'Good shake' wakes Northland residents

A magnitude 4.2 earthquake struck east of Whangārei last night, waking residents. Photo / File

A "good shake" that woke Northlanders up last night came two days after another earthquake shook buildings on New Year's Day.

GeoNet reported a 4.2 magnitude earthquake struck 12km deep at 1.38am 55km east of Whangārei.

One Tree Point resident Russell Foster had been fast asleep after staying up to watch the tennis on television when he woke to his house shaking.

"The whole house was shaking backwards and forwards. We had stuff falling off shelves even," he said.

"It was a good shake, that's for sure."

Foster, 80, said he and his wife both woke up and got out of bed immediately and went outside to listen for a tsunami siren.

"We often don't hear them where I am, so I was on my phone trying to find out what was going on."

He said he sent text messages to his family all around New Zealand, but didn't hear anything back so went back to bed.

Eighty-two people reported to GeoNet they felt the earthquake last night, with the majority of reports being of weak or light shaking.

A number of people on the Tutukaka Coast noticed the earth move on New Year's day.

A 4.2 magnitude earthquake was recorded 60km east of Whangārei at a depth of just 5km on Tuesday.

Kelly Stone, home from the shaky capital city of Wellington to visit her parents on the Tutukaka coast, said the quake had her on her feet and considering leaving the house.

Having lived in Wellington for nearly 10 years she was very familiar with quakes.

"This one would have made everyone in the office in Wellington get to their feet and consider their next move," Stone said.

"The whole house was shaking and the television was wobbling. It was comparable to those we get in Wellington and it was strong enough to have me thinking about getting outside."

Northland is the least seismically active area in New Zealand, along with south east Otago, seismologist John Ristau said.

To put it into perspective, last year there more than 19,500 seismic events recorded in New Zealand, only 32 of those in Auckland and Northland.

No place in New Zealand can escape the effect of the Australia and Pacific plates grinding together, which is the cause of the offshore nips deep under the seabed. Northland is near the boundary of the Pacific plate.

''Most of the earthquakes in New Zealand will occur close to these two main plates. Even though they're fairly rare in Northland, being part of New Zealand just means they're going to happen,'' Ristau said.

''Earthquakes like this [Whangarei cluster] are a good reminder to people that even in Northland we are never far from seismic activity.''

Regarding a possible tsunami, Ristau said the recent Northland events were too far east, too deep and too small to even cause a ripple in the ocean.

As for why hundreds of people feel the earth move in a shake which are categorised as Unnoticeable, it's because of the way the algorithms used in the recorded data are set.