravine and entering another below a spur. Or a spot fire, from who-knows-where, that plants itself below a chimney and flashes up through anyone unwise or unlucky enough to be in its way.
It’s doubly diabolical because the inclines that can shoot fire upward also slow firefighters to a crawl. Caught on a slope is what happened to a pickup crew at Griffith Park in 1933 and killed 25, to Marines when the Hauser Creek fire killed 11 on November 2, 1943, and to a Forest Service inmate crew from the Viejas Honor Camp that killed 11 at Inaja on November 25, 1956. That is what happened to the El Cariso Hotshots on November 1, 1966 when they tried to cut line across and down a chimney on the San Gabriels and a spark sent a blowtorch of flame upward and killed 11. And it is what happened in August 23, 1968 when the Canyon fire on Glendora ridge of the San Gabriels blew over eight firefighters from the L.A. County Fire Department.
That burn vividly demonstrated the varied but cumulative power of terrain. Fire season was well advanced, but not notoriously droughty or prolonged. Winds were light – this was not classic Santa Ana weather. Fuels were mixed but generally also light – the fire burned through grass, oak, shrubs, and soft chaparral. Instead, what controlled virtually every aspect of fire spread was terrain. Repeatedly, fires burned across Glendora Ridge ravine by ravine. Slowly it crept down, entered a new arroyo, and then rushed up. On the day of the disaster fire “slopped over” the head of an adjacent ravine around 11am, and painstakingly crawled down through litter below the mixed scrub. Approximately 11:24am it flashed in a patch of sumac and scrub oak. What made this flareup similar to the 1959 Decker fire but different from others was that it captured a whirlwind – almost certainly the result of turbulence over the rough countryside – and became a firewhirl. The firewhirl hurled a firebrand below the ravine in which the crew from Camp 4-4 was working. Probably “not more than a minute” later, and perhaps no more than 30 seconds, that flash ignition had blown up, blasted through the ravine, and savaged the crew. The fire’s behavior, a review board concluded, was “almost entirely controlled by the topography.”[i]
§ That tragedy was keenly on the minds of the crews from LACFD and the USFS when, 41 years later almost to the day, a fire broke out on the Angeles National Forest along the Angeles Crest Highway. Again, winds were light and fuels were volatile but not outside norms for age and season. Suppression resources were abundant. The critical circumstance for what became the Station fire was terrain.
It magnified ignition and compromised suppression. An arsonist had craftily kindled the start where it would do the most damage. The highway, the anchor point for a fireline, was mid-slope, which ranged between 33-67%. Visibility was poor, access feeble, foot travel tricky, and the opportunities high for spotting both above and below the point of origin. A board of inquiry concluded that the landscape was “extremely difficult, if not impossible, to traverse without a high degree of exposure to hazard.” It effectively neutralized an impressive initial attack force: nine handcrews, thirteen engines, three water tenders, four medium helicopters, one heavy helicopter, three heavy airtankers, and an Airco helicopter, two patrols, and four chief officers from the two agencies. The setting simply didn’t allow for such massive deployment, like a field army forced to fight in a city of narrow streets and alleys. Spot fires below the highway remained inextinguishable by aerial attack alone and yet inaccessible to ground forces. The serial spotting, which continued through the evening as flare-ups made runs upslope and flung firebrands, overwhelmed any chance at control. By the next afternoon a Type I incident management team had been ordered.[ii]
The Station fire burned and burned. It burned day after day, week after week, basin after basin. It burned the grasses and soft chaparral at the bottom of ravines and the forests at the mountain peaks. It burned from its own momentum and from burnout operations along ridgelines. It billowed smoke behind Los Angeles like Mount Vesuvius outside Naples. It burned until 10 October 2009. It ended, that is, before the season for Santa Anas. At a final tally of 160,577 acres the Station fire was the largest in the annals of the Angeles National Forest and the tenth largest in modern California history.
Something this vast and this visible can be parsed many ways. It was an arson fire, of course. It was a fuel fire – there was more than enough to burn in all directions. But the ignition took because it couldn’t be suppressed safely; the fuels were in no way uniform, unusually dry, or exceptionally heavy, and burned because slopes and narrow canyons channeled flames and scattered spots. The winds that propelled it were largely local, the outcome of diurnal warming and cooling in textured hillsides that guided flow up and down. The fire burned, in brief, because of where it occurred. It was a terrain fire. And it challenges assumptions about the taxonomy of fire in Southern California as much as it did initial attack.
§ But there is more. A fire’s size does not measure its significance. A 100-acre fire in the frontcountry can trump a 100,000 acre fire beyond the ridgeline. What matters is how visible the burn is to the culture; whether houses burn, whether people die, whether someone is present to transcribe the smoke into pictures and words. Little can be hidden on the Angeles. It forms a backdrop to the largest metropolis in the U.S. and to a major media mecca. It is a backlot to Hollywood. As powerful, a state statute known as rule 409.5, unique to California, allows all credential agents of the media full access to any emergency scene and makes the fourth estate a fourth side to the regional fire triangle. No one should wonder that the Angeles has the largest fire budget in the national forest system and co-manages with the largest-budget county fire department in the country.
In some regions, geology obscures. It removes fire from direct contact with society, it renders the flames invisible. In Southern California the reverse holds. The San Gabriels thrust fire against the city with almost no mediating landscape, or media baffles, between them. A fire like the Station or the Gap or the Woodwardia can’t remain out of public sight. It is impossible for an agency to perform without an audience of millions of critics and catcalls. In the case of the Angeles – here synecdoche for all of Southern California – terrain affects not just fire behavior but the behavior of people toward fire.
July 2011 / [pdf]
Acknowledgements: I benefited enormously from a morning’s discussion with Mike Rogers, Don Garwood, and Jack Lane, organized by Diane Travis, who also supplied some background data. The group had probably a century of on-the-ground fire experience in the San Gabriels. I’m indebted to all of them for their insights. It should go without saying, however, that my treatment brushes against only a tiny edge of the Angeles fire story. Nor should anyone assume that my choice of topic and treatment agrees with theirs.
[i] Clive M. Countryman, Morris H. McCutchan, and Bill C. Ryan, “Fire Weather and Fire Behavior at the 1968 Canyon Fire,” US Forest Service, Research Paper PSW-55 (1969), pp. 17-18.
[ii] U.S. Forest Service, Fire and Aviation Management, “Station Fire Initial Attack Review. Report of the Review Panel” (November 13, 2009), pp. 7-10.