The National Emergency Management Agency (Nema) has issued an update this evening saying the areas that were earlier under the National Advisory experiencing strong and unusual currents have reduced further. 

Due to rebounding tsunami activity from South America, the east coast of the North and South Islands and the Chatham Islands remain under a National Advisory and are likely to remain so overnight, the agency said in the update. 

The remainder of the West Coast of the South Island and Cook Strait that remain under a beach and marine tsunami threat are assessed as only just reaching the threshold for such a threat. 

The next update is expected around 8am tomorrow.

As the tsunami threat loomed at dawn, Auckland Council contractors were spotted getting to work.

In their high-vis jackets, the workers started mowing the lawn in St Heliers soon after an emergency alert jolted New Zealanders awake this morning.

Civil Defence director John Price blasted these workers for their complacency, saying they could have put first responders at risk by continuing to work; despite what he said, they were in fact entitled to work there.

Read more below.

People can expect State Highway 3, Ōtorohanga near Kakamutu Road to remain closed overnight in both directions due to a slip, according to NZ Transport Agency Waka Kotahi (NZTA).

Further rain forecast this evening means crews will be unable to repair the road tonight.

NZTA is advising motorists to delay their journey or allow extra time for a detour via Huiputea Drive.

The National Emergency Management Agency (Nema) has issued an update this afternoon saying the areas under the National Advisory experiencing strong and unusual currents have reduced.

Due to rebounding tsunami activity from South America, the east coast of both the North and South Islands and the Chatham Islands remain under a National Advisory, and are likely to remain so overnight.

The west coast of the South Island, and Cook Strait, meet the threshold for the National Advisory to remain in place. However, the tsunami activity threat is at the low end of the scale.

Strong and unusual currents on the eastern side of New Zealand may be present for another 24 hours.

Strong currents and surges can injure and drown people. There is a danger to swimmers, surfers, people fishing, and anyone in or near the water close to shore.

The next update is expected around 7.30pm.

New Zealand tsunami gauge network data has revealed the peak tsunami waves recorded across New Zealand.

The largest tsunami wave to hit New Zealand shores was 51cm high on the Chatham Islands, GeoNet said. 

A summary of Geonet's tsunami gauge reading:

• The first NZ arrival was detected about 1am on the North Cape tide gauge.
• Arrivals proceeded down the country over the course of the next 90 minutes or so.
• The largest-amplitude arrival so far was seen on the Chatham Islands, 51cm, at 6:17am this morning.
• The largest mainland arrival was 31cm at Gisborne at 8:20am.
• The smallest arrival is difficult to pick as many are about the same height. Broadly, we have seen tsunami of 10cm in amplitude and above at all our gauges.

"I don't have the luxury of complacency at all as minister, neither does Nema," Emergency Management Minister Mark Mitchell told media.

"I don't have the luxury of operating on an optimism bias. That is how people die," he said.

"I apologise that people have been woken up through the alert, but I make no apology for the fact that we're taking the responsibility seriously."

"We know that we're still seeing tsunami activity, that's still occurring. So, you know, the warning remains in place," Mitchell said.

Emergency Management Minister Mark Mitchelljustified the emergency alerts telling media: “I can tell you right now that if we hadn't done that and there'd been half a dozen people swept off the beach this morning when they were walking their dogs at 6:30 and had been drowned, then I'd be standing here being asked why we didn't use our national alert system".

Emergency Management Minister Mark Mitchell is currently speaking to the media about the tsunami threat following the massive earthquake.

Defending the decision to send out mobile phone emergency alerts, Mitchell said: “We don’t have the luxury of playing russian roulette with people’s lives.”