Strong currents and unpredictable surges can be expected in coastal areas around New Zealand after a 8.8 earthquake near Russia, the National Emergency Management Agency says.

All coastal areas around New Zealand are covered by the warning. The surges are expected to reach New Zealand about midnight.

NEMA says strong currents and surges can injure and drown people.

They're warning people in or near the sea to move out of the water, off beaches and away from harbours, marinas, rivers and estuaries

"People on boats, live-aboards and at marinas should leave their boats/vessels and move onto shore," NEMA said.

"Do not return to boats unless instructed by officials.There is no need to evacuate other areas unless directly advised by local civil defence authorities."

The threat of a tsunami was reassessed after the Russian earthquake was upgraded to a magnitude 8.7. It was later upgraded further. The quake struck off the eastern coast of Russia on Wednesday.

NEMA earlier said there was no threat to New Zealand, but the quake was later upgraded to a 8.7 – meaning the threat had to be checked again.

The west, east, and south coasts of the North Island, and west, east, south and top of the South Island were all affected, as were Stewart and Chatham Islands.

NEMA says flooding of land near the shore was not expected. But people in the water or near the shore were told to move.

People should not go to the coast to watch as unusual wave activity could be dangerous, it says.

The strong and unpredictable surges and currents will continue for several hours.

– NEMA

Parliament was momentarily disrupted when the tsunami alert sent to people's phones rang around the House.

The alert from NEMA was sent to phones at 4.12pm, warning people of strong and unusual currents, and unpredictable surges, following the magnitude 8.8 earthquake near Kamchatka, Russia.

Parliament was at the time debating a bill.

Assistant speaker Barbara Kuriger suspended the House for a few minutes, while it was determined what the alert was about.

The debate resumed a short time later.

Milford Cruising Club commodore Andrew Robertson said members had been messaging each other about the warnings.

"We have had a note go out to just be aware of the activity in the area," he said.

"The boaters themselves have been in contact with each other to raise awareness of the issue."

But Robertson said the marina, which nestled in the Wairau Creek, was relatively safe from tidal activity.

"I'm not really (worried).  Milford Marina is quite sheltered and we probably experience storm surges every time we have a strong north-easterly, like we had two days ago, but not worried at the moment unless the warnings were to escalate."

Bucklands Beach Yacht Club manager Lyle Tresadern shared a similar sentiment.

"There's a lot to get through to get to us. Over previous years we haven't had much of a problem with tidal warnings," he said.

A spokesperson for Waiheke Marina says it has notified boat owners of the risk and asked anyone currently at the marina to leave.

They say the marina will be closed from 6pm tonight and security will monitor the risk from higher ground.