Fires in Nature - Natural Hazards - page 144

In southern California, nearly a third of all fires are
started by children, most of whom are boys playing
with matches. Throughout the twentieth century in
the United States, economic downturns have brought
increased incendiarism, because firefighting affords
temporary job opportunities for the unemployed. The
major difference between arson and lightning as a
cause of fire is the fact that lightning-induced fires tend
to become conflagrations because they occur in
isolated areas, while arson-induced fires tend to occur
in accessible areas that are relatively easy to monitor
and control. In the United States 2000 fire season,
lightning caused 7659 fires burning out 4930 km 2 of
vegetation. In contrast, humans caused 96 390 fires
that burnt across 10 050 km 2 . Of this number,
30 per cent were due to arson and consumed
34 per cent of the area burnt.
In Australia, the causes of fire are more numerous
because of the variety in vegetation, climate, and land-
use. Additionally, prescribed burning as a fire preven-
tion procedure is practiced more in this country than
any other part of the world. This is despite the fact that
prescribed burning was used in the south-east United
States for clearing undergrowth and minimizing the
outbreak of major fires. Between 1966 and 1971 in
Western Australia, 36 per cent of all fires resulted
from burning-off; only 8 per cent were due to light-
ning. Vehicles, farm machinery, and trains ignited
15 per cent of all fires, with carelessness accounting for
21 per cent. In the Northern Territory, most fires are
caused by either lightning or burning-off. Here,
Aborigines traditionally light fires to clear the land-
scape so they can catch game. In eastern Australia,
where the population is greater, arson has become a
major cause of fires in recent years. Single individuals
have been found to light more than one fire on a high
fire-risk day. Because the spring burning-off season can
encroach upon early warm weather, notably during
ENSO years, the incidence of fires caused by burning-
off has also increased in recent years.

of life can still occur in northern hemisphere temper-
ate forests, most destruction is evaluated in terms of
the loss of marketable timber. This statement needs
qualification because timber has no value unless it can
be accessed, and there is no imperative to access it
unless it is close to centers of consumption. In North
America, it is mainly the forests lying within 1000 km
of dense urban development that are used to supply
building timber, unless there is a need for timber with
specific qualities - such as the Californian Redwood.
Beyond this distance, forests are mainly used to supply
pulp and paper in the form of newsprint. There are
large areas in the Canadian and Alaskan boreal forest
where no harvesting of trees takes place because it is
uneconomic. These areas generally are uninhabited
and no attempt is made to suppress forest fires.
Fires are allowed to burn uncontrolled, and may take
weeks or the complete summer season to burn out. In
northern Canada, it is not uncommon for such fires to
cover thousands of square kilometers.
In the Middle Ages, large areas of Europe were
subjected to forest fires. Damage and loss of life has
gone virtually undocumented, although it is estimated
that today's conflagrations cover only 20 per cent of the
area they did centuries ago. Today, large tracts of
deciduous, mixed and chaparral forests remain in
which fires pose a serious threat. In Europe as recently
as 1978, over 43 000 fires consumed 440 000 hectares
of forest and as much again of grasslands and crops.
These figures are not remarkable. No European
country has had more than 2 per cent of its total forest
cover burnt in a single year. Individual fires on a much
larger scale have occurred throughout the northern
hemisphere. In October 1825, over 1 200 000 hectares
of North American forest burned in the Miramichi
region of New Brunswick, together with 320 000
hectares in Piscataquis County, Maine. The Wisconsin
and Michigan forest fires of 1871 consumed 1 700 000
hectares and killed 2200 people. Areas of similar
magnitude were burnt in Wisconsin in 1894 and in
Idaho and north-western Montana in 1910. The Por-
cupine Fire of 1911 raced unchecked from Timmins,
Canada, north through virgin forest for over 200 km,
killing scores of settlers on isolated farms. During
the 1980 Canadian fire season, virtually the whole
mixed forest belt from the Rocky Mountains to Lake
Superior was threatened. Over 48 000 km 2 of forest
were destroyed, with a potential loss equivalent to the
timber required to supply 340 newsprint mills for one

BUSHFIRE DISASTERS: WORLD
PERSPECTIVE

(Cornell, 1976; van Nao, 1982; Seitz, 1986;
Couper-Johnston, 2000)

Bushfires as a hazard are usually evaluated in terms of
loss of life, property damage (burning of buildings or
entire settlements), and the loss of timber. While loss