Fires in Nature - Natural Hazards - page 147

The great fires of 1871 were the first, and by far
the worst, to sweep the Lake states. Ironically they
occurred in October on the same day as the Great
Chicago fire. In the weeks preceding the fires, much of
the countryside was continually ablaze. Almost all able-
bodied men were employed in fire suppression, and
many inhabitants had inaugurated procedures to
protect buildings. On 8-9 October the fires broke into
firestorms only ever witnessed on a few other occa-
sions. Flames leapt 60 m into the air and were driven
ahead at a steady rate of 10-16 km hr -1 by spot fires,
intense radiation, and updrafts being sucked into the
maelstrom. The approach of the flames was heralded
by dense smoke, a rain of firebrands and ash, and
by combusting fireballs of exploding gases. Winds of
100-130 km hr -1 picked up trees, wagons and flaming
corpses. The fire marched with an overpowering roar
like continual thunder or artillery barrages. Hundreds
were asphyxiated hiding in cellars, burned to death
as they sheltered in former lakebeds converted to
flammable marshes by the drought, or trampled by
livestock competing for the same refuges. The Lake
fires were certainly the worst in documented history
and show how vulnerable any forest can be under the
right fuel and climatic conditions.

stoked the fires despite the 9000 firefighters brought in
to contain them. By mid-August, at least eight separate
fires were burning at rates as high as 20 km day -1 with
temperatures exceeding 32°C. By the time the fires
were finally extinguished, 5666 km 2 of forest had been
burnt. Some of the best natural scenery in the United
States had been scarred for decades and a debate was
ignited pitting those who favored a laissez faire attitude
to fires against those who favored complete suppres-
sion. Supporting the former view was the fact that in
the previous twelve years, 235 fires had been ignited by
lightning, allowed to blaze, and had died out after
burning an average of 0.4 km 2 of forest. The largest fire
destroyed only 30 km 2 and had threatened no lives.
Slowly people came to realize that the 1988 fires
were an indication that a 'natural order' was being re-
established - one that had been upset for a century.
Suppression of fires for over a century had allowed an
ecosystem to develop that would otherwise have been
returned, by fires every ten to 20 years, to a more
natural state. The forests in Yellowstone generally
become more flammable as they age. This is because
old-growth forests accumulate greater amounts of
dead biomass at ground level and are susceptible to
crown fires because the trees are taller with unpruned
lower limbs. The Yellowstone fires had reached this
limit in the 1930s, but benign climate and the intro-
duction of fire suppression had extended the fire-prone
state. The suppression consisted of 'Smokey the Bear'
technology and heroics. Aircraft and helicopters
scoured the landscape for the first sign of fire, water
bombers attacked even the most remote flame, and
smoke jumpers were parachuted into sites within
hours of ignition. All fires were to be suppressed by
10 o'clock in the morning. The fires of 1988 were part
of a natural 200-300-year cycle of fire that was delayed
by 30-40 years of efficient fire suppression.
Opposing fire suppression was the view that
nature should be aided by prescribed burning. Had
the Yellowstone forests been culled artificially by
sanctioned arson, under weather conditions disadvan-
tageous to fire, then the smoke that hid the scenery,
affected health and deterred the tourists would not
have been so extreme. The Yellowstone fires fuelled
the view that forested landscapes, burnt or unburnt,
have different values to diverse interest groups.
The Oakland, California, fire of October 1991 was
not the first fire to sweep the area. From 1920 to 1995
over 3500 structures were lost to fire in the East Bay

Recent disasters

Despite these efforts to identify the fire regime and
come to terms with urban encroachment on forest,
fires in North America continue to be a major hazard.
Three events in recent years illustrate the range of
problems: the Yellowstone fire of 1988 because it
pitted advocates for natural burns against those for
total fire suppression; the Oakland fire of 20 October
1991 because it characterizes the urban threat; and the
2000 fire season because it shows how widespread
the problem can be during regional drought.
The Yellowstone fire was impressive for its intensity.
More area was burnt in the region on 20 August 1988
than during any decade since 1872. The fires were
ignited in June by lightning following six years of
above-normal rainfall. For the first month, the fires
were allowed to burn unchecked; but in mid-July, after
35 km 2 had been burnt, a decision was made to contain
them. A week later this area had doubled and a month
later 1600 km 2 had been incinerated despite massive
efforts at suppression. The dramatic increase in
burning was due to drought conditions that were the
worst since the 1930s. Winds as high as 160 km hr -1