A tsunami expert in the United States is urging New Zealand to install deep sea warning devices off the east coast of the North Island.
Professor Costas Synolakis, from the University of Southern California, says tsunamographs record changes in water pressure in the deep ocean.
He says there are already a number throughout the Pacific, but none directly to the east of New Zealand.
If they were deployed off the east coast of the North Island, Professor Synolakis says they would provide extra minutes of warning time and accurate information on the size of waves.
But GeoNet, the agency which monitors seismic activity, says the cost of their installation would outweigh the benefits because data relating to quakes close to New Zealand would not arrive in time to be of use. NIWA agrees.
The devices cost about $300,000 each, plus a similar amount each year for maintenance.