Geoscience Reference
In-Depth Information
reducing the efficacy of communication. On the day
of the disaster, many communities had to rely upon
their own resources to cope with the blazes because
professional assistance was unavailable or non-
The Ash Wednesday fires of 16 February 1983
caused substantial death and injury. The 1982-1983 El
Niño-Southern Oscillation event produced the worst
drought in Australia to that point in time. Bushland
and grasslands were desiccated. While the weather
conditions of 16 February had occurred often through-
out the summer, temperature on the day rose above
40° C accompanied by winds gusting over 60 km hr -l .
Weather forecasts accurately predicted one of the
hottest and driest days of the summer. Hot, dry air
flowed strongly from the interior of the continent,
reinforced by the subtropical jet stream in the upper
atmosphere. A strong cool change was forecast to
cross the south of the continent in the afternoon and
early evening, bringing some relief to the desiccating
conditions. For weeks, total fire bans had been
enforced and broadcast hourly over much of south-
eastern Australia. Bushfire organizations and volunteer
firefighters in South Australia, Victoria, and New South
Wales were put on alert. Every human resource was
available and ready.
There was little anyone could do to stop the fires. By
noon, much of Adelaide was ringed by fires and at
3:30 pm the cold change swept through. The change
dropped temperatures 10°C, but the winds increased
and drove the fires to the north-east. In Victoria, fires
broke out around Mt Macedon to the north of
Melbourne and in the Dandenong Ranges to the east,
with hot, dry north-westerly winds gusting up to
70 km hr -1 . Other fires developed in rural scrubland in
western Victoria and in the coastal resort strip west of
Geelong. Firefighters speedily brought under control
all but eight of the 93 fires that broke out. The cool
change, rather than bringing relief as expected, turned
the fires into raging infernos. Fire fronts were shifted
60-90 degrees and pushed forward by winds averaging
70 km hr -1 and gusting at times to 100-170 km hr -1 . The
conflagrations that swept the Adelaide and Melbourne
areas were unprecedented. Only three to four times
per century could such a combination of conditions be
expected anywhere in Australia. Even under ideal
fuel conditions, it is physically impossible to generate
fire intensities in the Australian bush greater than
60 000-100 000
biomass, boreal forests can have values up to
2 500 000 kW m -1 ). On Ash Wednesday, thousands of
houses, farms, and towns were subjected to the
maximum limit of these intensities as fires bore down
on them at velocities close to 20 km hr -1 . Aluminum
tyre rims and house sidings melted into puddles as air
temperatures reached 660°C. The intense heat gener-
ated thermal tornadoes that snapped, at ground level,
the trunks of whole stands of trees. Trees in front of the
fire exploded first into flames because of the intense
radiation and were then consumed by the maelstrom.
Such conditions had not been witnessed since the
firestorms that swept through the cities of Hamburg
and Tokyo as the result of fire bombing in the Second
World War. People fleeing in cars were outrun and
incinerated. Hundreds of people survived only by
quick thinking and luck. At McMahons Creek east of
Melbourne, 85 people escaped the inferno by shelter-
ing 30 m underground in the 1 m spacing between
water pipes servicing a dam. At the town of Cockatoo,
in the Dandenongs, over 150 townspeople survived in
the local kindergarten, in the middle of a playground as
their town burnt down around them. Along the Otway
coast, people fled to the safety of the local beaches, and
then into the ocean as the sand became too hot to bear
or wind-blasted them.
Seventy-six people died; 3500 were injured, many
with burns that would cripple them for the rest of their
lives; over 300 000 sheep and 18 000 cattle were killed;
over 500 000 hectares of urban forest and pasture burnt
in a single day; 300 000 km of fencing was destroyed;
and 1700 homes and buildings were consumed
(Figure 7.9). In South Australia alone, 40 per cent of the
commercial pine forest was burnt. Insurance claims
reached $A200 million, with total property losses
exceeding $A500 million. Channel 7's national television
news simply ended its evening program by silently
listing the 20 or more towns that had ceased to exist
that day.
The Ash Wednesday bushfires were a rare
occurrence in Australia. No modern technology, no
prescribed burning, no preparation by home-owners or
municipal councils, no improvement in prediction, no
number of firefighters or amount of equipment could
have stopped those fires from occurring nor negated
their effects. The weather conditions leading up to Ash
Wednesday were matched only by those preceding the
1939 bushfires. However, the fires exemplify the fact
that there is a weather pattern that tends to occur prior
m -1
(because of their greater
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