JOIDES Resolution heads to Antarctica

HARD AT WORK: Scientific research ship the JOIDES Resolution has a series of expeditions in New Zealand over an 18-month period, including drilling into the sea floor off the coast of Gisborne to help scientists learn more about the Hikurangi subduction zone and slow-slip events. JOIDES stands for Joint Oceanographic Institutions for Deep Earth Sampling. Picture supplied

ONE of the world’s top scientific research ships has just concluded an investigation into the Hikurangi subduction zone. The 140m JOIDES Resolution has been off the coast of Gisborne for six weeks.

The ship drilled between 200 and 750 metres into the sea floor at six locations, ranging from 30km to 100km east of Gisborne, investigating the Hikurangi subduction zone.

This subduction fault is known internationally for slow-slip events. This is a type of slow, creeping movement in the fault beneath the sea floor.

It involves small bursts of movement on the fault lasting from weeks to months, instead of seconds to minutes as in conventional large earthquakes.

Slow-slip events are not well understood, and scientists want to know what causes them and what relationship they have with large earthquakes.

Understanding the mechanisms behind these “tightly coupled” and “loosely coupled” zones along the length of the subduction fault is important for New Zealand and the rest of the world.

The co-leader of the operation, Phil Barnes of NIWA, said sophisticated instruments get valuable information from the boreholes drilled into the subduction zone.

Scientists will spend months analysing this information to better understand the conditions inside the fault zone, he said.

The JOIDES Resolution has been in New Zealand waters for 18 months conducting a series of expeditions, en route to Antarctica to find out how warming oceans will affect ice sheets, sea level and global weather systems.

A fresh group of 30 scientists from 11 countries boarded the ship over the past two days and set off from Lyttelton on Sunday for the Ross Sea, to spend nine weeks drilling holes in the sea floor to examine polar climatic conditions going back 20 million years.

When the JOIDES Resolution returns from the Ross Sea in early March, it will stop at Lyttelton again, pick up a fresh crew of scientists, then head back to the East Coast for a further probe of the Hikurangi subduction zone east of Gisborne.

It operates under the 23-nation International Ocean Discovery Programme (IODP), of which New Zealand is a member.

New Zealand takes part in the IODP through a consortium of research organisations in New Zealand and Australia, including GNS Science, NIWA, The University of Auckland, Victoria University of Wellington, and the University of Otago.