THE Black Saturday fires burned so fiercely they produced energy equivalent to 1500 of the atomic bombs used on Hiroshima, enough to power Victoria for a year, the Bushfires Royal Commission heard yesterday.
Fire behaviour expert Dr Kevin Tolhurst said the best fire-fighting equipment could be used in direct attacks only on fires that burned up to 4000 kilowatts a metre. He later told The Age that some fires that day burned at an intensity of 150,000 kilowatts.
Dr Tolhurst, senior lecturer in fire ecology and management at Melbourne University, also said that fires could burn in an area for much longer than what people are led to expect from current fire-safety information, which suggested a fire front would pass in about 10 minutes.
He said this time frame 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.
Analysing footage of the Murrindindi fire, he said: "There is a period here of basically half an hour where the radiation level would be very high, and an hour where the fire activity is quite pronounced … so it is … probably an hour where it would be dangerous."
He said the average rate at which fires moved on Black Saturday was 12 kilometres an hour but because fire "pulsed" forward, it could travel for short bursts at up to 60 kilometres an hour.
Fireballs did exist, he told the commission: "What a lot of people have seen have been fair dinkum fire flares or fireballs."
He said these were created because the fuel on the day was so dry and the temperatures were so high that burning plants gave off volatile gases quickly.
The gases moved through the air faster and then ignited into huge balls when they reached clearer air at the edge of the fire. "You only need to go down to Southbank to see the gas flares in front of the casino there. It is the same phenomenon," he said.
The winds that were created by the fires were so fierce that tree trunks snapped, he said.
Dr Tolhurst spent much of Black Saturday working at the Integrated Emergency Control Centre (IECC), where agency chiefs ran the response to the fires.
He and his colleagues drew up several maps predicting that the fires would reach Marysville and Kinglake, which CFA chief Russell Rees has previously told the commission he did not see.
Marysville was razed and lost 38 people, and 120 died in the Kinglake ranges.
Dr Tolhurst said his team used to sit in a room directly off the control centre, but from January had been moved to a back room, where it was harder to monitor events.
"It meant that we weren't getting any or very much casual information. It was only when either we ventured into the IECC or someone came into our room that we had a direct connection with what was happening."
He said a fire prediction map could be drawn up within half an hour if all the information it relied on was already available, but it had taken up to four hours on the day as necessary facts were hunted down.
Electronics engineer Simon Langdon told the commission he had developed a system of remote-controlled cameras that were being trialled in four bushfire areas. He showed footage of the Murrindindi fire from a camera on a tower.
Mr Langdon said the system could zero in on a target such as a smoke plume and estimate its position by latitude and longitude — or street address — within a minute.
Mr Langdon said it was hoped the system could be linked into phone number databases so that warnings of fire could be sent to all telephones in an affected area.
