Monday, 6 September 2010

7.1-magnitude quake that rocked New Zealand earthquake occurred on previously undetected fault line


By James White

Cracking fun: Children climb in a hole caused by the earthquake in Christchurch, New Zealand. It occurred on a previously-undetected fault line

The New Zealand earthquake occurred on a new fault line or one which was previously not detected, an expert revealed today.

Homes and businesses in Christchurch, New Zealand, were badly damaged by the 7.1-magnitude tremors which initially left geologists baffled.

It is now thought the earthquake's epicentre occurred in an area which had not previously shown tectonic movement.

Dr Mark Quigley, of Canterbury University, said: 'Preliminary investigations suggest that the fault was not previously recognised as a major earthquake source because it resides under the Canterbury Plains and had no prior visible geomorphic expression.

'However, Canterbury University scientist Jarg Pettinga predicted the presence of such faults in a paper published 12 years ago.'

He said there was a foreshock measuring 5.6 on the Richter scale and predicted many further aftershocks to come, decreasing in intensity.

Further mapping of the fault line will take place in coming days before evidence is lost, he added.

No-one died in the earthquake and only two people were reported injured, resulting in claims that tough buildings had saved lives.

However, damage to infrastructure will hurt the country's economic recovery following 18 months of recession, the New Zealand Prime Minister said.

Coming down: A mechanical digger is used to demolish a damaged building in Christchurch, one of 500 which have been condemned in the wake of the powerful quake

Checking: A search and rescue dog is used to look for anyone possibly trapped by rubble

'There will be considerable disruption to the (regional) and national economy in the short term,' John Key said.

After a tour of the affected areas, Mr Key said about 100,000 of the region's 160,000 homes had sustained some damage, he said.

'I was awe-struck by the power of the earthquake and the damage it has caused in the city. It was miraculous that nobody was killed.'

Soldiers have joined efforts to secure central Christchurch as 430 houses and 70 older buildings were earmarked for demolition.

More than 80 aftershocks, ranging from magnitude 3.2 to 5.4, have rocked the region since the major tremor on Saturday.

Rain was falling today in the nearby Southern Alps and foothills, increasing the risk of flooding. Civil defence officials warned that stop banks, or flood protectors, weakened by the quake may fail to hold rising waters.

Demolished: A building being pulled down is centre of attention for people living by in Christchurch

The Pacific plate is gradually being pushed beneath the Australian plate, which caused the massive earthquake

New Zealand sits above an area where two tectonic plates collide. The country records more than 14,000 earthquakes a year - but only about 150 are felt by residents. Fewer than 10 a year do any damage.

New Zealand's last major earthquake registered magnitude 7.8 and hit South Island's Fjiordland region on July 16, 2009, moving the southern tip of the country 12in closer to Australia.


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