A New Zealand-led group of international scientists will spend the next three weeks onboard NIWA's research vessel Tangaroa, using a free-diving robotic vehicle to investigate mineral deposits and hydrothermal activity at five major submarine volcanoes in the Kermadec Arc, northeast of the Bay of Plenty. The voyage is the first project in an international programme involving GNS Science, NIWA, and Woods Hole Oceanographic Institution (WHOI) in the United States, to explore the mineral potential of the volcanoes and their unique biodiversity.
Studies from surface ships and in submersibles during the past decade have shown some of the volcanoes in the Kermadec Arc host extensive metallic mineral deposits and one of the aims of this 25-day voyage is to clarify the type and size of these deposits.
Many of the volcanoes have highly active hydrothermal vent systems, which are home to unique biological communities of animals which thrive in the very hot and chemically-rich environments.
The five submarine volcanoes to be investigated on the voyage are Clark, Rumble II West, Healy, Brothers, and Rumble III. The nearest volcano to New Zealand is Clark, which is 150km northeast of White Island.
State-of-the-art equipment, developed by WHOI, will be used on the voyage, including a sophisticated autonomous underwater vehicle (AUV), called Sentry, and a towed digital camera system called TowCam.
The autonomous underwater vehicle, Sentry, which will be used to explore submarine volcanoes in New Zealand's Kermadec Arc during the next three weeks to survey seabed mineral deposits and investigate biodiversity around the volcanoes. Photo: Woods Hole Oceanographic Institution.
Sentry can spend up to 19 hours submerged on a single mission, before its batteries need recharging. It climbs easily over submarine obstacles and carries numerous sensors onboard, meaning it will be able to give scientists a very comprehensive picture of the volcanoes.
Sentry will be programmed to perform day-long missions to measure up to nine different physical and chemical parameters over particular areas of seabed. It can also take digital colour images of the seafloor and parts of the submarine volcanoes.
While Sentry is off on its undersea missions, scientists from GNS Science, NIWA, and WHOI will undertake other activities from Tangaroa such as photographic traverses with TowCam, dredging for rocks and minerals, collecting marine specimens from the seafloor, mapping hydrothermal plumes, and taking gravity and magnetic measurements.
These complementary investigations will effectively double the productivity of the voyage.
"Having an autonomous underwater vehicle will substantially increase the amount of data we collect for the number of days we are at sea," said Project Leader, Cornel de Ronde of GNS Science.
"Sentry is the world's best autonomous underwater vehicle for geological applications and it will enable us to recover about twice the normal amount of information for a voyage of this duration," Dr de Ronde said.
The mission will characterise the different seafloor venting systems to determine the relationship between depth of the volcano, volcano type, type of venting, and the type of mineral deposit being formed.
NIWA Principal Scientist, Malcolm Clark, said research activities during the voyage would be very complimentary.
While some of the scientists would be improving their understanding of the size and distribution of potential mineral resources, others would be learning more about marine life and the environment around the volcanoes.
"That really gives us the full spectrum of information and evidence to make future decisions on."
The submarine volcanoes in the study vary in depth from 200m below the surface to 1.8km depth. They are all large volcanoes, ranging from one which is similar in size to Mount Ngauruhoe to one which is larger than Mount Ruapehu.
The data gathered during the voyage would keep scientists busy for up to two years as they analysed it and produced reports and scientific papers, Dr de Ronde said.
Research vessel costs for the voyage are being met by Land Information New Zealand, and supplemented by NIWA.
Scientists on the voyage come from New Zealand, the United States, Australia, and Switzerland.
Note: Sentry is the world's most sophisticated autonomous underwater vehicle for marine geology applications. Battery-powered and weighing 1.25 tonnes, it is capable of diving to 4500m and spending up to 19 hours under water per mission. This allows it to operate up to 100km from its mother ship. It has four pivoting wings with a propeller on each wing. It can travel at 2.3 knots and is equipped with up to 10 science and engineering sensors to measure physical and chemical parameters of the ocean and seafloor. All sensor data is stored on the vehicle and retrieved on recovery. This voyage is Sentry's first application in New Zealand. Woods Hole Oceanographic Institution in the United States owns and operates Sentry.