Researchers In Search Of Earthquakes Off Wairarapa Coast

An international team of scientists is setting sail this Saturday on the NIWA Research Vessel Tangaroa to get a better understanding of earthquake and tsunami risk from our largest and most active fault, the Hikurangi Subduction Zone.

Thanks to funding from Toka Tū Ake EQC, the Canadian Foundation for Innovation, the University of Ottawa and GNS Science vessel time allocated by the Tangaroa Reference Group, the scientists will deploy ocean bottom seismic sensors that will record data for about one year. This offshore network will be able to detect earthquakes that are either too small or too far offshore to be recorded by the GeoNet network onshore.

“We’re effectively blind to small earthquakes occurring offshore,” says team leader and Te Herenga Waka-Victoria University of Wellington Professor, Martha Savage, whose research is funded by a Biennial Grant from Toka Tū Ake EQC.

“Previous studies have investigated areas of the Hikurangi Subduction Zone where slow-slip events are occurring, relieving stress on the plate.” said Professor Savage “This is the first study to look for earthquakes on the locked part of the fault.”

Toka Tū Ake EQC Head of Research Natalie Balfour explains that each year the agency invests around $10 million into natural hazard research and this project could have significant benefits for New Zealanders living in central New Zealand.

“If we better understand the locked portion of the fault and the smaller earthquakes that occur, it will help us prepare for the impacts of a large earthquake and potential tsunami should the fault come unstuck,” says Dr Balfour.

The Hikurangi Subduction Zone is a plate boundary fault, where the Pacific tectonic plate dives down westward beneath the Australian tectonic plate. It runs the length of the east coast of Te Ika-a-Māui/ North Island.

In places, the two tectonic plates are slowly sliding past each other, regularly releasing some of the accumulated pressure, but in other places they are locked together, stuck and building up pressure which could be released as a major earthquake.

“We’re expecting to see 10 times more earthquakes on the locked zone than are currently reported,” says Professor Savage.

“The behaviour of these more frequent small earthquakes can tell us more about the larger earthquakes that occur less often.”

On Saturday, the cruise led by GNS Science alongside scientists from Te Herenga Waka-Victoria University of Wellington and the University of Ottawa and Dalhousie University in Canada, will set off from Wellington to deploy the brand new ocean-bottom sensors off the coast of Wairarapa.

“In addition to identifying small earthquakes, the network will also record larger earthquakes from New Zealand and overseas that can help us to map and understand the geometry of the subduction zone”, explains University of Ottawa Professor Pascal Audet.

“Information carried by these seismic waves can also help us to better understand the likelihood of earthquakes, and how the movement of a future earthquake might cause a tsunami.”

The NIWA operated Research Vessel Tangaroa is supported by the NZ Ministry of Business Innovation and Employment (MBIE) Strategic Science Investment Fund.

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