6.4 quake and cluster of aftershocks in New Zealand

6.4 earthquake in South Island centered on Arthurs Pass.

Quake spate shakes South Island: Warning of 'sizeable' aftershock

A severe earthquake and a cluster of aftershocks have struck the central South Island today but the isolated location has prevented any damage or injuries.

This GNS map shows the location of the 6.4 magnitude quake in red, with some of the first 'felt reports' it received from around the region. Photo / GNS Science

NZ Herald,

6 January, 2015

The strongest tremor hit at 6.48am and measured 6.4 in magnitude.

It was centred 35km north of Methven and was 10km deep.

That was swiftly followed by more than 20 aftershocks - the largest measuring 4.2 in magnitude, which hit at 6.59am, 30km south west of Arthur's Pass, GNS said.

Twelve aftershocks were stronger than magnitude 3.

More than 2500 people have reported feeling the quakes, from as far south as Mandeville in Southland to as far north as Paeroa in northern Waikato.

Emergency services have reported no damage from the tremors.

A St John spokesman said there were no injuries to staff and no damage to the organisation's premises in Ashburton, Methven, Mayfield, Darfield, and Arthur's Pass.

Seismologist: 'Be aware there could be a sizeable aftershock coming'

GNS seismologist John Ristau said the initial quake was similar in size and depth as the devastating Christchurch earthquake that hit in February 2011, but its location had reduced the risk of damage.

"It's a fairly isolated area and it's not unusual to have earthquakes of this size.

"We've had them in the past century, there have been at least a couple of others that have been above magnitude 6."

It was not yet known which fault line caused the quake, Dr Ristau said.

"All of New Zealand is riddled with faults."

Aftershocks would go on for a while yet, which could reach the magnitude 5 range, he said.

"Just be aware there could be a sizeable aftershock coming - but beyond that we can't say for certain whether there'll be anything bigger coming."

'It was like the house was at sea'

New Zealand Herald readers have been sending in their experiences of the earthquakes.

Tony Foote said the quakes were "disturbing".

"It rolled on a bit, quite heavily and I felt a bit sea sick as my chair moved about. A bit like being on a rising and falling wave in a small boat.

"There was a worry it might be something bigger on the way as an ornament I hung to see when quakes were happening swung 100mm side to side for several minutes, and the water in my cat's bowl moved up and down 20mm or so."

Graham Walker said he felt the quakes in Timaru.

"As I was eating breakfast house was rolling around for about 10-15 seconds."

Others took to social media to describe the quakes.

Brian Feary tweeted: "Big earthquake here in Arthur's pass! My dog ran in from outside and jumped on bed... No damage so far #eqnz".

A user called The Queen of Cobden wrote: "That #eqnz just felt like the house was at sea (in Christchurch)".