New Zealand's Civil Defence warned residents along the country's entire east coast to seek higher ground.
Anna Kaiser, a seismologist at GNS Science said a tidal signal or surge of up to one meter (3 feet) had been recorded in North Canterbury region of the South Island.
Prelim M7.4 earthquake South Island of New Zealand Nov-13 11:02 UTC, updates https://t.co/M2j6JZgiQT
— USGS Earthquakes (@USGS_Quakes) November 13, 2016
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"It was massive and really long," Tamsin Edensor, a mother of two in Christchurch, told AFP, describing the powerful quake as the biggest since the deadly 2011 tremor.
"We were asleep and woken to the house shaking, it kept going and going and felt like it was going to build up."
In a brief message the Prime Minister John Key tweeted: "I hope everyone is safe after the earthquake tonight."
The ambulance service said it did not receive any reports of quake-related injuries.
However, the national civil defence organisation, which is in charge of New Zealand's emergency management said a tsunami was possible.
"The first wave activity may not be the most significant," it said in a bulletin, adding tsunami activity would continue for several hours.
Anna Kaiser, a seismologist with the GNS Science, said the government's earthquake monitoring service, the quakes were close to the coast.
"They've been quite large. We've also seen a signal on the tide gauge at Kaikoura which is up to one metre (three feet) so it's reasonably significant, so people should take this seriously."
However, the Pacific Tsunami Warning Center said that based on available data "a destructive Pacific-wide tsunami is not expected."
In September, a strong 7.1-magnitude earthquake struck the east coast of New Zealand, generating a small tsunami, but no significant damage or injuries were reported.
New Zealand is on the boundary of the Australian and Pacific tectonic plates, which form part of the so-called "Ring of Fire", and experiences up to 15,000 tremors a year.
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