Experts: 13pc chance of a 6.0 Canterbury quake

Christchurch was riddled with damage after the quakes. Photo / Geoff Sloan

Experts have calculated that the risk of further damaging earthquakes in Canterbury is now about 20 per cent less than previously forecasted.

GNS Science today said that top scientists from New Zealand, Australia, Ireland and the United States had combined to look at the future risk of aftershocks in the wake of the earthquakes that have devastated Christchurch in the last 18 months.

"Nothing has changed inside the earth to increase or decrease the risk of an earthquake,'' said GNS scientist Dr Kelvin Berryman.

"It's just that we have used additional data and incorporated feedback from international specialists to make adjustments in the way the probabilities are calculated.

"Earthquakes will continue to be a feature of the Canterbury region over the coming decades.''

The experts now put the probability of a magnitude 7 or higher quake at one per cent in the year from January 15, which is unchanged from previous forecasts.

The risk of a magnitude 5.0 to 5.4 quake is put at 82 per cent, down from 92 per cent in the previous forecast.

The risk of a 6.0 to 6.4 aftershock over that period is put at 13 per cent, down from 17 per cent in the previous forecast.

Dr Berryman said the potential for future quakes centred under Christchurch city

would eventually be exhausted.

Earthquake Recovery Minister Gerry Brownlee said building standards in Christchurch during the city's rebuild would incorporate the risk of further earthquakes.

"It's far better to be really realistic about might happen so we can be well prepared against that probability.''