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