"This slow-slip event is particularly interesting as it appears to involve slip along the plate boundary from Hawke's Bay up to East Cape at the same time," Dr Wallace said.
Normally slow-slip events are separated in time or happen one after the other.
"It is possible that passing seismic waves from the M7.8 earthquake caused stress changes that triggered the slow-slip event," she said.
Slow-slip events were discovered in North America a few decades ago and only picked up in New Zealand when GPS stations were installed around the North Island in the 2000s.
"The precise linkage between slow-slip events and standard earthquakes is not well understood - this is still an area of active research," Dr Wallace said.
Meanwhile, GeoNet drone footage has shown the more dramatic surface impact of the of the Kekerengu Fault, one of several faults that ruptured during the Kaikoura shake.
The surface rupture, which moved 10m horizontally and 2m vertically, runs 30km through rolling farmland in southern Marlborough.