In the firing line

Australian volcano eruptions overdue, new study confirms

Using the latest dating techniques, scientists from the University of Melbourne’s School of Earth Sciences and the Melbourne School of Engineering have calculated the ages of the small volcanoes in the regions and established the recurrence rate for eruptions as 2,000 years.

With the last volcano eruption at Mt Gambier occurring over 5,000 years ago, scientists say the areas are overdue...

“Although the volcanos in the region don’t erupt on a regular sequence, the likelihood of an eruption is high given the average gap in the past has been 2,000 years,” Professor Joyce said.

“These are small eruptions and very localised but depending on the type of eruption, they could cause devastation to thousands of people,” he said.

The regions of Western Victoria and adjacent south-eastern South Australia demonstrate a history of activity by young monogenetic (single short-lived activity) volcanoes. Similar young monogenetic provinces are found in northeast Queensland.

Professor Joyce suggests it might be a good idea to local governments to think about what to do if an eruption takes place, as they do in Auckland.

Which reminds me, I recently heard on the Science Show a brief mention of Auckland's Rangitoto Island, which only formed in an eruption 600 years ago. (I've been there once, many years ago, but I remember it as very pretty.) As this New Zealand site explains, it's an area absolutely ripe for a new volcano that could come through anywhere:

All of Auckland’s volcanoes come from one magma source. Underlying Auckland is a diffuse pool of magma that occasionally finds its way to the surface. Unlike a ‘classic’ volcano – such as Mt Taranaki or Mt Ngāuruhoe with a single vent through the crust – in Auckland, the magma finds different routes through the crust and erupts in a different place each time.

Each volcanic cone in Auckland stems from a separate eruption from the pool of magma that lies under the city. It’s unlikely that the magma will push through in the same place twice, so each volcano that can be seen on today’s landscape can be thought of as dormant. However, the underlying magma is still active – it may come through at a new place and form a new cone next week, next year or next century.

Obviously, the town planners who let the city be built there have a lot to answer for! :)