The quake, which struck at 10:33 am (2233 GMT Sunday) was centered at sea nearly 200 kilometers (120 miles) from the eastern North Island city of Gisborne and 35 kilometers deep, the US Geological Survey said.
New Zealand’s civil defense organization said it was “unlikely to have caused a tsunami that will pose a threat to New Zealand”.
GeoNet, the New Zealand earthquake monitoring service, rated the tremor as “severe” and said it was widely felt throughout the lower North Island and top of the South Island.
However, it was too far off shore and too deep to cause any damage on land, a spokesman said.
Earthquake-prone New Zealand sits on the edge of the so-called Pacific “Ring of Fire” where continental plates collide, causing frequent seismic and volcanic activity.
The country experiences about 20,000 tremors a year, with an average of 2.5 of magnitude 6.0 or higher.
In 2011, 185 people were killed when a devastating 6.3-magnitude quake hit the South Island city of Christchurch in one of the nation’s deadliest disasters of the modern era.
Wellington was the scene of the country’s most powerful earthquake in 1855.
That devastating 8.2-magnitude quake caused four deaths and changed the city’s entire geography, pushing the shoreline out 200 meters (660 feet) as it thrust the harbor floor upwards.