East Cape could be hit by an even bigger quake: Geonet

The area around East Cape the aftershock forecast covers. Photo / Supplied

Scientists can't rule out the possibility of a strong quake greater than magnitude 8 hitting the East Coast in the coming month.

Seismologists are predicting three different scenarios over the next 30 days based on the level of tremor activity since Friday's magnitude 7.1 quake that struck off around 100km off East Cape.

The worst case is the recent earthquake triggering a significantly larger quake at the point where the Pacific and Australian plates meet.

"This scenario is very complex and when combined with the current uncertainty in our models, we can't confidently put a probability estimate on it occurring," said Geonet.

Despite the large "triggered" tremor being "very unlikely", scientists could not discount the possibility of it happening.

This scenario was similar the devastating 2011 Tohoku Earthquake in Japan.

"Although it is still very unlikely, the chances of this occurring have increased slightly since the M7.1 earthquake," said Geonet.

However, scientists believed the most likely scenario was aftershocks would continue to be felt in the East Cape area and decrease in frequency.

This would follow the pattern of a similar magnitude 7.1 earthquake which occurred on Waitangi Day just to the south-east of Friday's quake. Aftershocks continued for more than two years.

As well there was a 50 per cent chance of a strong tremor of up to magnitude 6.9 striking the region within the next 30 days.

A more unlikely scenario was a second large quake of matching magnitude striking close to the original quake's epicentre.

"This earthquake may be onshore or offshore but close enough to cause severe shaking on land. "

If such an earthquake happened either north or south of the main shock area there was also the potential of a tsunami.

Geonet said while there were very different probabilities for each scenario some were more concerning than others.

"We recognise that while these scenarios may increase anxiety in people living in the area of the north east corner of New Zealand, the best thing is to be prepared. "