Christchurch building demolished

The country's first building implosion went without a hitch in quake-damaged Christchurch today but so far no other building owners were looking to do the same, says Cera.

In a dramatic scene, the 14-storey Radio Network House was reduced to dust and rubble in nine seconds this morning.

Online bidders had previously vied for the chance to press the button that would set off 60kg of explosives in the building - an honour that ultimately went to six-year-old Jayden Halliwell.

The explosion went exactly as planned, said Pete Lockhart, regional manager for Naylor Love which was responsible for the demolition.

He said a number of other alternatives were initially considered for demolishing the building, including high-reach demolition and cut-and-crane demolition.

"However, once we took into account all the factors, including the short amount of time an implosion takes, it was considered the most appropriate option, particularly as there are not many other buildings close to Radio Network House,'' he said.

It was up to owners to decide how to demolish their buildings but if they wanted to use implosion, there were a number of Cera criteria to meet to ensure it could be done safely; including making sure there would be no impact on other buildings, said Earthquake Recovery Authority (Cera) chief executive Roger Sutton.

CERA was not aware of any other owners looking to use implosion, said Mr Sutton.

Jayden Halliwell, who has kidney cancer and is in Christchurch for chemotherapy, was gifted the opportunity to press the button starting the implosion by several construction companies that won a TradeMe auction with a $26,000 bid.

"It was a real honour that they picked Jayden to do it. I think he really enjoyed it,'' his mother Justine Swain said.

Thousands of people gathered in Latimer Square to watch the collapse.

"It was almost like it was in slow motion; you could see the explosions go off and it slowly started to come down,'' said Ms Swain.

"There was a lot of smoke and dust when it came down, it was pretty amazing to watch.''

One of the building's owners, Greg Hedges, said the demolition could be seen as symbolic of a new dawn for Christchurch.

However he had mixed emotions about seeing a building which had been an important feature in his life turned to dust.

"It was an interesting spectacle, not one that we as owners wanted to see, really. It's a sad occasion to see something you've built up being destroyed, but now we can all look forward to something better going in its place, so we've just got to move on.

"As it came down a massive plume of dust came up and covered surrounding buildings and all the people who had assembled to watch, but it quickly dissipated in the wind,'' Mr Hedges said.

Cera said the dust had not caused any problems in the area.

Proceeds from the demolition auction will help to restore the Isaac Theatre Royal and other Canterbury heritage buildings, with the Government matching the bid amount.