AS if bushfires, drought and floods aren't enough, Australians have now been warned to watch out for volcanoes.A scientist has warned an eruption is "well overdue" and says there are hundreds of volcanoes that could cause trouble, from South Australia and Victoria through to Queensland. But it doesn't seem too urgent - an eruption is already 3000 years overdue. Melbourne geologist Bernie Joyce wants "eruption response plans" drawn up.  He says there are 400 volcanoes in Victoria and South Australia, and almost as many in Queensland. "A significant eruption seems well overdue," said Prof Joyce, who has been associated with the University of Melbourne. "These geo-hazards are real and they must be given much more focus by emergency management authorities. "We can't say with 100 per cent certainty that a significant volcano will strike tomorrow, next week, next year, or even 100 years down the track."Prof Joyce takes a long-term view, as geologists tend to do. He says there has been a volcanic eruption about every 2000 years in Australia, but the last one was 5000 years ago. Prof Joyce will on Thursday be awarded the Geological Society of Australia (Victoria Division)'s Selwyn Medal.