Underwater canyon mapping reveals more seafloor secrets

Underwater canyon mapping reveals more seafloor secrets

This diagram shows cross-section views of the Moeraki/Haast channel system.

NIWA scientists have completed another successful voyage to the west coast of the South Island to study the enormous underwater canyon system in the area.

During the 15-day voyage, RV Tangaroa crossed the canyons region collecting mulitbeam bathymetry to map two tributary systems of the Cook/Hokitika canyon system and an additional 400 kilometres of the Moeraki/Haast canyon system. This mapping follows previous voyages in 2005 and 2007 which revealed a vast network of canyons in the area, many times larger than the Grand Canyon.

The research, funded by the Foundation for Research, Science and Technology,is investigating how changes in climate affect the type and amount of sediment that ends up in the ocean.

Our new mapping shows the Cook/Hokitika system is characterised by narrow, 400-metre-deep channels that transport silty mud to the deep ocean. In contrast, the Moeraki/Haast channel system is up to eight kilometres wide. These two channels converge at a depth of more than three kilometres, dropping much of their gravelly load on the seafloor. The outer edges of the canyon system have not yet been reached but another voyage is planned next year.

Research subject: Oceans