How scientists accidentally discovered 50-million-year-old underwater volcanoes

Geoscientists say this cluster of four extinct volcanoes could be the first of many surprising underwater discoveries, thanks to powerful new technology. 

Paul Muir/Queensland Museum/Handout/Reuters
Reef corals are seen in the Western Indo-Pacific Ocean in this undated handout picture from Paul Muir from the Queensland Museum in Townsville, Queensland, Australia.

Don’t you just hate it when you go looking for baby lobsters and stumble upon a cluster of 50-million-year-old volcanoes?

In an unexpected turn of events, a team of 28 researchers recently discovered four ancient underwater calderas – giant craters that form after land collapses in a volcanic eruption – about 155 miles off the coast of Sydney, Australia. 

The largest caldera is nearly a mile across at the rim and rises 2,300 feet (almost half a mile) from the seafloor. 

The accidental discovery occurred during a routine mapping of the ocean floor on the last night of the 15-day voyage, which was intended to search for lobster nursery grounds. 

“My jaw just dropped,” said marine biologist Iain Suthers, the chief scientist for the voyage, to The Guardian. “I immediately said, ‘What are they doing there and why didn’t we know about them before?’ It really backs up the statement that we know more about the surface of the moon than our sea floor."

Scientists believe the volcanoes, which lie about 16,000 feet beneath the surface of the ocean, were created during a series of shifts in tectonic plates that caused Australia to rift from New Zealand around 40 to 80 million years ago. The area was previously thought to be “billiard-table flat,” Professor Suthers said.

So how did such massive structures go unnoticed for so long? 

According to volcanologist Richard Arculus, the sonar on Australia's previous research vessel, Southern Surveyor, could map the sea floor only to around 10,000 feet, leaving half of Australia's ocean floors out of reach. 

But on the Investigator, the new vessel used for the lobster larvae research, "We have sonar that can map the sea floor to any depth, so all of Australia's vast ocean territory is now within reach, and that is enormously exciting," Professor Arculus said in an Australian National University press release

He says these newly discovered volcanoes will "help scientists target future exploration of the seafloor, to unlock the secrets of the Earth's crust." 

The Australian government funds Investigator for 180 days, and scientists hope that this discovery will encourage legislators to support year-round funding. 

"With these sorts of discoveries, they'll see it's crazy to have it tied up to the wharf," Suthers told the Sydney Morning Herald. "If we just found these volcanoes by chance chasing larval lobster, imagine what we could find with a dedicated survey."

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