A new video from GNS shows how last week's earthquake rippled throughout the country causing severe ground movement.

The complexity of the Kaikoura Earthquake and the number of faults that ruptured could be a clue to what has so far been a relatively low number of aftershocks.

GeoNet says the number of aftershocks are within the forecast range - but on the low side.

Work was continuing to try to understand the aftershock sequence following the Kaikoura quake, GNS Science seismologist Matt Gerstenberger said.

DAVID WALKER/FAIRFAX NZ A shallow M5.7 aftershock eight days after the Kaikoura earthquake caused major damage to the Scargill area of North Canterbury, but it was part of an aftershock sequence at the lower end of forecasts.

"We're doing lots of modelling now to understand what the faults were that ruptured. We're getting much better models now."

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That data would help improve understanding of the aftershock sequence.

GNS SCIENCE/YouTube Drone video of the Kekerengu Fault rupture

"It (the Kaikoura quake) started to the south, then it jumped across a whole series of faults, some of which were connected up and some of which weren't necessarily connected up," Gerstenberger said.

"We're learning a lot more from this one (the Kaikoura Earthquake), and seeing how complex and how many different faults were involved in this rupture."

"It could be all of that is contributing to the low number of aftershocks but we don't know that for sure, but that is one possibility."

KATE PEDLEY/UNIVERSITY OF CANTER Images of the scarp created near Waiau by the Kaikoura earthquake.

Following the massive magnitude-7.8 quake just after midnight on November 14, GeoNet recorded two aftershocks of M6.0-6.9 between 15 minutes after midnight and noon, as well as 24 aftershocks from M5.0-5.9.

In the next 24 hours there was 1 aftershock from M6.0-6.9 and 12 from M5.0-5.9.

After that the number of large aftershocks fell away rapidly but remained within the forecast range. That's not too surprising given that the low end of the range for M6.0-6.9 aftershocks was zero from the start, while for M5.0-5.9 aftershocks it was zero after four days or so.

As the magnitude of an earthquake increased, so the number of aftershocks expected generally increased, Gerstenberger said.

"But for a given magnitude you still expect a wide range in the possible numbers of aftershocks you might get."

The aftershock models were based on the historical behaviour of aftershock sequences around New Zealand, adapted "a little bit" to each sequence as it developed.

And just because aftershocks were at the low end of the forecast so far, it did not mean they would stay there.

"We could have another big aftershock."

By 7am on Thursday, GeoNet had recorded 6779 aftershocks since the Kaikoura Earthquake, of which 197 were in the previous 24 hours, including one over M4.

Gerstenberger said the proportion of larger aftershocks among the total was consistent with what was expected from aftershock sequences in New Zealand. "They're both on the low side of average."