The Christchurch earthquake rebuild could cost as much as $30 billion, but could make Christchurch the construction hub of New Zealand for the next decade, say industry heads.

Estimations the earthquake repair work would cost $20b was "very light" and it could easily reach $30b, Canterbury Employers' Chamber of Commerce chief executive Peter Townsend told Fairfax Media.

Economists and others who originally calculated the bill at $20b were already revising their figures upwards, he said.

"When you start adding up what has happened, what needs to be done, the scale of this thing is just massive. It's mind-boggling. I think $30b is more than possible," Mr Townsend said.

Fletcher Building infrastructure chief executive Mark Binns said the February 22 earthquake had changed the scale of the problem facing construction companies and others involved in repairing and rebuilding.

"The event of February 22 was a game-changer. There will be massive implications for the industry over the next decade," he said.

Everyone would have to re-evaluate how work around the country was rolled out and the resources required, he said.

"It's a pretty intensive programme over the next decade that will need planning."

Meanwhile, the director of documentary made 15 years ago warning Christchurch of the effects of a major earthquake said lives could have been saved if officials had listened to the film's warnings.

The 1996 made-for-television film Earthquake! warns that Christchurch's "fatal flaw" was the "soft, shaky sponge of riverstones and silt" Christchurch sat on.

"In any decent quake, the Garden City will shake like a leaf," it said.

It also successfully predicted that liquefaction would wreck sewers and drains, break up roads and cause buildings to sink or tip, especially in the eastern suburbs, which were hard-hit by the February 22 quake.

Documentary director Grant Dixon said Earthquake! rated well but was greeted with "a deafening silence" from officials.

He regretted not making his point more forcibly.

"In hindsight, I should have gone and sat outside the mayor's office and demanded that something happened."

Meanwhile, more parts of central Christchurch were expected to be re-opened to business owners and residents today as the last of three "green zones" in the earthquake-ravaged city opens.

However, an orange zone may not be reopened for some weeks and the seriously damaged red zone remains closed.

The future of rugby World Cup games in Christchurch remain uncertain as the Government mulls over engineering reports on damage to AMI Stadium and its ground, described by Christchurch Mayor as like a "putt putt golf course".

Rugby World Cup Minister Murray McCully said a decision on whether the city could host five pool matches and two quarterfinals could be made as early as next week.

The International Rugby Board has the final say on whether games in Christchurch will go ahead.

In Parliament last night legislation was passed unanimously allowing a one-off provincial holiday in Canterbury so people can attend a memorial service next Friday for those killed in the quake.

The official death toll yesterday remained at 166 and police have so far named 83 of the dead. The toll is expected to rise to at least 200.