Civil Defence wants to know why New Zealand was removed from an international tsunami warning list when officials in this country maintain the tsunami threat following Japan's earthquake had continued.
On Friday night, the Pacific Tsunami Warning Centre in Hawaii removed New Zealand from its list of countries that could be affected, although Civil Defence continued to advise that waves of up to 1 metre in height could affect parts of the coast.
The official alert from New Zealand authorities was not cancelled until Saturday night.
Civil Defence national operations manager David Coetzee says the organisation does its own modelling which is more refined towards New Zealand's circumstances.
He says the Pacific Tsunami Warning Centre's decision was puzzling, and his organisation will be following up to find out what happened.
The largest wave recorded for New Zealand was in the Chatham Islands and had a height of 90 centimetres, which Mr Coetzee says close to what the experts' modelling had predicted.
Civil Defence also says it is disappointed some people went to the beach on Saturday, despite warnings of the tsunami threat to New Zealand after the earthquake in Japan.