Phil Mercer | Sydney 05 September 2010

Rubble and debris lie in front of a damaged business following Saturday's powerful 7.1-magnitude earthquake, in Christchurch, New Zealand, 5 Sept., 2010.

New Zealand's second-biggest city, Christchurch, is facing an enormous clean-up after being struck by the country's worst earthquake in 80 years.  The magnitude 7 quake devastated parts of Christchurch early Saturday.

Christchurch awoke Sunday to another grim day as shell-shocked residents assess the damage inflicted by one of the country's most powerful earthquakes.

Mayor Bob Parker is urging residents to stay indoors.

"This is not a good time to go out, as curious as you may be, and have a look around if it means driving out onto the streets because we need to keep them free for emergency services," Parker advised. "Use common sense; emergency services are flat out at the moment. The assessment is underway. Take sensible precautions, but don't go out sightseeing. Check on your neighbors. Do the things that communities do so well at times like this."

Authorities say it is a miracle no one was killed after disaster struck Saturday before dawn, when most people were still asleep.  A small number of serious injuries have been reported.

Roads and bridges have been left in ruins and troops are expected to be deployed to help in the emergency effort.  Power and water supplies have also been disrupted.  Authorities say the clean-up will be long and expensive.  The damage bill is estimated at about $1.5 billion.

A night time curfew was imposed in parts of Christchurch, while schools offered emergency shelter to those left homeless.

A series of aftershocks have unnerved a wary population.

New Zealand sits on the so-called Pacific Ring of Fire, a vast area of unpredictable seismic activity.  The South pacific country of more than 4 million people experiences more than 14,000 earthquakes each year.  Most are minor but occasionally nature displays its destructive power.

This weekend's earthquake is among the 10 strongest the country has ever recorded.