Following the quake, a tsunami alert of up to 1 meter was issued for a wide area of Pacific coast including Australia, Chile, Ecuador and Peru, according to the Hawaii-based Pacific Tsunami Warning Center.
Japan s weather agency said sea-level changes could occur on the country s coastline but there will be no tsunami.
Before the magnitude 8.1 quake, two powerful earthquakes also struck off New Zealand, triggering a small tsunami on the island country.
Following the first quake, which hit with a magnitude of 7.3 at 2:27 a.m., a tsunami of up to 28 centimeters was observed at the North Island.
The USGS upgraded the magnitude of the first temblor, which occurred 178 kilometers northeast of the North Island at a depth of 10 km, to 7.3 from an initial estimate of 6.9.