The Pacific Tsunami Warning Centre based in Hawaii, believes New Zealand's Civil Defence could have handled yesterday's alert better, but is taking a look at its own systems.

Civil Defence is being criticised for being too slow to react to the emergency but centre geophysicist Gerard Fryer says Civil Defence was quick to respond and knew exactly what was going on. However, he admits there is probably room to improve communications with the public.

He says the government agency should have issued a clarification, explaining exactly how serious the situation was. Mr Fryer says his organisation will make its warnings simpler to understand, so that there is no confusion in the future. He says it is rare for the centre to put out tsunami warnings and they should be taken seriously.

Meanwhile, the latest quake, which hit Tonga at 12.25am today, has not triggered a tsunami warning.

It measured six on the Richter scale. Yesterday's jolt was magnitude 7.8.