Asked in AustraliaAustralia Natural Disasters
What caused the 2009 Black Saturday bushfires in Victoria Australia?
November 12, 2010 8:10AM
In February 2010, the Royal Commission into the Black Saturday bushfires officially blamed faulty power lines and an incorrect fitting which caused the power lines to fail, for starting the worst of the fires, the one which killed 119 at Kinglake.
Arsonists were also partially to blame, though no formal blame has been cast on them. Each place where someone's life was lost was treated as a crime scene, because the authorities said the speed with which the fires started and then took off was more likely to have occurred as a result of being deliberately lit. Fire criminologists and special investigations task forces confirmed this.
Carelessness was another cause - a lit cigarette, tossed from a passing car or truck, was blamed for starting the major bushfire that hit Bendigo, destroying 50 houses and killing two people.
At Horsham, in western Victoria, a faulty power line was found to be the cause of the fire which began in that region. Arson has, at least, been ruled out in this instance. It is believed arcing began due to a faulty insulator, resulting in showers of sparks falling to the ground and igniting the dry grass. Similarly, the survivors of the Kinglake fire, which wiped out the entire town and killed so many, launched class action as that fire also appeared to have been started by faulty power lines.
Victoria and the southern Australia region had recently experienced one of their hottest summers on record, with a heatwave over parts of Victoria and South Australia. This was on top of a drought which had lasted a dozen years. This had dried up the vegetation, making it like tinder in a fireplace - easily ignited and easily spread. Spot fires also occurred as strong, gusting winds - some hurricane-force - carried blazing embers beyond the fire fronts: these fires quickly fanned into larger fires.
Unfortunately, political pressure from "Green" groups, and red tape in DSE and CFA management had limited controlled burnoffs prior to the fire season, which would have seen a reduction in dry vegetation and fuel for bushfires.
In south-east Australia, bad fire days are associated with the presence of a 'blocking' high pressure system in the Tasman Sea. This brings hot, dry strong wind from the centre of the continent to the south-east. The high temperatures, some in excess of 45 degrees, and dry air experienced throughout Victoria on Saturday resulted in very low fuel moisture content. Combined with the extended rainfall deficit for much of the state, this resulted in tinder-dry fuel that was very easily ignited and very difficult to extinguish. In addition, to the high pressure system there was an approaching cold front which helped to strengthen winds ahead of the front, as well as causing a wind change after the front passed. Very strong winds resulted in fires that spread very rapidly with the wind and were practically unstoppable until the weather moderated following the cool change. Victoria's topography and vegetation also played a role. (A blocking high is a persistent high pressure system that occurs on a large scale, remaining stationary for a period of time, compressing and warming the air below.)
Why couldn't the fires be put out?
There is very little that can be done to suppress fires burning under these conditions. All that fire fighters can do is concentrate on asset protection and wait for the weather to change.
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