New research has revealed the 2016 Kaikoura earthquake was an influencing factor in a series of small to moderate earthquakes in the North Island last year, after it triggered the "largest and most widespread episode of slow slip observed in New Zealand".
A slow slip event is a similar to an earthquake, but instead of taking seconds it takes weeks and months.
In a GeoNet blogpost, GNS Science explained their research, with Dr Laura Wallace saying slow slip events caused by the Kaikoura earthquake was "probably the clearest example worldwide of long distance, large-scale slow slip triggering".
"The magnitude 7.8 Kaikoura earthquake was one of the most complex earthquakes ever recorded with modern instruments," they wrote.
The slow slip was detected less than 15 kilometres below the seabed and over more than 15,000sq km along the Hawke's Bay and Gisborne regions, known as the Hikurangi subduction zone.
That particular slow slip was said to have been responsible for some small to moderate earthquakes off the east coast last year, the largest being a magnitude 6 offshore from Porangahau (located about halfway between Hastings and Castle Point) on November 22, 2016.
Dr Yoshihiro Kaneko said the slow slip "was triggered by stress changes in the Earth’s crust caused by passing seismic waves from the Kaikoura quake".
It showed the seismic energy from the Kaikoura earthquake travelled northwards, increased tension to the Hikurangi subduction zone, triggering the slow slip event.
A mass of sedimentary rock "piled up at the edge of the subduction zone" also contributed to the triggering of the large slow slip, the blog said.
The research is said to increase understanding about the relationship between earthquakes and slow slip events.