The worst quakes are over - experts

Scientists say it could be thousands of years before the faults responsible for Christchurch's devastating earthquakes ruptured again. Photo / Greg Bowker

Scientists have given reassurance to weary Christchurch residents that the worst of the earthquakes is likely to be over.

On day two of public hearings for the Canterbury Earthquakes Royal Commission of Inquiry today, experts said the evidence showed that the quakes that have plagued the city since September last year are historically rare. However they cautioned there are still unknowns.

The commission is investigating why buildings failed in the Christchurch quakes, including the February quake that claimed 182 lives, and how to prevent such a tragedy happening again.

Statistical modelling as of last month presented by GNS Science showed that there was roughly a 14 per cent chance of another quake in the range of magnitude 6 over the following year.

It is the quakes over magnitude 6, such as that in February, have caused the death and widespread destruction in Christchurch.

"It's something we really shouldn't be living in fear of," said director of the Natural Hazards Division of GNS Science, Dr Terry Webb.

Head of the Department of Geological Sciences at Canterbury University, Professor Jarg Pettinga, said the rupture of faults in the earth beneath the Christchurch area that caused the large quakes did not happen often.

"It takes quite some time for those stress levels to build up again (in the faults) to critical levels," Dr Pettinga said.

It could be thousands of years before those faults responsible for the Christchurch quakes ruptured again, he said.

But while some faults had been identified, there could be others experts did not know of that might have stress built up over thousands of year.

"We don't have the complete picture," Dr Pettinga said.

The first of 11 hearings in the inquiry, based on evidence about seismic activity, is expected to continue through to tomorrow. The commission must deliver its report to the Government by April 11 next year.