http://www.bbc.com/news/world-asia-37967178The US Geological Survey said the magnitude-7.8 quake hit just after midnight (11:02 GMT on Sunday), some 95km (59 miles) from Christchurch.
The ministry of civil defence has warned a tsunami may hit the eastern coast of the North Island "shortly".
Residents have been told to head inland or for higher ground along the entire eastern coast.
"The first wave may not be the largest. Tsunami activity will continue for several hours," the ministry tweeted.
New Zealand lies on the notorious Ring of Fire, the line of frequent quakes and volcanic eruptions that circles virtually the entire Pacific rim.
Christchurch is still recovering from the 2011 earthquake that killed 185 people and destroyed the city centre.