Modelling shows what could happen if between Melbourne and Mount Gambier volcanic chain erupts

A sneak peak … Mount Gambier’s Blue Lake is the most prominent feature of the region’s volcanic chain. Source: News Limited

In fact the Mount Gambier volcanic chain erupted a mere 5000 years ago – a blip in the world of geophysics – and volcanologists believe a similar event could rival the 2010 volcanic eruption in Iceland in terms of impact.

The news follows the revelations earlier this week that the magma basin underneath Yellowstone National Park in the United States was two and a half times larger than previously thought, leading to new predictions about the damage it could cause in an eruption event.

Dr Jozua van Otterloo and Professor Ray Cas from the School of Geosciences at Monash University used modelling to show the last known eruption of the Mount Gambier volcanic chain would have been a size four eruption on the Volcanic Explosivity Index (VEI) – equivalent to Eyjafjallajökull, the Icelandic peak which went up in 2010, grounding aeroplane traffic in many parts of the world.

A shadow cast on the planet … the grey areas represent the spread of the ash from the Eyjafjallajökull volcanic eruption in Iceland in 2010. Scientists believe the Mount Gambier eruption of 5000 years ago would have been of a similar size. Image: Monash University Source: Supplied

Dr van Otterloo said Australia could face the same scale of tragedy if the Mount Gambier chain were to erupt.

“Little is known about the magnitude of eruptions from this volcanic province (the Newer Volcanics) that stretches around 400 kilometres between Melbourne and Mount Gambier. It has over 400 eruption centres and has been active for at least 4 to 5 million years,” he said.

“Normally the size and magnitude of eruptions of active volcanoes are determined based on observations during these eruptions. Using 3D geometrical modelling, we’ve shown it is also possible to obtain volume estimates for different deposits of a prehistoric, monogenetic volcanic centre.”

Ol’ blue eyes … Mt Gambier’s gorgeous lakes are a product of the region’s active geophysical history. Picture: Frank Monger Source: Supplied

The team produced a diagram showing the impact of ash plume as it dispersed from the 2010 Iceland eruption over Europe, but juxtaposed over Australia with the eruption in Mount Gambier.

The team believe the eruption that took place 5000 years ago would have produced an ash plume 5-10km high and displaced material equivalent to the volume of 130,000 Olympic-sized swimming pools.

“Magma rose to the surface from a depth of 80 kilometres and a large part of that magma interacted with the shallow groundwater which made the eruption so violent,” Dr van Otterloo said.

Volcanic aftermath … Rock formations at Cape Duquesne, near Portland in Victoria (100 kilometres from Mount Gambier), were formed by lava flows meeting the sea. Picture: Monash University Source: Supplied

And when could the chain erupt again? Nobody knows.

“When and where the next eruption will occur is unknown,” Dr van Otterloo said.

“That is why our team continues undertaking extensive research in the area. Although statistics tell us it could be a long time before the next eruption, the main hazard is that when it does, we will only have a few days warning.”

Dr van Otterloo said a similar eruption in the region would cause closure of the major airspace of eastern Australia, health risks from fine ash composed of glass fragments, destruction of crops and impacts on livestock up to 100 kilometres from the erupting site and disruption to local infrastructure.

“Understanding explosive volcanism aids the community to manage risk and provides insight into potential regional or global disruptions including to infrastructure, and impact on climate,” Dr van Otterloo said.

The Monash team published their findings in the Bulletin of Volcanology.

Pretty, but with a hell of a temper … the steep banks of Mount Gambier’s Blue Lake are actually the sides of the volcanic crater. Source: Supplied