'Moderate' quake shakes Wellington

UPDATE - A 5.5 magnitude earthquake shook the Wellington region just before 8am today.

Geonet says the quake was centred 5km from Upper Hutt at 30km below ground.

Just minutes later at 8.02am a second quake measuring 3.7 on the Richter scale was recorded in the same location but 25km deep, GNS said.

This morning's quakes followed a flurry of seismic activity in the lower North Island on Tuesday when 10 earthquakes were recorded over a 10-hour period -- the biggest reaching 5.3 on the Richter scale and centred 40km southeast of Martinborough in the Wairarapa.

The police central communications centre in Wellington received a few 111 calls straight after this morning's quake.

"Most were from the Hutt Valley relating to alarms being set off, or people just wanting to know if it was an earthquake," a spokeswoman told NZPA.

Upper Hutt police said there were no immediate calls from the public, but the quake had been strongly felt in the concrete police station.

Newstalk ZB Wellington reporter Anne-Marie May says she heard a big rumbling noise.

"Then the whole building started to shake - it shook and shook and shook.

"There was some crashing out in the kitchen here, I think we've lost some of our crockery."

Lower Hutt chief fire officer Peter Bean told NZPA firefighters at his station had been thoroughly rocked by the quake.

"Video tapes were falling off the shelf and we got a few personal calls from our families at home," he said.

"It's certainly the biggest quake I've felt at the station."

However, the only callout by 9am was a sprinkler system activation in the suburb of Petone.

An engine from Rimutaka Fire Station had been sent to check a dam and water supplies in the area, Mr Bean said.

Kevin Fenaughty, data centre manager at the Institute of Geological and Nuclear Sciences (GNS), told NZPA there was no need to panic, despite the recent flurry of activity.

"It's certainly an unusual week in terms of the number we've had and the number which have been of this size which we've felt," he said.

"But to be fair, there's a reasonable scattering of locations of these things. There's been a number southeast of Martinborough, true, but this one in particular is around the Upper Hutt area," he said.

"It could be that there is a fair bit going on -- so some things are happening over in the east (of the region) which is causing stress over in the west. A bit like a chain reaction so there is a little bit of settling going on with the plates."

Mr Fenaughty said it was likely the quake was felt as far south as Kaikoura, on Marlborough's east coast, and Wanganui in the north.

"5.5 is certainly a moderate earthquake and because it's near a built up area it excites people more than if it was well away," he said.

The public had a heightened awareness of earthquakes at the moment, since the earthquake and subsequent tsunami that devastated parts of southern Asia on December 26.

"The word tsunami is flying around at the moment, but the reality is that earthquakes are always going to be the major risk in New Zealand, and we have to bear that in mind," he said.

GNS scientists were continuing to investigate this week's quakes and what they meant for the plates under the Wellington region.

- NZPA, HERALD STAFF