Power cut to thousands, discoloration in the city water supply and two buildings closed for safety reasons - this is the worst of the damage in Whanganui after a powerful earthquake in the South Island on Monday night.

The magnitude 7.5 quake was centred 15km north-east of Culverden in North Canterbury at a depth of 15km. It hit at two minutes past midnight on Monday.

Whanganui Mayor Hamish McDouall said there had been no reports of major damage in the Whanganui district.

Mr McDouall said Whanganui District Council's infrastructure staff had been monitoring water and sewerage systems.


The council Emergency Operations Centre was set up immediately following the earthquake, but had not been activated.

"[It's] unlikely to unless things dramatically worsen," Mr McDouall said in a Facebook post.

And for the first time staff were using its recently installed radio link through radio station Brian FM to broadcast updates as information came to hand.

Kym Fell, Whanganui District Council chief executive officer, said he and senior managers were onsite by 12.20am until 4am while two Civil Defence emergency managers remained in the centre after that.

"There was no confirmed damage of any significance," Mr Fell said.

He said the city's main bridges in the city were inspected in the early hours "and all have stood up to the quake".

The Bastia Hill Tower shed a considerable amount of concrete during the earthquake. Blocks of concrete up to 30cm across were strewn across the road below the tower; some were embedded in the grass.

A Bastia Ave resident, who did not wish to be named, said the tower made a lot of noise during the quake.

"It was making loud cracking noises, like rifle shots."

The man said he had lived in the house for 14 years and had never experienced a quake like it.

"I'm not too worried about the tower. They always say it was over-engineered, but it is getting old. What I was worried about was seeing a group of people in their dressing-gowns standing under the tower about 20 minutes after the earthquake."

The tower was cordoned off early yesterday afternoon, as was the Whiskas Grandstand at Cooks Gardens, until a structural engineer can do an inspection.

At least two water mains - one in Brassey Rd and one in Devon Rd - burst shortly after the earthquake, affecting Whanganui's water supply.

A council spokesman said while the water was still safe to drink, and was being chlorinated, it would be a dirty brown colour for some time. It may take a while to settle.

A spokeswoman for Whanganui Fire Service said it had had no earthquake-related call-outs.

Splash Centre manager Dave Campbell said water from two or three pools was sloshed out and went through the first aid room and reception area. Staff cleaned it up when they arrived for work.

He said Whanganui East Pool is empty, and any damage to it will not show up until it is filled in the next week or two.

Around 8,000 Whanganui properties were without power for anywhere up to five hours after the quake.

Powerco network coordination manager Dean Stevenson said the earthquake had caused overhead power lines to clash, triggering supply to automatically shut off. This was also the cause of the flashing lights and explosion-type sounds that people heard straight after the earthquake.

Mr Stevenson said each affected line must be physically checked by Powerco's field staff before power can be turned on again.

"They have done an amazing job at getting the power back on quickly and safely," Mr Stevenson said.

There have been reports of a small number of lines coming down across the network. People must stay well clear of fallen lines. If you see any, call Powerco's emergency number on 0800 272 727.

Damage in Rangitikei and Ruapehu districts was pretty minor, spokespeople said.

Although a strong earthquake was recorded 20km east of Ohakune at 1.35pm on Monday, locals reported that there appeared to be no damage.

Ohakune New World owner Dan Rolls said there was a big clean up job when staff arrived at work in the morning but there was no further damage from the afternoon shake, which measured 4.7.

"The shelves are all reinforced but there was a lot of product loss and the olive oil is not the easiest to clean up.

"Nothing fell off the shelves this afternoon because that shake didn't last very long," said Mr Rolls.

Ruapehu College principal secretary, Anne McIver, said she had not noticed the Monday afternoon earthquake.

"It could just be where my office is situated but I didn't feel a thing," she said.

Mrs McIver said the NCEA Level 1 science exam went ahead earlier in the day.

The Bulls water tower has been checked and is sound. One Ruapehu house was damaged by an unsecured water tank.

In South Taranaki, many residents were without power for some time. Slips were reported on Glen Nui Rd, east of Eltham. The road is still open but motorists should drive with care.

There was also a slip reported on Okahutiria Rd, north of Waverley. The road was closed but has since been re-opened.

Anyone with earthquake damage to their property is advised to visit the EQC website www.eqc.govt.nz and fill out their online form to obtain an EQC number which they can then supply to their private insurance provider, Horizons Regional Council emergency operations controller Craig Grant said.

People without internet access can call 0800 DAMAGE (326 243).

+Magnitude 7.5 earthquake hits North Canterbury at 12.02am on November 14, 15km north-east of Culverden at a depth of 15km.
+Two people are confirmed dead: one at Kaikoura and one at Mt Lydon.
+The earthquake is strong enough to cause clashing power lines in the North Island, including in Whanganui, leaving 8000 properties without power for up to five hours.
+Whanganui District Council's Emergency Operations Centre is set up but is not activated.
+Bastia Hill Tower and the Whiskas Stand at Cooks Gardens are cordoned off until a full assessment can be made of their safety.
+Two water mains in Whanganui burst shortly after the earthquake. Whanganui's water is still safe to drink, but it has turned a dirty brown colour.