"When and where the next eruption will occur is unknown," says Jozua van Otterloo. "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." (Credit: David Hewett/Flickr)

In Australia, volcano’s past sounds alarm about next eruption

If the Mount Gambier volcano in Australia were to erupt with the same magnitude that it did 5,000 years ago, it’s impact would reach as far as 60 miles away from the eruption site.

Scientists used 3D geometrical computer modeling and thermodynamics—the study of the relationship between different forms of energy—to determine the size and magnitude of the Mount Gambier eruption.

It is believed to be the first time the magnitude and size of a volcano on Australian mainland has been calculated, based on volume estimates of the volcanic deposits, and modeling of the volcanic plume, ash-dispersal, and thermodynamics.

Australia’s most recently active volcano registered as a size four eruption on the Volcanic Explosivity Index (VEI)—a similar size to the Eyjafjallajökull, Iceland eruption in 2010, which caused global chaos. Australia could face the same scale of tragedy if a volcano west of Melbourne was to erupt.

“Little is known about the magnitude of eruptions from this volcanic province (the Newer Volcanics) that stretches around 400 kilometers between Melbourne and Mount Gambier,” says Jozua van Otterloo of the School of Geosciences at Monash University. “It has over 400 eruption centers and has been active for at least 4 to 5 million years.

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

130,000 Olympic pools

For the study, published in the Bulletin of Volcanology, 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.

It was shown that the amount of material dispersed during the Mount Gambier eruption was equivalent to the volume of 130,000 Olympic pools.

“Magma rose to the surface from a depth of 80 kilometers (50 miles) and a large part of that magma interacted with the shallow groundwater which made the eruption so violent. With an ash plume of at least 5 to 10 kilometers (3 to 6 miles) high, the eruption can be classified as a size four eruption on the Volcanic Explosivity Index (VEI),” van Otterloo says.

“When and where the next eruption will occur is unknown. 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.”

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 kilometers (62 miles) from the erupting site and disruption to local infrastructure, van Otterloo says.

“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.”

Source: Monash University