New Rutherford Discovery Fellow to investigate mega-thrust

11 November 2016
New Rutherford Discovery Fellow to investigate mega-thrust earthquakes

GNS Science seismologist Yoshihiro Kaneko has been awarded a prestigious Rutherford Discovery Fellowship to investigate the slip behavior on the tectonic plate boundary below the North Island’s east coast.

This is the first time a GNS Science researcher has won a Rutherford Fellowship, with Dr Kaneko being awarded $160,000-a-year for the next five years.

The project will see Dr Kaneko using state-of-the-art seismological techniques, numerical modelling, and analysis of earthquake recordings to shed light on the mechanism of complex slip bevahiour at subduction plate boundaries.

The focus is the Hikurangi subduction zone beneath the North Island’s east coast, which scientists believe is capable of producing mega-thrust earthquakes such as the magnitude 9.0 Tohoku quake and tsunami that struck Japan in 2011.

The findings will be applicable for understanding earthquakes at plate boundary subduction zones worldwide.

“I am delighted to be awarded this fellowship. It will allow me to develop a flow of work that will have international implications in seismology and it will lead to improved estimates of hazard impacts,” Dr Kaneko said.

An early part of the project will involve the deployment of portable seismometers in southern Hawke’s Bay for up to 18 months. They will provide very accurate recordings of even small earthquakes under the lower North Island.

Dr Kaneko will then do sophisticated analysis on the data on high performance computers at the New Zealand eScience Infrastructure, which provides support systems so New Zealand researchers can tackle some of the world’s biggest science challenges.

A novel feature of this part of the project will be wave-form analysis which Dr Kaneko says is a more elaborate approach to earthquake analysis. This is where the entire wave energy of an earthquake is used for analysis rather than certain parts of it.

The analysis will enable the building of a 3D model of the plate interface under the lower North Island to a depth of about 30km.
Dr Kaneko will then develop and test several hypotheses for the slip mechanisms on the subduction interface – the surface between the two plates where mega-thrust earthquakes initiate.

The project will also investigate the roles of frictionally weak rocks and fluids on the interface and how they influence slip behavior.

Part of the ethos of the Fellowships is to nurture the next generation of scientists and Dr Kaneko plans to recruit PhD and Masters students to help with the project.

Monitoring by GPS instruments over the past two decades has revealed that a large part of the Hikurangi interface under the lower North Island is currently locked. This implies that stress is building up for the next mega-thrust earthquake.

However, there is a large variation in the degree of locking over the length of the fault, with complex patterns of localised fault slip occurring continuously.

Scientists have observed similar patterns of slip behavior at many other Pacific rim subduction zones.

Dr Kaneko says the Hikurangi subduction zone offers a unique opportunity to this type of seismological investigation, largely because of its shallow depth below the seafloor and a long record of well-recorded earthquakes.

Ten Rutherford Fellowships are awarded to early to mid-career scientists each year. The awarding of a Fellowship typically has significant value in the future career of a researcher.

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