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First look inside collapsed Christchurch Cathedral

22 February 2011 Last updated at 19:16 GMT

A New Zealand TV reporter has been inside the country's earthquake-hit Christchurch Cathedral, which was badly damaged by a 6.3-magnitude quake on Tuesday.

Christchurch Mayor Bob Parker says more than 100 people are feared buried in collapsed buildings in the city.

The disaster struck at a shallow depth of 5km (3.1 miles) at lunchtime when Christchurch was at its busiest.

The BBC's David Shukman looks at why the disaster has been so devastating.