Worst tremors probably over: scientists

Terry Webb.
Terry Webb.
Scientists have reassured weary Christchurch residents the worst of the earthquakes is likely to be over.

On day two of public hearings for the Canterbury Earthquakes Royal Commission of Inquiry yesterday, experts said the evidence showed the quakes that have plagued the city since September last year are historically rare.

However, they cautioned there were 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 there was roughly a 14% chance of another quake in the range of magnitude 6 over the following year.

It is the quakes of more than magnitude 6, such as that in February, that have caused the deaths and widespread destruction in Christchurch.

"It's something we really shouldn't be living in fear of," Terry Webb, director of the natural hazards division of GNS Science, said.

Canterbury University department of geological sciences head Prof 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 the 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.

The commission must deliver its report to the Government by April 11 next year.

 

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