But quakes that struck at the depth Tuesday's did still sent their seismic waves propagating to shallower parts of the great slab – which meant the quake would have been felt more strongly in Hawke's Bay and Wellington.
Townend described the Pacific plate slab as a "funnel" that sent seismic waves across a wider area when a quake happened.
"The Pacific slab is old, cold and rigid, and transmits seismic waves very efficiently."
He said the quake would have either resulted from the two plates rubbing together – or the Pacific plate contorting, which was the likelier scenario.
The earthquake's physical orientation - or "focal mechanism" - suggested to Townend that it was reflecting stresses within the Pacific plate induced by a combination of flexure and thermal stresses.
"The cold Pacific slab is heating up as it goes deeper and deeper into the mantle."
The jolt's aftershock potential wasn't immediately clear – but large, deep quakes like today's usually caused fewer aftershocks than shallower ones.
New Zealand's geology could also explain why people in Auckland wouldn't have felt the quake.
The seismic waves it generated would have lost their energy as they propagated northward and hit hot mantle rock deep beneath the North Island.
"It would be like walking through hot toffee – it just soaks up all the energy."
This was also the reason the quake wasn't as felt as strongly even in Taumarunui – as the waves had to propagate directly upward, through the hot mantle.
The waves would have also been slowed by crustal rock near the North Island's surface – and then further absorbed by Auckland's volcanic geology.
"But if you were south-east of the quake, and near the plate boundary, it would have been coming at you quite strongly."
Such strong deep quakes happened "intermittently" in New Zealand – although countless more would occur at that depth that were too small to be felt.
GeoNet compared the quake to a another 6.2 event that struck south of Taranaki, at a depth of 241km, on July 3, 2012.
Wellingtonians reported it lasted for around 30 seconds to a minute, many thankful the quake was more of a gentle roll than a frantic shake.
Wellington-based Herald reporter Lucy Bennett said the shaking was quite gentle.
"There was a gentle shake and a jolt. It kept rolling on and then there was another jolt," Bennett said.
She went outside following the shaking to see if there was any damage and said "life was continuing as normal".
Tejinder Chawla wrote: "I felt the earthquake in Wellington Wills Street. Felt it 1st time and was little shaky ... as almost dropped my coffee on me."
Kasey MacKinnon, who moved to Wellington from Christchurch recently, said the quake was the biggest one she had felt in a long time.
"Biggest one I've felt in a long time and first one since moving to Wellington two months ago."
International media was quick to react to the Royal couple "surviving" the shake which was felt throughout our nation.
Prince Harry and Meghan were preparing to meet-and-greet Auckland locals at the Viaduct Harbour when the earthquake struck.
The Express said there were no reports of the Duke or Duchess of Sussex being impacted by the earthquake.
Elsewhere, The Sun reported more than 9000 people had reported feeling the earthquake within 10 minutes of it striking.
Parliament was suspended temporarily this afternoon due to the quake, Deputy Speaker Anne Tolley stepping up and making the decision.
The sitting of Parliament was suspended to allow time for a check of the buildings and staff. It was resumed about 3.40pm.
The gentle but prolonged shaking meant much of the nation was spared from any damage, Civil Defence Minister Kris Faafoi said.
He said the Ministry of Civil Defence got in touch with the Manawatu/Wanganui Civil Defence group and confirmed there had been no reports of any damage.
"We are still making sure we work through the process of contacting everyone to see if there is any."
But if there was anything major – "we would have probably heard about it by now."
He said Civil Defence would continue to check to makes sure there was no damage.
Faafoi said the quake was a "timely reminder of some of the basics in and around dropping, covering and holding."
He said it had "obviously given people a bit of a shake" and asked people to be vigilant.
"Make sure you're checking on your neighbours, friends and family."
He was not aware of any increased risk of volcanic activity as a result of the quake and thus far, there had been no reports of this being the case.
Victoria University's Professor John Townend suspected the earthquake was so widespread because the Pacific plate acted as a "funnel".
"The Pacific slab is old, cold and rigid, and transmits seismic waves very efficiently," he told the Herald.
The earthquake was felt as far down the country as Christchurch and as far north as Auckland, GeoNet reported.
A Christchurch Fire and Emergency spokesman said his whole office based in the CBD felt the quake.
"It was quite a significant shake but no damage or injuries have been reported yet."
Olivia Allison felt the quake in Palmerston North.
"Wholly [sic] crap we just had an epic quake in Palmy. First Big one since I've been back. Just keeps going," she said on Twitter.
A Christchurch man said the quake felt "yuck". He said he was six floors up in a concrete-clad Government building that began to sway.
Back in Wellington, the quake temporarily impacted flight plans, with several planes delayed to land and take off from the capital.
An Air New Zealand spokeswoman told the Herald a small number of flights were partially delayed from landing in Wellington following the incident.
GeoNet compared the quake to another 6.2 event that struck south of Taranaki, at a depth of 241km, on July 3, 2012.
Recent large quakes in NZ
• July 2017: North-west of Auckland Island, Magnitude 6.6, depth 10km
• November 2016: Kaikoura, Magnitude 7.8, depth 15km (two deaths)
• September 2016: East Cape, Magnitude 7.1, depth 55km
• February 2016: Christchurch, Magnitude 5.7, depth 15km
• April 2015: St Arnaud, Magnitude 6.2, depth 52km
