The search for the missing MH370 aircraft has scoured the depths of the Indian Ocean for almost a year and found no trace of the plane. While this must be heartbreaking for victims' loved ones, the search has yielded many discoveries about a part of the deep ocean scientists knew very little about.
Detailed mapping has revealed mountains as high as Mount Kosciuszko, canyons the size of the Grand Canyon and a never before seen 34-kilometre-long undersea ridge.
Geoscience Australia's Stuart Minchin said previously the only information about this region, and most of the world's deep oceans, came from satellite images that offered a coarse outline of the seafloor. Slightly more detailed information was gathered along random transect lines from the odd ship carrying a basic sonar, but combined these maps were not sufficient to guide underwater vehicles as they searched for the plane in regions as deep as 6000 metres.
From June to October the underwater surveying company Fugro hired to carry out the search deployed a ship with multibeam sonars to survey slightly more than 100,000 square kilometres.
The sonars release a series of acoustic signals shaped like a fan. The time taken for the signal to return reveals the water depth while the strength of the signal strength infers whether it has bounced off something hard or soft.
Fugro's project director Paul Kennedy said the second, more detailed phase of search used side scanners mounted on an autonomous submarine and small underwater vehicles towed about 100 metres above the seafloor. Since November they have mapped about 40 per cent of the 30,000 square kilometre priority search area. "The autonomous vehicle is searching inside a volcano at the moment," said Mr Kennedy.
In some places the estimates of the seafloor depth from satellite imagery were wrong by up to 1.5 kilometres, said Dr Minchin,chief of the Environmental Geoscience Division at Geoscience Australia.
"We've found underwater remnant volcanoes, in one case it is about 14 kilometres in diameter and 2.2 kilometres in height. Those features were invisible in the data previously," he said.
One of the most massive features they spied is a 34-kilometre-long ridge, seven kilometres wide and 1.5 kilometres high. "It was not known previously. It didn't appear in the chart," he said.
Dr Minchin said while the focus was now on the search, the data would be useful for geographers and oceanographers for many years to come.
The search area is not far from where two tectonic plates, the Indo-Australia and the Antarctic plates, meet. "What you can see on the seafloor is a history of how those plates have moved apart."
Many of the ridges are the result of two continental plates shifting and the underlying magma rising to the surface and creating new crust."It gives us a place to go looking in future to understand these processes," he said.
The data will be publicly available once the search is complete.