New Zealand witnessed its first controlled implosion on Sunday, as a 14-storey office tower in Christchurch came tumbling down.

US demolition experts used 60 kilograms of explosives to blow up Radio Network House, once home to 400 office workers, but was badly damaged during the magnitude 6 point 1 earthquake last year.

The implosion is reported to have cost about 1.2 million US dollars.