Christchurch rocked again by aftershocks

STRONG aftershocks have hit New Zealand's earthquake-ravaged city of Christchurch, toppling one of the few central buildings still standing and plunging thousands of homes into darkness.

Bricks crashed down in the cordoned-off city centre yesterday, where only workers have gone since it was devastated in February's major earthquake.

About 200 people were there when the aftershocks struck, and two were briefly trapped in a church.

More than 40 people have been taken to hospitals with minor injuries from falling debris, the city council said.

"We are being enveloped with dust," Christchurch mayor Bob Parker said. "It is very, very scary."

All across the city, people fled buildings in panic when a magnitude 5.2 earthquake struck during lunchtime. Just over an hour later, a magnitude 6 hit, according to the US Geological Survey. Smaller tremors were also recorded.

Several buildings were damaged in the city centre and suburbs.

"All the shops have fallen down," said Renee Murray, who works at a pizza shop in a suburb. "Half of the roof has fallen in but they have not fully collapsed."

Thousands of aftershocks have followed the magnitude 6.3 earthquake that killed 181 people on 22 February. That tremor and its aftershocks have been very shallow, which along with proximity to the city, have made them very destructive. Yesterday's tremors were six miles deep, according to the USGS.

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About 47,000 homes in the city's eastern suburbs were without power last night, with temperatures expected to approach freezing.

Rocks tumbled down hills in the area, which was among the hardest hit in February, and silt bubbled from the earth - a process known as liquefaction that sometimes happens during an earthquake.

After the February earthquake, 300,000 tons of silt had to be scraped away, and the silt alone made thousands of homes uninhabitable.

On one road yesterday, a large car tipped front-first into a hole that opened in the asphalt. A police car sank into another.

Roger Sutton, chief executive of the Canterbury Earthquake Recovery Authority, said the extra damage to the city centre means some buildings that had been salvageable "are now seriously damaged and will have to be brought down".

The group's demolition manager "was driving (during the magnitude 6 quake], and there were buildings coming down in front of him, coming down behind him," Mr Sutton said.

"He's very lucky to be alive."

Two people who were injured were salvaging windows from St John's Church when the facade, the last wall standing after February's earthquake, collapsed. Police said they were rescued and taken to a hospital with cuts and bruises.Another building nearby fell, according to police, and the dean of Christchurch Cathedral said the collapsed building suffered new damage.

"This has been a setback for Christchurch and its people, but it does not lessen our resolve to rebuild," prime minister John Key said. "The people of Christchurch should know all New Zealanders are thinking of them and will continue to support and stand by them in this very difficult time."

New Zealand's earthquake monitoring service said yesterday that more aftershocks overnight had followed the two main quakes, the largest measuring magnitude 4.7.