Nobody can predict when an earthquake will strike, the Prime Minister's chief science adviser says.

The Government and the Royal Society of New Zealand today released a scientific paper at a briefing in Wellington, looking at earthquake predictions and future earthquake risks for Christchurch and New Zealand.

During the briefing, Sir Peter Gluckman hit out at Ken Ring's controversial prediction that another big quake will hit Christchurch on or near March 20.

"There's no added risk of a quake on March 20 or any other day and I think people do not realise the disharmony and the discomfort that is being given to a lot of people in the Christchurch regions by (predictions)," he said.

It was inevitable smaller quakes would rock the region on a daily basis.

"Inevitably there will almost certainly be aftershocks of low magnitude in Canterbury on March 20th as there are today, tomorrow, and most days over the next two weeks," he said.

Scientists could identify regions vulnerable to quakes and predict the likely magnitude of a quake but not the precise locality, depth or timing, he said.

"Certainty as to a particular event or outcome just cannot be achieved. What therefore may happen, can only be described in terms of risks and probability."

Christchurch's deadly quake on February 22 has raised fears of another big quake and Sir Peter seemed eager to quell any rumours and predictions.

"Scientifically there's no reason not to rebuild in Christchurch...although soil degradation means some sites may not be sensible or economic to rebuild on," he said.

Although aftershocks were distressing, the risks of "major impacts" in Christchurch was steadily declining, he said.

However, New Zealand was clearly home to an active and unstable landscape.

"We've obviously all been reminded, tragically and vividly over the last few months, that we're living in a world that is not static."

"There is a wide range of scientific effort already under way and being planned to help Christchurch and New Zealand as a whole to design, plan and build the engineering needed to deal with the risks we face," he said.

Earthquakes were not increasing in frequency around the world and there was no relationship between the deadly quakes in Christchurch and Japan, he said.

Nor was there any reason for New Zealanders to fear radiation poisoning from an nuclear explosion in Japan, he said.

GNS Science general manager of natural hazards Terry Webb said many Christchurch buildings appeared to have withstood the massive earthquake on February 22 very well, despite the shaking exceeding building standards.

GNS Science chief executive Alex Malahoff and Royal Society of New Zealand vice-president Keith Hunter were also on the panel.