Massive Underwater Landslide Found Along The Great Barrier Reef

Debris 30 times the size of Uluru was dumped off the Queensland coast 300,000 years ago.

The remains of a massive undersea landslide have been discovered on the Great Barrier Reef, 75 kilometres off the coast of Queensland.

The main landslide cliff is several hundred metres tall, and debris from it is found scattered some 30 kilometres away, creating various knolls and smaller blocks. The place is called Gloria Knolls Slide, and was discovered by scientists working off the Marine National Facility’s blue-water research ship Southern Surveyor.

“The oldest fossil corals recovered off the top of the knoll were 302,000 years old – which means the landslide event that caused these knolls must be older,” said lead researcher Dr Angel Puga-Bernabéu.

When this landslide occurred, it would have been a spectacular event, possibly creating a phenomenal tsunami. Scientists ran a computer model which shows the tsunami was likely as high as 27 metres tall. The research was published this week in Marine Geology.

If such a landslide happened today, it’s hard to tell whether it would create as massive a tsunami, because the area is now surrounded by corals of the Great Barrier Reef.

Watch a computer-generated fly-through of the landslide.

“The impact of any resultant wave would likely be dampened significantly by the presence of the relatively modern, 9,000-year-old formation we call the Great Barrier Reef, but this remains to be assessed systematically,” said geologist Jody Webster from the University of Sydney.

After the initial discovery, there’s more to be found out about this fascinating area. Next up the researchers will need to do more mapping of the seabed, as well as gather samples to determine a more precise date of the unusual event.

Header image: North-westerly view of the Gloria Knolls Slide and Gloria Knolls off Innisfail. Depths are coloured red (shallow) to blue (deep), over a depth range of about 1700 metres.

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