All of New Zealand's coasts were hit by tsunami waves following Japan's massive magnitude 9.0-magnitude earthquake last Friday, the National Institute of Water and Atmospheric Research (Niwa) says.
Its data revealed a tsunami wave even registered on a sea-level gauge at Scott Base in Antarctica.
Niwa's 19 sea-level gauges showed peak wave amplitudes, or the height of the wave above predicted tide levels, ranged from 0.78m at Whitianga, the Chatham Islands and Timaru to just 5cm at Scott Base.
Whitianga and the Chatham Islands received the largest waves at 1.6 metres, while Mount Maunganui, Charleston, near Westport, and Timaru also recorded wave heights over a metre.
The peak wave amplitude was an important way to assess the tsunami hazard on land from a sudden surge in water above predicted tide levels, Niwa said.
The height of the wave, from the crest to the trough, provided information about the possible tsunami danger -- for example, how boat moorings, mussel farms or ports would be affected by surging currents.
The first waves to hit New Zealand, after the earthquake struck Japan, did not arrive until at least 12 hours later.
In Timaru and Christchurch the largest waves did not hit until up to 40 hours after the first quake-generated wave.
