Christchurch hit by new shocks

Damage and injuries were minor compared to the 22 February  disaster, but it brought power cuts and spread fear among a frightened and weary population.

St John's Ambulance reported that six people were taken to hospital; two people were rescued from a collapsed building, and 54,000 homes lost power.

The US Geological Survey measured the biggest tremor at 6.0; it struck at a depth of 5.6 miles and some nine miles from the country's second largest city.

An hour and twenty minutes earlier buildings were evacuated following a 5.2 magnitude quake. Much of the centre of the city is still sealed off because of the precarious state of many damaged buildings from four months earlier.

That disaster was technically an aftershock from an earthquake last September, and for nine months its residents have endured thousands of tremors.

Christchurch mayor Bob Parker was on the telephone to Sky News Australia and describing the earlier tremor live on air when the 6.0 quake shook his office. He sounded scared as he described what it was like, and cut short the interview.

The aftershock prompted police to evacuate parts of the damaged central city known as the red zone, while rock falls had closed several bridges and prompted the closure of one police station.

Eastern suburbs were badly affected by flooding and liquefaction - mud oozing from below the surface and covering roads.

Police urged residents to check on friends and neighbours, and to stay at home and avoid travelling if possible, but residents gridlocked the roads as they attempted to find their way home and reach family.

The series of quakes forced the adjournment of an inquest examining why the CTV building collapsed in February's earthquake, killing more than 100 people, including 65 foreign students.

Geoscience Australia seismologist David Jepson said people would have been shaken quite strongly after New Zealand's South Island had endured much seismic activity in recent months.