THE investigation into the blaze that burned 500ha of bushland west and north of Coolum Beach has not determined how the devastating fire started.
What Queensland Fire and Emergency Services fire investigator Geoff Hunter did find was that three fires were started near Stumers Creek on January 19.
"The first crew went to Cinnamon Park, there were two seats of fire there in grassland, east of Stumers Creek," he said.
"Once crews extinguished those fires they noticed a fire on the other side of Stumers Creek about 60m away."
It was this third fire, which started 30m from a track in bushland in the southern end of Noosa National Park, which spread quickly, burning hundreds of hectares of land, and forcing the evacuation of homes and the closure of roads.
A taxi driver passing close to Cinnamon Park reported seeing smoke and youths leaving the area around the time the fire was started, but Mr Hunter said nothing had been found during the investigation to indicate how the fires started.
"I didn't find anything I could put down as an ignition source; nothing was found," he said.
"There had been no lightning strikes.
"The cause is undetermined but we can't rule out human intervention.
"Whether it was accidentally or deliberately lit, who knows."
Shovels and pots, mesh and plants were found in the bushland area where the fire started, suggesting people might have been visiting the area, Mr Hunter said.
He said it was possible that embers had jumped from the first two fires and started the third, but it was unlikely.
OUT OF CONTROL
THE fire-danger rating was high on January 19.
"The fuel load was about 15-20 tonnes per hectare; that's quite thick," Mr Hunter said.
"The combination of the fairly-strong south-easterly wind and the fire-danger rating, the Keetch-Byram Drought Index (a moisture assessment tool) and the fuel load all aided to push it through the bushland quite quickly."
This fire burned west from Stumers Creek, jumped the Sunshine Mwy and spread to the west and north, burning for days.
Homes were evacuated at Yandina Creek, Verrierdale and Peregian Springs, but none were lost.
With dry conditions persisting and the early beginning of the bushfire season, Mr Hunter said people must take care around bushland.
"We have to be mindful of possible ignition sources around bushland," he said.
"It's really dry at the moment and, like with the bushfire we saw two weeks ago at Caloundra, if the wind gets behind it it can cause a lot of spot fires."
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