Scientists have uncovered hidden faults beneath the seafloor which explain the puzzle of slow earthquakes in the east coast of the North Island.
And an expert says the new discoveries could help to improve tsunami and earthquake warnings.
The study, conducted by a team of international scientists, revealed that a slow earthquake has been occurring in Hawke’s Bay since May this year.
The faults that these slow slip events occur on have a trait that allows them to release the stress from two plates colliding over a long period of time, rather than the seconds a normal earthquake takes to release the stress.
Dr Philip Barnes, a principal scientist from Earth Sciences New Zealand who was involved in the study, said the slow slip events themselves are not earthquake or tsunami risks. But in regions where the events occur, earthquakes can be triggered.
“Understanding what controls them is vital to improving earthquake and tsunami warnings.”
The hidden faults where slow slip events occur run along the Hikurangi Subduction Zone, particularly around the northeast of the North Island, Hawkes Bay and Poverty Bay.
Dr Barnes said Canterbury could also potentially be impacted by the fault.
This newly discovered fault runs down to north-east Marlborough, meaning that if a large slow slip quake were to occur, tsunami waves would be seen on the Canterbury Coast and coastal residents may feel the ground shaking.
However these effects would not be the same as other significant Christchurch earthquakes.
“It's quite a different fault to those that broke in the Canterbury earthquakes of 2010 and 2011. Those faults were local to Christchurch City and they were what we call crustal earthquakes."
Dr Barnes said the new findings were only part of the research project.
“We're putting lots of effort into a bigger understanding of how the fault is working. Our recent research is just part of quite a lot of ongoing studies.”
