Two new series of extreme wildfire burns was completed near Twizel in autumn 2023, as part of Scion’s Extreme Fire research programme.

The burns follow on from experimental burns of stubble and gorse. This time a first series of burns involved burning radiata pine slash close to three commonly used types of house-cladding to test the vulnerability of the cladding to radiative heat; also to test new instrumentation.

A second series of nine experimental burns of various sizes were then completed, where the team achieved the objective of creating ‘fire whirls’ or fire tornadoes. Fire whirls occur during extreme fire events and creating them outside the lab with forest fuels was a world-first. The whirls are usually caused by a combination of fuel and landscape, but in this case piles of slash were shaped to cause the whirls to form and enable scientists to monitor and measure them.

Preliminary analyses have confirmed that the shape of fuel piles can greatly influence the build-up and intensity of fire whirls – information that will help predict wildfire behaviour.

Collaborators: University of Canterbury, US Forest Service, US National Centre for Atmospheric Research, Hexion,Fire and Emergency NZ, Department of Conservation.