Ember attack
An ember attack is when, during a bushfire, burning twigs, branches or leaves become temporarily airborne and are carried by winds in a cluster.
The Stringybark species of Eucalypt is particularly notorious for contributing large flaming sections of bark that due to their size, weight and shape, can be carried up to several kilometres away. The movements of embers from a bushfire are the primary cause of spot fires, which contribute to the continued spread of a bushfire.
Ember attackes mainly occur close to the source of the fire, usually following a heat explosion within vegetation in which material is ejected from the explosion and creates a cluster of embers, or during high winds in which burnt material is carried away from flames before it can be fully combusted. In dark conditions, an ember attack can leave a small light trail similar to that of a camera set to a long exposure time.
Effect on firefighting
Ember attacks have the potential to start small fires ahead of the main fire trapping firefighters between the two fires. They can also lodge themselves within firefighting equipment, clothing and vehicles.
In late 2019, a fire truck caught fire in an ember attack in the Currowan bushfire in New South Wales, Australia.[1] Fortunately, the fire team made it out alive. Ember attacks are particularly dangerous to an individual's exposed skin and face.
Effect on property
If an ember lands on a particularly combustible object such as a housemat or a garden bush, or several such embers hit the house within a period of time (or even enter through a timber framed window or vent), they may ignite parts of the house and eventually cause the entire house to burn down.
Because embers can be carried away from a bushfire by the wind, they pose a threat to houses that one would intuitively assume are far enough away from the fire. Fire authorities advise vigilance by home owners before and after a fire front passes. Embers can ignite combustible materials outside the home. A danger also exists of embers entering the home, in particular the roof space, requiring occupants to inspect for signs of fire in the roof.
In Australia, evaporative air conditioners are known to ignite from ember attack. Ember attack causes the filter pads from evaporative AC to ignite, and the fire spreads through the roof space destroying the home. Ember guards (also known as ash screens) are recommended to protect air conditioners from ember attack.
References
- Siganto, Talissa (1 January 2020). "Firefighters survive after being trapped in burning fire truck during ember attack".