Four tremors of severe intensity measuring between 5.6 and 5.8 were felt in a 40-minute period on Monday night. There have been no reports of damage.
Three were located east or south-east of the Marlborough town of Seddon, while one was east of Kaikoura, which is already cut off to the north and the south.
They were among a host of aftershocks above 5, the highest so far being a 6.3 shake, since the initial earthquake struck just after midnight on Monday.
Dr Mark Quigley, from the University of Melbourne, says that, for an earthquake of magnitude 7.5 to 7.8, several large aftershocks (greater than 6) are expected.
"For each magnitude 6 aftershock, we expect 10 more magnitude 5 aftershocks over the coming days and weeks," he said.
Dr Quigley, who is Associate Professor in active tectonics and geomorphology at the university's School of Earth Sciences, said the region had been one of the most seismically active in the New Zealand over the past few years.
New Zealand Prime Minister John Key, centre, and acting Civil Defense Minister Gerry Brownlee, right, fly over Kaikoura, New Zealand, Monday, Nov. 14, 2016. (AAP) Source: AAP
PM John Key shocked by damage
Prime Minister John Key has made his first visit to earthquake ravaged Kaikoura just hours after New Zealand's third largest earthquake on record struck the coastal South Island town.
Mr Key was joined by acting Civil Defence Minister Gerry Brownlee and opposition leader Andrew Little on an Defence Force helicopter that toured the devastation on Monday afternoon.
The trio flew over Blenheim and Seddon, which has also damaged from the quake.
There are also reports of liquefaction at Blenheim, a phenomenon where soil and silt lose strength and stiffness and behave like a liquid.
Mr Key and Mr Brownlee were shocked by the amount of damage around Kaikoura, which is expected to cost hundreds of millions of dollars and take months to repair.
Earlier Mr Key said rebuilding confidence and assessing the damage were the first steps to recovery after New Zealand was rocked by a magnitude 7.5 earthquake and a series of large aftershocks.
Mr Key and his wife were at Premier House in Wellington when the quake hit just after midnight on Monday.
"I mean, it's not unusual to get quakes here but then it started building in its intensity and people will appreciate Premier House's been built a long time ago so it's a structure that really rattles around," he told reporters at Parliament House hours later.
"I just know from going through the Christchurch earthquake just how much it undermines people's confidence and the most important thing we can do at the moment is just get them reassurance that the support will be there for them."
Mr Key has not called a national emergency saying the country's 16 regions have activated their own civil defence requirements as aftershocks continue.
He confirmed two people have died, but said phone lines were effected in the North Canterbury region making communication difficult where the main quake struck difficult.
Source: AFP
A military helicopter will be sent to Kaikoura to re-establish communications.
"As soon as we can get a much better assessment of the actual damage then we can work out the next steps from here," he said.
Mr Key said he wasn't concerned about the government's capacity to fund major repairs that will no doubt be necessary.
"We know that from Christchurch, the movement in the earth at this sort of magnitude, it damages the core infrastructure more than you're initially aware of and it's more expensive to rebuild," he said.
Three cows stranded on an island of grass in a paddock that had been ripped apart following an earthquake near Kaikoura, New Zealand, Nov. 14, 2016. Source: AAP
"But we're quite within our financial capacity to deal with that."
He urged people across the country to continue to monitor media for warnings.
