According to researchers, the natural calamity might have occurred almost 3,00,000 years ago due to a strong quake. The total volume of the landslide debris was approximately 32 cubic kilometers or roughly "about 30 times the size of Uluru"-or Ayers Rock-the massive 348-m-high monolith".
The researchers discovered the ancient landslide while conducting 3-dimentional mapping of the Queensland Trough's ancient reefs.
This ancient landslide complex - called the Gloria Knolls Slide - is what remains after a huge amount of sediment that once made up Australia's continental shelf broke off in a violent undersea collapse that took place more than 300,000 years ago.
"We'd like to know more about the deep animals of the Great Barrier Reef because, yes, the shallow water corals are all very important, but we want to understand about the deep marine life too", Beaman said. The smaller blocks lie scattered over an area of about 30 km and at a depth of about 1,350 metres. "We believe an natural disaster of sufficiently large magnitude was the most likely trigger for such a landslide event", study researcher Robin Beaman of James Cook University in Queensland, Australia, told Live Science in an email.
The scientists have analyzed the data and reported that the impact of a tsunami would have been significantly offset by the presence of coral reefs.
'In an area of the Queensland Trough that was supposed to be relatively flat were eight knolls, appearing like hills with some over 100m high and 3km long'. The Great Barrier Reef is at severe risk due to the burning of coal as well.
That time was at least 300,000 years ago, he said, because coral fossils collected from the knolls went back that far, and the landslide would have predated them.
The landslide was a "catastrophic collapse" that pushed debris about 20 miles from the base of the slip, Beaman said.
"This is a major step forward in understanding how seaweeds can harm corals and has important implications for comprehending the consequences of increased carbon dioxide emissions on the health of the Great Barrier Reef", Associate Professor Diaz-Pulido said. In one of the knolls, the team discovered a community of both living and fossilized cold-water corals, mollusks and barnacles, which played an important role in dating the ancient event.
Already the team of worldwide researchers have been surprised by the marine life they have found in the deep-sea conditions where temperatures can drop to 4 degrees Celsius and it is pitch black.