The quake struck at 9:20 am (0250 IST), 370 kilometres north of Raoul Island in the Kermadec islands at a depth of 280 kilometres, the USGS said.
No tsunami warning was immediately issued by the Pacific Tsunami Warning Centre.
Earthquakes and volcanic activity are common in the area, which is part of the "Ring of Fire" where the Pacific plate of the Earth's crust meets other continental plates.
The Kermadec islands, 1,000 kilometres north of New Zealand, are uninhabited apart from Raoul, where New Zealand's Department of Conservation maintains a field station.
Deccan Herald is on WhatsApp Channels| Join now for Breaking News & Editor's Picks