Aftershocks likely to stay deep

00:05, Jan 24 2014

The earthquake centred in Eketahuna on Monday is very unlikely to be followed by another large earthquake, but aftershocks will continue in the coming weeks, scientists say.

GeoNet spokeswoman Caroline Little said GeoNet received more than 9000 reports from members of the public who had felt the magnitude 6.2 earthquake, with multiple reports of damage.

Based on tectonics in the region, data from the Eketahuna quake, historical observations, and statistical models, scientists considered three scenarios that could occur in coming weeks, Little said.

Scientists predicted it was "very likely" aftershocks would continue to decrease in frequency, remaining deeper than 25 kilometres.

The second scenario - calculated as "very unlikely" - was that another earthquake with a similar size to the Eketahuna quake would strike.

"The earthquake could be at the same depth as the current aftershocks, in a nearby part of the Pacific plate.


"Or the quake could be centred at a shallower depth (i.e. less than 25 km) in the overlying Australian plate.

"If a shallower earthquake happens, there may be stronger shaking at the surface than the Eketahuna earthquake."

That scenario had a 9 per cent chance of happening within 30 days, according to the scientists' predictions.

Scientists predicted it was "extremely unlikely" that a quake greater than magnitude 7 would strike within 30 days.

However, as with many places in New Zealand, an earthquake of this size could occur at any time, Little said.

The Eketahuna earthquake had temporarily increased the chances of a larger magnitude quake striking - but scientists said there was less than a 1 per cent chance of one striking within 30 days.