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Focus on NZ tectonics at international science workshop

One hundred and sixty scientists from 10 countries will be in Wellington this week to draw up a wish list of research projects to investigate the mechanisms occurring at New Zealand’s offshore plate boundaries.

The aim of the three-day workshop is to prioritise a number of earth science research projects over the next decade, and to coordinate activities between New Zealand-based and international scientists.

Beneath the North Island the Pacific Plate is being pulled under the Australian Plate at a rate of about 40mm a year in a process called ‘subduction’. This gives rise to earthquakes, volcanism and other geological phenomena. In contrast, subduction of the Australian Plate occurs beneath Fiordland in the South Island.

Probing silent earthquakes

These subduction zones are among the more active in the world, and are thought to be capable of producing great megathrust earthquakes and tsunamis, yet little is known about the mechanisms at play at depth. The process of subduction is also responsible for the long history of volcanic activity in the central North Island and the Kermadec Arc.

Workshop participants will formulate a range of geological and geophysical initiatives to improve the knowledge of the subduction plate boundaries and their implications for geological hazards in New Zealand.

Among the initiatives discussed will be proposals to undertake scientific drilling into the interface between the Pacific and Australian plates east of Gisborne to obtain direct evidence of the processes occurring at the plate boundary. This project would involve inserting instruments in the drill holes to record a range of physical and chemical phenomena.

Other candidate locations for scientific drilling to understand subduction in New Zealand are in the Kermadec Arc, 400km northeast of the Bay of Plenty to assess processes involved in the formation of submarine volcanoes, and at the Lord Howe Rise about 1500km northwest of Northland to help understand how and why subduction began offshore northern New Zealand 45 million years ago.

“New Zealand is unique in the world in having a plate boundary that exhibits many different aspects of subduction, including a wide variety of earthquake and volcanic behaviour,” said one of the workshop convenors, Laura Wallace of the University of Texas.

“The New Zealand setting represents a superb opportunity for the international Earth science community to find answers to the many outstanding questions about why subduction zones behave the way they do,” Dr Wallace said.

“We are particularly interested in understanding the links between geological processes at the surface and what is happening at the plate boundary several to many tens of kilometres below the surface.”

Dr Wallace said the high level of interest in the workshop from overseas scientists reflected the importance of New Zealand’s geological setting in a global sense.

As part of its earth science research programme, the National Science Foundation in the US has picked New Zealand as one of three places in the world where a large amount of research effort and money will be spent on understanding subduction plate boundary phenomena over the next decade.

The NSF chose New Zealand largely because of the very high level of tectonic research that has already been done here by New Zealand-based scientists, and the outstanding opportunities for establishing productive collaborations between US and New Zealand scientists.

The New Zealand government’s substantial investment in scientific infrastructure, such as the GeoNet monitoring network, also makes New Zealand a compelling location for subduction zone research.

The other two NSF subduction zone focus sites are Cascadia, on the west coast of the US and Canada, and the Alaska-Aleutians area. The three areas are each hosting workshops to set their research agendas for the coming years.

Sponsorship for the Wellington workshop, being held at Te Papa, comes from the Ministry of Business Innovation and Employment, NSF, the Earthquake Commission, and GNS Science.

Probing a submarine volcano