Scientists have been researching earthquakes and tsunamis off the coast of Hawke's Bay as part of a national project.

Scientists from New Zealand, United States of America and Japan have spent the last week gathering data from the seafloor off the coast of Mahia and Gisborne to learn more about the Hikurangi plate boundary.

The team of 20 from GNS, Niwa, Victoria University of Wellington and overseas are spending two weeks aboard Niwa's research vessel Tangaroa collecting information to better understand how the Hikurangi plate boundary is moving and evidence of past earthquakes off the east coast of the North Island.

The ship is now moving south past Hawke's Bay to Wellington, and possibly Kaikoura, collecting sediment cores from the seafloor to be analysed.

Advertisement

A key aim of the research is to find out whether the plate boundary is capable of producing earthquakes higher than magnitude eight or nine.

GNS Science geodetic scientist, Dr Laura Wallace, who is leading the voyage, said a preliminary look at the data from the first part of their journey had shown clear signals from the Kaikoura and Te Araroa earthquakes last year as well as evidence of a tsunami and a slow-slip event off the coast of Gisborne.

"These were some of the things we were hoping to see," she said.

"This should help us to better understand the behaviour of the Hikurangi plate boundary, which is New Zealand's largest and most active plate boundary fault."

The information came from data from five seafloor pressure instruments that were retrieved off the coast of Hawke's Bay and Gisborne last week.

"It's going really well, we've had amazing weather for basically the whole time which helps with information gathering," Dr Wallace said.

The collection of seafloor pressure instruments and the deployment of nine more was completed ahead of schedule so core collection work started early Saturday morning to get a record of landslide deposits from earthquakes.

The pressure instruments record information continuously on the seafloor and the new nine will be collected next year and further instruments deployed to replace them.

They are capable of sensing vertical movements of the seafloor as small as 1cm and also track the passage of tsunami waves.

Seafloor movement is most obvious during earthquakes or periods of small tremor known as slow-slip events.

During the next phase, sediment core collection, scientists have been looking for geological evidence of landslides caused by earthquakes to try to reconstruct where and when earthquakes have occurred along the Hikurangi plate boundary.

"We are looking for specific sediment layers that are triggered by ground shaking, transported down-slope and eventually settle on the seafloor," Dr Wallace said.

Kate Boersen from East Coast LAB (Life at the Boundary) has been on board the ship sharing the progress with the public via a blog at www.eastcoastlab.org.nz.

"I'm looking forward to being able to share this research with everyone along the East Coast and Hawke's Bay so we can all benefit from the knowledge gained," she said.

"This information can add to our knowledge of earthquakes and tsunami risks along this coast, something we all need to understand better so we can be prepared."

The Tangaroa departed Wellington a week ago and will return early on Wednesday morning.

The research is part of a five-year Ministry of Business, Innovation and Employment research programme called "Diagnosing peril posed by the Hikurangi subduction zone: New Zealand's largest plate boundary fault".

The Hikurangi plate boundary is where the Pacific tectonic plate subducts underneath the Australian plate and is known as a subduction zone.

Subduction zones are responsible for the largest and most powerful earthquakes and tsunamis in the world such as the magnitude 9 earthquake offshore Japan in 2011.

USA and Japanese scientists have been on the voyage undertaking their own research to better understand subduction zones.