Strong quake rattles central North Island

Some people described the shaking as 'huge'. Photo / Thinkstock

North Islanders were again rattled by a strong earthquake yesterday, but experts say the tremor was not related to a much larger quake four days earlier.

GeoNet reported a magnitude 5.7 quake struck 10km south of Turangi at 12.50pm. The quake was 90km deep and, though police said there were no reports of damage, some residents said trinkets had been smashed.

It came four days after a magnitude 7 earthquake, centred at a depth of 230km and offshore from Taranaki, rattled residents from the Bay of Plenty to Canterbury, but caused little damage.

Shaken people took to social media and message boards yesterday to share their experiences, some describing the shake as "huge".

A Trade Me post from Taumarunui said the quake "smashed a few photo frames" and GeoNet duty seismologist Lara Bland said a report on their website from a Turangi resident indicated some damage.

However, central North Island residents spoken to by the Herald on Sunday were stoic. Raetihi woman Wiki Brown said she felt a little tremor and "that was it".

"The 7.0 was out of it. The whole house was shaking, I thought the mountain was blowing up. This quake was tiny."

Another Raetihi resident, Creedence McNaught, described the quake as "just a little shake".

Several residents spoken to in Turangi said they did not feel the quake.

Pura Smith was alerted to the drama by a friend who felt the earthquake 100km away in Napier.

"I never felt a thing. Turangi's still standing."

Bland said she was not surprised the quake felt stronger to those further away from the epicentre.

That was because the tectonic plate was dipping under the North Island, so energy from it travelled back up the plate following the easiest path available, which was to the east.

"On our maps [of earthquakes felt], there is a big empty space around Turangi. Sometimes it actually feels weaker to those closer to it."

Even though the two quakes this week occurred on the same plate, that was the only similarity. "The distances are too great for one to have affected the strains of the other."

Neither had caused major damage because of their depth.

"That's the problem in Christchurch - it has the misfortune that its earthquakes have been very shallow, so almost all the energy comes up to the surface."

The Canterbury earthquake sequence began with a magnitude 7.1 tremor, centred 10km deep and 40km west of Christchurch, but it was a 5km deep, 6.3 magnitude aftershock that struck 5km from the city months later that caused the bulk of the damage and the mass casualties.

Yesterday's quake did not mean future shakes were any more or less likely than before, Bland said.

"It's just another day, another earthquake. It's just New Zealand."