The state-of-the-art 116m German research ship Sonne has started a month-long voyage off the Hawke's Bay and Poverty Bay coasts investigating links between seafloor gas vents and underwater landslides.

Slow-moving under-sea landslides have been identified in the waters and scientists wish to investigate links between seafloor gas vents and submarine landslides.

Stuart Henrys is one of two GNS Science marine geophysicists in the joint German-New Zealand voyage.

"We are hoping to recover landslide material to see if gas hydrates are part of the rock mixture on the seafloor," he said.


"We have geologists on board to describe the sediment we recover. We also have geochemists to analyse the sediments to detect any traces of gas hydrates," says Dr Henrys.

The Sonne, the flagship vessel of the German research fleet, is capable of drilling 200m below the seafloor to retrieve samples for analysis. It was launched less than two years ago and is booked for the next three years for research projects. The voyage is part of an ongoing international effort to understand the geology of the seafloor off the East Coast, where where the Pacific Plate is dragged under the Australian Plate in the Hikurangi Trench.

The Hikurangi Trench subduction zone lies less than 100km off the coast and runs south to the waters off Kaikoura.

It has some of the most extensive deposits of a frozen form of methane in the world, with the potential to be New Zealand's main source of natural gas for decades.

Small ocean temperature changes could cause the deposits to lose structure, triggering movements in the ocean floor.

A sudden landslide or earthquake in the trench has the potential to create a devastating East Coast tsunami. A similar zone caused Japan's devastating magnitude-9.0 earthquake and tsunami in 2011.