Active Planet: Christchurch suffers another major earthquake

There are fires burning in the centre of Christchurch and in the surrounding countryside. As firemen, police officers and office workers, some still wearing their jackets and ties, scramble around, over and into buildings to try to reach the stranded or trapped, fire trucks are called away from rescue to put out fires and aircraft water-bomb the forests around the city.

Phone lines are almost all cut, electricity is broken or shut down for much of the city centre, mains gas has been turned off with New Zealand television broadcasting messages reminding anyone who can hear to turn off all gas appliances and, ideally, the mains before leaving the building.

But many people can't leave: the are "multiple" deaths - how many is not known and will not be for some time.

Two buses have been discovered under rubble; a backpacker who had parked his van in the city was killed when it was crushed; debris has destroyed cars as they were driven along the road.

Christchurch Cathedral, a gothic masterpiece, has suffered major damage as the spire collapsed. The number of people inside is not known.

Several office blocks have collapsed: people inside have used mobile phones to provide their location.

The roads are buckled, water mains are flooding the streets and petrol stations have closed because it is not known whether there may be damage to tanks and piping.

The city has run out of ambulances: individuals have driven into town to put their 4x4s at the disposal of the emergency services.

As emergency crews extract victims, they are being passed from hand to hand, carried out by office workers who were not in the buildings when they collapsed.

The airport is closed until further notice: Singapore Airlines says "disruptions to our operations are expected" and warns travellers not even to go to the airport.

Within two hours of the earthquake hitting, the NZ dollar fell 1% against the USD.

Across New Zealand, EFTPOS services are disrupted.

The earthquake was not so severe as the largest last September. That was 7.1 magnitude. The most powerful aftershock - really a second earthquake in its own right - was more than 5. Today's was 6.3.

But it was much closer to the city - just 10km outside - and at a much shallower depth - just 5km. That caused a serious "wave effect" across the landscape.

The Central Business District was apparently relatively unscathed in the previous earthquake. But not this time: it has taken the full force of the wave as it rushed through the city and into the sea.

Rescuers are working against the clock: it's not just that it is (at the time of writing) late afternoon and night is approaching but also recent history suggests that they may be many, including severe, aftershocks which will increase the danger and reduce the prospects of successful extractions.While this article was being written an aftershock of an estimated 5.3 has hit, this time centred only 5km from the city raising fears that even closer shocks are on the way.

We, ourselves, have a programming team based in Christchurch and, at the time of writing, have not been able to make contact with them. We wish for their safety.