If the whole region ruptured, the results would be potentially catastrophic.
‘We need to think Japan 2011 basically, because if our whole plate boundary ruptured it would be a magnitude-9 earthquake,' GNS scientist Ursula Cochran told the publication.
'One thing about reflecting on the Kaikōura earthquake is we don't want people to think this is the big one,' she continued.
A subduction zone is the name given to a region where one tectonic plate passes under another plate, causing something called a 'megathrust'.
The expert added that a tsunami caused by a resulting quake could potentially take just seven minutes to devastate the coast.
The news comes at a time when many New Zealanders may be feeling jittery – after the capital Wellington was rocked by a 4.1 magnitude earthquake on Sunday night.
The tremor, which struck at 2.31am, woke thousands from their sleep.