9 Oct 2016

Severe quake off East Cape an aftershock

2:34 pm on 9 October 2016

This morning's big earthquake off the coast off the East Cape coast is an aftershock of the 7.1 quake that hit a month ago, a GNS seismologist says.

The shallow, 5.8-magnitude earthquake struck about 75km out to sea off Te Araroa, at 8.41am. It was at a depth of 7km.

The quake was centred 75km out to sea. off Te Araroa.

The quake was centred 75km out to sea off Te Araroa Photo: GeoNet

The quake, rated 'severe' by GeoNet, was widely felt along the North Island's east coast and as far north as Kerikeri, with a scattering of reports in the South Island as well.

Two smaller tremors followed - of 3.1 and 2.8 - centred 20km and 15km from Te Araroa.

The area was hit by a 7.1-magnitude quake on 2 September, with dozens of aftershocks, sparking a tsunami warning, evacuations from coastal areas and school closures.

GNS seismologist Anna Kaiser said East Cape residents should be prepared for more aftershocks over the coming months.

"We've had some magnitude 6 aftershocks in the same day and following days after [the September] quake and now we're starting to see aftershock activity still ongoing and that's entirely expected," she said.

"This aftershock was offshore, right in that region, and it forms part of the typical kind of behaviour we might expect." Aftershocks would continue but become less and less frequent.

Tairawhiti civil defence manager Louise Bennett said said today's shake wasn't as severe as the September earthquake and area co-ordinators thought damage was unlikely, but were checking for any reports.

"It was ... 20 seconds, it was rolling, it wasn't a jolt," she said.

"And therefore they [area co-ordinators] felt that there wasn't the need to evacuate."