New Zealand earthquake 'has ripped new 11-mile faultline into the Earth'

The powerful earthquake that smashed buildings, cracked roads and twisted rail lines around the New Zealand city of Christchurch also ripped a new fault line in the Earth's surface, a geologist has said.

At least 500 buildings, including 90 in the downtown area, have been designated as destroyed by the 7.1-magnitude quake that struck in the early hours of Saturday near the South Island city of 400,000 people. Most other buildings sustained only minor damage.

Only two serious injuries were reported from the quake as chimneys and walls of older buildings were reduced to rubble and crumbled to the ground. Prime minister John Key said it was a miracle no-one was killed.

Part of the reason the city escaped major injuries was because the quake happened before dawn, Mr Key said.

"If this had happened five hours earlier or five hours later (when many more people were in the city] there would have been absolute carnage in terms of human life," he said last night.

The quake cut power across the region, blocked roads with debris, and disrupted gas and water supplies, but Christchurch Mayor Bob Parker said services were being restored.

As the recovery work gathered pace, forecasters warned strong winds would buffet the area, creating problems with flying debris.

WeatherWatch forecaster Philip Duncan said gale force winds of 40mph and stronger "could cause serious issues for trees and buildings that were weakened in the earthquake".

Specialist engineering teams began assessing damage to all central city buildings yesterday, said Paul Burns of the city's search and rescue service.

Canterbury University geology professor Mark Quigley said what "looks to us that it could be a new fault" had ripped across the ground and pushed some surface areas up. The quake was caused by the ongoing collision between the Pacific and Australian tectonic plates, said Prof Quigley, who is leading a team trying to pin down the source of the quake.

"One side of the earth has lurched to the right - up to 11 feet - and in some places been thrust up," he said. "The long linear fracture on the earth's surface does things like break apart houses, break apart roads.We saw two houses that were completely snapped in half by the earthquake."

Euan Smith, professor of Geophysics at Victoria University, speculated that the very soft soils of Christchurch had "acted like a shock absorber over a short period… doing less damage to smaller buildings".

Mr Key, who flew to Christchurch to inspect the damage, said the city "looks like something off a movie set", with wrecked buildings, buckled roads, broken water mains and sewage systems and some flooding.

Scientists from GNS Science began installing 40 portable seismographs in the region yesterday to record seismic data from the continuing stream of aftershocks. More than 60 had been recorded by mid-afternoon.

Seismologists study aftershock sequences to help learn more about the mechanics of the main quake, and to check whether stress in the Earth's crust has been transferred to other faults in the region.

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 ten a year do any damage.

New Zealand's last major earthquake registered magnitude 7.8 and hit South Island's Fiordland region on 16 July, 2009.