A flurry of strong earthquakes have rocked the North Island this morning, causing damage in Hawke’s Bay. Civil Defence has confirmed there is no tsunami threat.
The first quake, magnitude 5.9, hit at 10.16am and was centred at Pōrangahau in Hawke’s Bay, Geonet said the tremor was 24 km deep.
A second quake, magnitude 5.4, hit three minutes later in the same area at 17km deep. Both quakes have been regarded as severe.
At 10.21am a third quake hit in the same area measuring magnitude 3.9. The third tremor was at a shallower depth of 14 km and centred 10 km west of Pōrangahau.
A series of aftershocks have followed, with a total of 10 earthquakes hitting the region in 25 minutes.
New Zealand Civil Defence confirmed the quakes had not sparked a dangerous tidal wave across the eastern coastline.
‘It’s all damaged. Everything is on the ground’
One Pōrangahau resident said the area had been "smashed by the biggest earthquake".
"S*** flying everywhere out of cupboards and shelves, a second one just starting out house is rocking uncontrollably."
"We are getting in our car, too dangerous in the house the shakes are continuing," a Pōrangahau resident said on Facebook.
A staff member at the Duke Hotel in Pōrangahau was in the upstairs office when the whole building shook from side to side.
"It’s all damaged. Everything is on the ground.
"We are just on the phones at the moment trying to find out if we have to evacuate, questions about the tsunami are definitely rising."
Robert Houkamau, whose father owns the Duke Hotel in Pōrangahau, said it was a severe shake.
He said the initial quake lasted about 30 seconds followed by aftershocks lasting up to 90 seconds.
Staff were assessing the damage.
"The single bottles in the chiller have been thrown around. Bottles have been broken and some have fallen over."
He said the earthquake was a "little bit concerning" because of the township’s proximity to the coastline about 1.3km away and the possibility of a tsunami.
Felt by at least 50,000 people
The shakes have been felt widely across the lower North Island with people in Wellington reporting a rolling motion.
In Napier, office employees hid under desks as the quake rolled for roughly a minute.About 50,000 people throughout the country have recorded feeling the four earthquakes, according to GeoNet.
"I have never felt such huge shakes," a Porangahau local wrote online.
"I thought our old house was going to fall down, they are still going."
Geonet said there has been severe shaking in Porangahau this morning with a M5.7 tremor followed closely by a M5.3.
"Our team are still looking at this so the size/locations are currently preliminary. We will have updated information ASAP," it posted on Facebook.
A homeowner on the Kapiti Coast said he felt a "rolling, rocky roll" which lasted about 30 seconds.
"It wasn’t a big shake, just a rolling motion."
The man’s house is on the Raumati South beachfront, but he was not concerned about any potential tsunami and didn’t plan to move to higher ground.
"I don’t think any tsunami is going to reach us here because we’re 10m above the mean high tide level."
‘Some of the larger we’ve seen in the last 10 years or so’
GNS Science geophysicist Dr Laura Wallace said the quakes occurred in a region that “experiences seismicity relatively frequently”.
”In the past, we have frequently seen swarms of moderate to large earthquakes there, but the two events today were some of the larger ones we’ve seen in the last 10 years or so.”
The region sat near the boundary of the Pacific and Australian plates – where the former dived under the other, westward beneath the North Island, to create the Hikurangi Subduction Zone.
It also happened to be a hot spot for slow-motion earthquakes called “slow-slip events”, which could released pent-up energy over weeks, months and years. These tended to happen within areas where the subduction zone was transitioning from being “stuck” beneath the southern North Island, to an area where the subduction zone was “creeping” further north, around Gisborne and Hawke’s Bay.
One such event – linked to a 6.3 quake in Kapiti in February – was still going deep beneath the Manawatu and Horowhenua regions, and Wallace suspected today’s shakes were also connected to the process.
”Sometimes we can get earthquakes like this when we’re not having slow slip, but I’d think that there is a reasonably high likelihood that this could be related to the Manawatu slip event that’s ongoing,” she said.
”It’s not very far from that area and we do tend to see swarms of earthquakes like this during those Manawatu slow-slip events.”
