Q&A on Australia's bushfires

Here are some key facts about the fires:

Q: Why does Australia have so many fires?

A: Wildfires are a common feature of Australia where the hot and dry weather makes the country prone to drought, which they often follow. At any time of the year, some part of Australia is susceptible to fire.

Lightning strikes are the predominant natural source of the blazes, accounting for about half of all ignitions in Australia. Fires of human origin -- lit either accidentally or deliberately -- account for the rest.

Australia's sheer size often makes the bushfires that do happen spectacular. Just one fire currently burning west of Sydney has a perimeter of more than 300 kilometres and has so far burned out over 42,000 hectares.

The worst bushfires of modern times were in February 2009, when firestorms swept through towns and hamlets in the southeastern state of Victoria, claiming the lives of 173 people.

Q: What triggered the recent fires?

A: Unseasonally hot and dry weather combined with exceptionally strong winds created the circumstances which saw more than 80 bushfires spring up across New South Wales state last week.

Reports have speculated that one massive Blue Mountains bushfire, west of Sydney, was triggered by trees bringing down a powerline in the gusty conditions, while one or two others blazes are thought to have been deliberately lit.

Q: Why is this year so bad?

A: Many temperature records around the country have been smashed in the past year and last month was the warmest September on record while the winter rainfall in New South Wales was lower than normal, meaning conditions were prime for bushfires.

This followed higher rainfall in NSW from 2009 and 2011 that caused increased growth in bush or forest areas which have now dried out -- meaning more combustible material was available to fuel any fire. In a vicious cycle, because of the warmer conditions, hazard reduction burn-offs to reduce this could not occur as necessary.

Residents of the Blue Mountains, where more than 200 homes were destroyed and scores more damaged, said the speed with which the fires threatened and then engulfed their streets was also unprecedented, helped by the strong winds.

Q: Whose job is it to tackle the fires?

A: The New South Wales Rural Fire Service is made up mostly of volunteers, with some 70,000 people from all walks of life making up the 2,000 brigades.

Prime Minister Tony Abbott is a volunteer local firefighter and worked through the night over the weekend with his brigade.

Q: How do they do it?

A: A major task of firefighters is trying to deprive fires of their fuel. During a fire, they will "backburn" -- a tactic aimed at creating firebreaks to control the path of blazes, a strategy also known as "fighting fire with fire". This is only carried out by experienced officers as part of an overall strategy.