Mapping Australia’s sea floor

By Jenna Hanson 7 November 2013
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Scientists are finding out more about the unknown frontiers of the sea floor with 3-D mapping technology.

COVERING NEARLY 71 PER CENT of the world and supporting nearly half of the world’s species, the ocean is a mysterious and exciting world that’s one of the remaining little-explored frontiers.

Only a minute amount of the sea floor has been mapped despite the fact that it plays an integral role in many of the Earth’s systems including climate and weather.

“Google Earth has just updated their ocean terrain data and they say about 15 per cent of the globe is well mapped,” says marine geologist Dr Rob Beaman from James Cook University in Townsville, Queensland. “Within Australian waters, it’s probably about the same figure.”

Mapping the Coral Sea

According to Rob, Australian waters are not well mapped because of a lack of sonar technology available in here. While the technology has existed for many years, Australia’s surveying capability has been held back by the limited resources; there’s only one vessel available with deep-water multi-beam sonar.

“We just don’t have the full capability to survey down to the deepest reaches of Australia’s seafloor, which can be over 5000 metres deep,” says Rob. “Australia has often had to rely on the goodwill of passing foreign research vessels with this type of sonar to do the surveys for us.”

However, this good will only goes so far, with surveys only producing strips of data, not the systematic mapping of wider areas that Rob feels is important.

“That said, the replacement Marine National Facility, RV Investigator will have a full range of sonar systems that will finally allow Australians to map the full range of ocean depths found within our own waters,” says Rob.

New discoveries of the Coral Sea

Rob has put the available technology to good use, working with the Australian Hydrographic Office and Geoscience Australia, the Queensland Government and the Reef and Rainforest Research Centre to expand on his previous research mapping parts of the Great Barrier Reef closer to the Australian coast, to create new detailed maps of the reefs, mountains, and canyons in the Coral Sea.

The maps reveal a large number of underwater canyons in the area, as well as 14 underwater mountains, or seamounts, rising at least 1000 metres from the sea floor. “One seamount, the Fraser Seamount, is 4060 metres high, nearly twice the height of Mt Kosciuszko, Australia’s highest mountain,” says Rob.

“I feel very fortunate to be able to reveal the seafloor in the Coral Sea.”

Rob also loves looking at data from the high-resolution 3D methods, called ‘lidar’ or satellite bathymetry. “This technique is ideal for deriving depths over coral reefs or other shallow-water environments that are difficult to survey with boats,” says Rob. “I am always amazed at the fine-scale complexity of coral reefs, simply created through time by such tiny organisms.”