Thursday, May 28, 2009

Victorian Fires' Intensity Equal to 1500 Atomic Bombs

By Darryl Mason

The Royal Commission into the Victorian Bushfires will hopefully lead to changes in fire management and disaster planning that will lessen the likelihood of so many Australians dying in our next, inevitable, encounter with an apocalyptic firestorm.

We are still yet to learn more about those Black Saturday rumours that claimed residents of Marysville and Kinglake were not put under a mandatory evacuation because CFA planners were more worried about evacacuees crashing their cars trying to escape (blocking roads for rescue vehicles, causing a multitude of car accidents, becoming trapped on roads swept by fire) than they were about people staying put and taking their chances. Staying put was how most Australians living in the bush have long dealt with bushfires. Not anymore.

But fire behaviour experts testifying at the commission have also made clear that the weather conditions of Black Saturday, or way the fires spread, so quickly, were anything but commonplace events. These were bushfires of unimaginable intensity and ferocity :

Black Saturday fires burned so fiercely they produced energy the equivalent of 1500 atomic bombs the size of the Hiroshima explosion - enough to power Victoria for a year - the bushfires royal commission heard yesterday.

A fire behaviour expert, Dr Kevin Tolhurst, said the best firefighting equipment could be used in direct attacks only on fires that burnt up to 4000 kilowatts a metre. He later told the Herald that some fires on February 7 burned at an intensity of 150,000 kilowatts.

Dr Tolhurst, senior lecturer in fire ecology and management at Melbourne University, also said fires could burn in an area for much longer than people are led to believe from fire-safety information, which suggested a fire-front would pass in about 10 minutes.

He said this timeframe was true of fronts, but not of "fire-activity areas" dotted with spot fires, where the area could remain dangerous to life from radiant heat for an hour or more.

Dr Tolhurst said the average rate at which fires moved on Black Saturday was about 12 kmh, but it travelled for short bursts at up to 60 kmh. Fireballs did exist, he said: "What a lot of people have seen have been fair-dinkum fireflares or fireballs."

He said these were created because the fuel on the day was so dry and the temperatures so high that burning plants gave off volatile gases quickly.

For now, the most compelling explanations for the outbreaks of the fires centre around a fallen power line, at least two alleged incidents of fires being set by CFA volunteers and a lightning strike.

ABC News keeps a dedicated page for updates from the Royal Commission here.

February 9 : A Holocaust Of Fire, Cyclone Of Flames, Burn Hundreds To Death

This Is Australia, We Burn

Wreckage - The Most Haunting Images Of The Victorian Bushfires

The Myths Of Marysville - They Died In The Church, On Their Knees, In Prayer