A man who has more than a dozen close friends and colleagues missing in earthquake-devastated central Christchurch says all he can do is wait and hope they are still alive.

Richard Lord had until recently worked for regional television station CTV, which is based in one of the worst-hit buildings in the 6.3 magnitude quake that hit yesterday, claiming at least 75 lives.

Some of the occupants of the CTV building have been freed alive, while others have been confirmed dead and many are still missing.

There have been conflicting reports on news bulletins and websites that there may be up to 15 people still alive in a pocket in the wreckage, and that all hope of finding more survivors is lost.

Mr Lord, an employee of three years at CTV, said the workforce was a "notoriously tight bunch".

"It's very difficult waiting and not knowing," Mr Lord said.

"You do whatever you can to try to find information and try to get in touch with the people who were okay and managed to get out. We know some are okay, but we don't know anything more about the other people."

"We can only hope that there are many pockets in that rubble and that by pure chance people have been able to survive in there. When you're down there and you see how flattened it is, you can't help but feel your heart sink. How could it be possible?"

Reports of people sending text messages from within the wreckage had given some faint hope, but no certainty.

"It's more difficult when you try and ring all those people that are missing, you try and ring their cellphones and you're not getting an answer and nothing is getting though."

Mr Lord realises he could easily have been in the building himself if circumstances had been a little different.

"That certainly goes through your mind pretty quickly. It makes it more difficult to deal with when you realise that others weren't as fortunate. I feel like I should do everything I can to get as much information as I can."

He was down at the building site last night, where family members of the missing were also waiting. A man was pulled out alive while he was there, but Mr Lord did not know him.

Maurice Gardiner, the brother of missing CTV employee Donna Manning, said he had just been relieved from his part digging at the site of the collapsed CTV building. People were working as hard as they good but had not had any positive result.

"We pray for hope and we prepare for something that won't work out, obviously. We are just doing what we can until we get a definitive answer one way or another. We always look for the hope in things, don't we.

Mr Gardiner said his and Mrs Manning's elderly parents were struggling with having no news on top of being without power at their own home.