A tsunami generated by a large earthquake off the Solomon Islands could pose problems for people on the water in New Zealand, but is unlikely to cause any damage on land.

The Ministry of Civil Defence issued a potential tsunami threat for North Cape, Auckland, East Cape, Gisborne, New Plymouth and Wellington following the magnitude 8.0 earthquake near the Santa Cruz Islands, part of the Solomons, about 2.12pm local time (1212 AEDT).

Civil Defence director John Hamilton said a tsunami of about 90cm had been generated and was likely to reach North Cape between 6pm and 7pm.

"It's not a damaging tsunami but a disturbance in the water which we classify as a marine threat," he told a media conference.

"If there's boating activities, people who are swimming, and particularly people in estuaries and restricted harbours, they could experience stronger currents and tidal activity which could be a danger to them.

"Local authorities are warning people to be wary, but there is unlikely to be any damaging activity to the shoreline buildings."

The ministry said the first wave may not be the largest, and that waves could continue for several hours.

It said people should not go sightseeing, should stay away from beaches and out of water, share the information with friends and family and listen to radio and television for instructions.

The Pacific Tsunami Warning Centre in Hawaii issued a tsunami warning for the Solomon Islands, Fiji, Vanuatu, Nauru, Papua New Guinea, Tuvalu, New Caledonia, Kosrae, Kiribati, and Wallis and Futuna.

A tsunami watch was issued for several more distant islands, including New Zealand.

It cancelled the warnings and watches, including the watch for New Zealand, by 4.50pm (1450 AEDT) on Wednesday.