Geoscientists unravel Australia’s volcanic mystery

Geoscientists from the University of Sydney have uncovered why Eastern Australia has been dotted with hundreds of ancient volcanoes.

Australia is a stable continent with volcanoes being a non-existent threat in modern times.

However, the remains of volcanoes can be found across the country’s east coast with many eruptions occurring across the past 80 million years.

According to Dr Ben Mather, of the University of Sydney’s School of Geosciences, Australian volcanoes are one-time events, with their remnants looking similar to regular hills such as Cradle Mountain in Tasmania.

“Rather than huge explosions like Krakatoa or Vesuvius, or iconic volcanoes like Mount Fuji, the effect is more like the bubbles emerging as you heat your pancake mix,” Dr Mather said.

He said the east coast of Australia has a mix of molten rock that bubbles to the surface through the crust of the continent.

“Under our east coast we find a special volatile mix of molten rock that bubbles up to the surface through the younger, thinner east coast Australian crust,” Dr Mather said.

The study, which was published in Science Advances observed how eruptions occurred from North Queensland to Tasmania and in the mostly submerged continent of Zealandia.

Rather than being caused by tectonic plates, peaks in volcanic activity were caused by a high volume of sea floor material moved under the continent from the east by the Pacific tectonic plate.

According to the study, this is known as “subduction”, where material is pushed under Australia’s continental shelf, where it then re-emerges as volcanic eruptions along the younger and thinner east coast of Australia.

“What sets the East Australia-Zealandia region apart is that the sea floor being pushed under the continent from the Western Pacific is highly concentrated with hydrous materials and carbon-rich rocks,” Dr Mather said.

“This creates a transition zone right under the east coast of Australia that is enriched with volatile materials.”