Tsunami risk on the Reef
RESEARCHERS have discovered the potential collapse of a sediment block deep underwater off Cairns would generate a tsunami carrying waves of up to 11m high.
While it would take a "catastrophic" earthquake for the large block to collapse, the resulting tsunami would take just over an hour to travel the 70km to shore, hitting Clump Point, near Mission Beach first.
James Cook University scientist Dr Robin Beaman was part of the team who made the discovery while carrying out 3D mapping of deep parts of the Great Barrier Reef recently.
The scientists found the site, dubbed the Noggin block, already shows signs of collapse due to erosion caused by sediment falling from the reef above.
The block, about 100km southeast of Cairns, is between 340m to 470m deep and measures one cubic km.
Age-date testing on deep water corals growing on the block show it is thousands of years old.
Dr Beaman said the block was currently stable and it would take a catastrophic event for it collapse such as an earthquake measuring more than seven on the Richter scale.
"It would take a trigger like a large earthquake which would shake it loose ... which is really unlikely," he said.
"The risk is very low.
"We stress that this is only a modelled scenario and not a cause for alarm for the communities along the North Queensland coast."
Researchers are now planning on sending underwater robots to investigate the area, while continuing to map parts of the Reef to identify other areas that might collapse.
The research, which was carried out with Spain's University of Granada and the University of Sydney, has been published in the Natural Hazards journal.
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Danger zone: 3D mapping of deep parts of the Great Barrier Reef.