Distraught Christchurch residents who have evacuated their damaged homes are now left wondering when their lives could possibly return to normal.

Hundreds who spent the night at emergency evacuation centres are staying on again tonight, afraid to return to houses with cracked ceilings and walls that creaked during the many aftershocks.

The 7.1 magnitude earthquake caused damage which could reach $2 billion to homes, buildings and infrastructure, and left thousands homeless. Authorities believe it could be weeks before all the damage was assessed and people were allowed back into their homes.

Many homes would never be lived in again and would be demolished because of the damage.

About 230 people spent the night at the three centres at Linwood College, Burnside High School and Addington Raceway but the Red Cross said they expected many more tonight.

Sarah McElroy, 19, fled to Addington Raceway after midnight, too rattled to stay at home.

She plans to take refuge in the solid concrete centre for days to come, sleeping on cushions in a large hall.

"They'll let us stay here until things settle. It's too frightening at home," Ms McElroy said.

Red Cross spokeswoman Rosemarie North said people needing emergency shelter should try to take stretchers and blankets to the centres if possible. They should also take medication and baby food.

"It would be helpful if they could bring their own bedding but they should definitely still turn up. We will find something for them," she said.

"Food is not a problem."

The priority was to offer people a safe and warm environment and a shoulder to learn on if they needed one. Counselling was available.

Yanni Tromp, who was running the Red Cross emergency centre at Linwood College, said today the trauma was reducing many people to tears.

She said yesterday in the first few hours after the earthquake people were dealing with the practicalities of getting food and shelter but today it was dawning on them they would have to find somewhere else to live if their homes were demolished or would takes weeks to repair.

"It is starting to sink in. We are starting to see more nervous and upset people than yesterday.

"Yesterday people took it more or less on the chin", but more were fighting off tears today, she said.

Many people were at the centre because their homes had no power, no water and no sewage.

Apart from the needs for food and shelter, many displaced people just needed a bit of a hug.

"Most of them will need a shoulder to lean on," said Ms Tromp.

Red Cross workers were heading to Christchurch from around the South Island and 2400 blankets were being sent from Auckland as priority cargo on a commercial flight.

"On the same flights we are going to get down 1950 4m by 6m tarps because so many houses have been damaged and are not weatherproof," Ms North said.

Civil Defence said rebuilding would still take weeks but already Christchurch Hospital is getting a stream of people with minor injuries from trying to fix their houses.

A man had fallen off trying to repair his roof when an aftershock hit, a spokeswoman said.

Kenneth McCaul, in Kaiapoi, said this morning he had a builder on his roof trying to securely cover holes before winds struck.

He had relocated from Perth in March into a newly-renovated two storey house. He had filled it with antiques - now it is filled with rubble, broken furniture and a chimney. Mr McCaul is fed-up.

"I want to get out of here. Perth sounds real good right now."