Volcano cluster thought to be 50 million years old accidentally discovered off coast of Sydney

Updated

Four extinct volcanoes likely to be 50 million years old have been accidently discovered about 250 kilometres off Sydney's coast.

Australian research vessel Investigator found the volcanoes nearly five kilometres under the ocean surface while searching for nursery grounds for larval lobsters and fish.

It was an exciting, serendipitous discovery, according to voyage chief scientist Professor Iain Suthers, from the University of New South Wales.

"There on the screen were these four incredible volcanoes looking like something off the front cover of a geology textbook... if you could drain the ocean it would be magnificent to see for a few seconds, it's a remarkable structure," he said.

"Now all of Sydney, all of Australia have it as part of their claim of the sea floor and we never knew it was there."

The volcano cluster is 20 kilometres long and six kilometres wide.

The largest is 1.5 kilometres across and rises 700 metres from the sea floor.

They formed after eruption when the land around them collapsed to form a crater.

Ancient volcanoes reveal secrets of Australia formation

The volcanoes have been described as "windows to the sea floor".

"They tell us part of the story of how New Zealand and Australia separated around 40-80 million years ago," said the Australian National University's Professor Richard Arculus, a world-leading expert on volcanoes.

"They'll now help scientists target future exploration of the sea floor to unlock the secrets of the Earth's crust."

He said the research vessel before Investigator could only map the sea floor to 3,000 metres.

"Which left half of Australia's ocean territory out of reach," Professor Arculus said.

"The exciting thing for all of us is that for the first time we have a research vessel that can access almost the full range of ocean depth, so we can map the sea floor.

"Suddenly, you turn a light on in a darkened room and, wow."

Investigator research ship could make more deep-sea discoveries

The voyage also led to the discovery of the abundance of larval fish and lobster far off the coast, Professor Suthers said.

"Not only did we discover a cluster of volcanoes on Sydney's doorstep, we were amazed to find that an eddy off Sydney was a hotspot for lobster larvae at a time of the year when we were not expecting them," he said.

"You'd never expect to find large healthy Yellowfin Bream inside an eddy over 100 kilometres off the Central New South Wales coast.

"But we did, and we found lots of them."

Professor Suthers said the Investigator had capabilities that marine scientists in Australia had never had before, and that discoveries with the craft were limitless.

"This is the first time we have been able to respond directly to the changing dynamics of the ocean, and for a biological oceanographer like me, it doesn't get more thrilling," he said.

"It's a whole new way of understanding the effect of climate change, the strength of the East Australian Current and what the future may hold for our grand children."

The research voyage is carrying 28 scientists from UNSW, Latrobe University, the University of British Columbia, the University of Sydney, the University of Auckland, the University of Technology Sydney and Southern Cross University.

Topics: science-and-technology, academic-research, environment, sydney-2000, australia, newcastle-2300, gosford-2250

First posted