Niwa research vessel Tangaroa left Wellington on Saturday and its three scientists and 13 crew will spend two weeks mapping about 25,000sq km of seabed from North Otago to the Catlins. A further 25,000sq km will be surveyed within the next 12 months.
They will use a multi-beam echo sounder and sub-bottom profiling to create a highly accurate digital terrain model of the seabed, showing its depth below the surface and the materials it is composed of. The echo sounder also has the ability to identify and track significant gas plumes in the water column, which indicate escaping gas.
Niwa research general manager Dr Rob Murdoch, who is not on Tangaroa, said yesterday the voyage was part of a 15-year programme, established in 2004, that aimed to provide New Zealand with better knowledge of its ocean territory.
Because New Zealand had so much seabed to map, government agencies had to prioritise the areas that should be surveyed first.
The Otago coastline had been pushed up the list because of interest from oil companies, he said.
While oil companies carried out their own seismic surveys, the Niwa survey would provide a "fundamental baseline" and a physical context for any planned exploratory oil drilling in the future, Dr Murdoch said.
"Potentially, this is an important region for oil and gas exploration. As such, there is a need to better map the region ...
This will also help provide a basis for environmental management should oil and gas development in this region proceed."
Tangaroa would work outwards from the edge of the continental shelf, about 20km offshore, he said, focusing on the undersea Bounty Trough and the network of canyons that fed into it. The trough heads out to sea almost at right angles from Otago Peninsula.
The data collected would aid the design of possible future oil rig anchoring systems, Dr Murdoch said. It would also enhance the geophysical knowledge and natural hazard assessments of the area for nautical charting, important for maritime safety, oceanography and tourism.
Later, Niwa hoped to carry out a more detailed assessment of the marine life in the Bounty Trough area.
The data would be available to everyone, including oil companies, Dr Murdoch said.
