The director of GeoNet has detailed responding to the "monster" magnitude 7.5 earthquake that rocked the country early Monday morning.

In a post on the GeoNet website, Dr Ken Gledhill said "it feels like central New Zealand is getting a hammering by our most brutal project manager: nature".

"It was a monster quake, one that has shocked us all with its intensity and ferocity. Because of its size it made our world shake strongly but relatively slowly for a long time.

"It is a complex, brooding beast we are still trying to understand. Although we published information on it very quickly, please forgive us as we tell you more and revise what we have already told you."

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Gledhill said there needs to be a round-the-clock monitoring centre for geographical hazards.

"But, even with a 24/7, we may still not have been fast enough for people in Kaikoura. The best advice is still: if you are at the coast, and feel a long or strong earthquake, be gone.

"For those pople who took those brave steps in the middle of the night of the tsunami, I applaud your efforts. You did the right thing.

"For people who were further away and waited but left once told to evacuate. You also did the right thing. We were lucky the tsunami struck at low tide; high tide could have left more damage than I feel comfortable thinking about."

Gledhill praised Kiwis who were "prepared, tough and able to cope with almost anything".

" It is perfectly acceptable to be scared by this earthquake but we will get through this by doing what I think Kiwis do best: helping each other.

"We saw this with the Canterbury earthquakes and we are seeing this again. We are also good at taking care of our visitors and our new Kiwis as well."

The full message can be read here.