A huge slab of sea floor near the Great Barrier Reef is in the early stages of collapse and could trigger a tsunami, researchers have warned.
Marine geologists from Australia’s James Cook University have been using advanced 3D mapping techniques on the deepest parts of the reef since 2007 and have discovered dozens of sub-marine canyons.
On a recent trip, they found a one cubic kilometre slab of sea floor – the remains of an ancient underwater landslide – which is perched on the continental shelf.
Geologist Robin Beaman said: “Under-sea landslides are a well understood geological process, but we didn’t know there were any on the Barrier Reef.
“It is sitting on top of a sub-marine canyon, cutting into the slopes and it is in the preliminary stage of collapse.”
He added that it was unclear when the collapse would occur.
Mr Beaman said: “It is slowly giving way although it remains stable under current conditions.
“But it is absolutely going to collapse and when it does it will fall one kilometre into the adjacent basin.
“We’re not trying to alarm people, but we need to know it is there and what could happen when it falls.”
The discovery, published in the journal Natural Hazards, was made by geologists on board the research vessel Southern Surveyor.