A submerged volcano cluster has been found 250 kilometres off the coast of Sydney.
Australia’s new ocean-going research vessel Investigator discovered extinct volcanoes during routine mapping of the seafloor in the search for the nursery grounds of larval lobsters.
‘The voyage was enormously successful, 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,’ Chief scientist for the voyage Professor Iain Suthers.
The four extinct volcanoes in the cluster are calderas, which form after a volcano erupts and the land around them collapses, forming a crater.
The largest is 1.5 km across the rim and it rises 700 metres from the sea floor.
The cluster is likely to be 50 million years old.
Professor Richard Arculus from The Australian National University, a world-leading expert on volcanoes, says these types of volcanoes are windows into the seafloor.
‘They tell us part of the story of how New Zealand and Australia separated around 40 to 80 million years ago,’ he said.
‘They’ll now help scientists target future exploration of the sea floor to unlock the secrets of the Earth’s crust,’ Professor Arculus said.
The discovery is thanks in part to the sonar technology on board the Investigator.
Previous seafloor mapping has only been possible in depths up to 3,000 metres, but the Investigator can map the seafloor at any depth.
Professor Arculus says the capability means that all of Australia’s ocean territory is now in reach.