Underwater landslides may have triggered tsunamis off Fraser

EVIDENCE has been found off Fraser Island of ancient underwater landslides that had the potential to create tsunamis.

EVIDENCE has been found off Fraser Island of ancient underwater landslides that had the potential to create tsunamis.

Researchers from the University of Sydney found the evidence while mapping deep-sea canyons between the Fraser Coast and Yamba in northern New South Wales.

Associate Professor Tom Hubble said the data showed most of the landslides probably occurred at least several million years ago and could be even older.

"The circumstance needed to trigger one of these landslides is a moderately large and shallow earthquake measuring more than 6.5 or 7 on the Richter Magnitude Scale, which might happen once every 5000-10,000 years in south-eastern Australia," he said.

The researchers are investigating how often the underwater landslides have occurred and their potential triggers.

Dr Hubble said substantial data was collected around Fraser Island on the three-week voyage thanks to the region's unique seafloor.

"There is a significant canyon not too far from the coastline, which creates an upwelling and attracts a wide range of marine species to feed on the nutrient-rich waters," he said.

The researchers also visited the region in 2008 to collect preliminary data on the landslides and underwater erosion.

On this voyage, which finished on February 4, researchers collected sediment cores and rock samples from new sites and expanded the area of seafloor mapped in detail.

Underwater landslides

• Similar research in the Great Barrier Reef found landslides occurred up and down the coast.
• Researchers used a multi-beam echo-sounder to map the sea floor down to three kilometres below the surface of the sea.