Fire Behavior Associated with the 1994 South Canyon Fire on Storm King Mountain, Colorado
Wildfires burned millions of acres in 1994 (Russo and Williams 1995). A lightning strike to a ridge ignited one of those fires on July 2, 1994. This fire, named the South Canyon Fire, occurred approximately 7 miles west of Glenwood Springs, CO (fig. 1).
For the next 3 days the South Canyon Fire burned down the slopes in the litter, debris, and grass covering the ground with occasional short duration upslope runs and torching of individual or small groups of shrubs and trees. By late morning on July 6 the fire covered approximately 127 acres. At about 1520 (all times are mountain daylight saving time given in 24 hour format) a dry cold front passed over the area. At about 1600 and for the next 4 hours the fire burned generally north and east through the shrub and tree canopies as a fast moving wind-driven front. It exhibited dramatically greater rates of spread, flame heights, and energy release rates than at any time since its ignition.
The South Canyon Fire eventually burned 2,115 acres and was declared controlled on July 11, 1994. This fire will not be remembered for the acreage burned, but for the lives lost. On the afternoon of July 6, 1994, fire entrapped and killed 14 firefighters, making the South Canyon Fire one of the most tragic wildland fires to occur in the United States this century.
Immediately following the accident an interagency team was formed to conduct an official investigation into the causes of the fatalities. The “Report of the South Canyon Fire Accident Investigation Team” (USDA, USDI, and USDC 1994), hereafter referred to as South Canyon Report, was released in August 1994. A followup report, titled the “Report of the Interagency Management Review Team (South Canyon Fire)” was released in October 1994 (IMRT 1994). This second report presented a corrective action plan for improved firefighter safety based on findings from the first report. A final report titled “Final Report of the Interagency Management Review Team” was issued in June 1995 (IMRT 1995). This report summarized accomplishments since release of the corrective action plan and made further recommendations for improved firefighter safety. The Occupational Safety and Health Administration also investigated the incident and presented a report (OSHA 1995).
Time constraints limited the original accident investigative team from studying the fire behavior in detail. This report presents a more detailed picture, than has been presented previously, of the factors that led to the dramatic change in fire behavior on July 6, 1994. Information and data were gathered from many sources including investigation reports, firefighter interviews, site visits, and related scientific literature. The information presented in this document refines previous work by the accident investigators.
Unfortunately, during most wildfires, there is little documented quantitative information about the fire spread during times when the fire is most active. Such was the case for the South Canyon Fire. Given the lack of quantitative fire behavior data, we reconstructed the fire behavior from witness statements and information about the vegetation, topography, and weather present at the time of the fire. To accomplish this we first developed a detailed chronology of firefighter locations and movement during the time of interest. The chronological history for the afternoon of July 6, 1994, occupies a significant portion of this report. We believe that this information is necessary to understanding the fire behavior. Using the witness statements about the location and behavior of the fire and the chronology, we were able to develop a sequence of fire perimeters.
The behavior exhibited by the South Canyon Fire on July 6, 1994, was extreme in terms of intensity; but it can also be termed normal for the fuel, weather, and topographical conditions present at the time. Similar alignments of influencing factors and the resulting fire behavior are not uncommon.
We present a summary of the South Canyon Fire and some key factors that influenced the fire behavior. We describe the topography, the vegetation or fuel, and weather present during the fire. This is followed with a chronological narrative of firefighter movements and fire perimeter locations prior to and during the blowup and entrapments. Finally, key fire behavior points are discussed and summarized. Our reconstruction of the fire behavior is based on best estimates of fire spread rates, firefighter travel times, and witness statements. When specific statements or information from witnesses are used, we cite the source.
We frequently use the terms “intensity” and “blowup.” In the general sense, “intensity” implies the size of the flames, the fire’s spread rate, and the rate of energy release from the fire. “Blowup” indicates a rapid change from a low intensity surface fire, to a high intensity fire burning through the whole vegetation complex, surface to canopy, and demonstrating dramatically larger flame heights, higher energy release rates, and faster rates of spread. We define other terms used in this report in appendix A.
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