"It's going to be re-traumatising them, they're going to re-experience something they haven't experienced for a long time," she said.
"We can expect those people to have a harder time in recovering from this event than other people."
Rucklidge said this earthquake didn't have the intensity and ferocity of the earlier quakes that struck the city.
"Physically things are going to be okay here, so it's going to be the emotional side," she said.
Three evacuation centres have been opened in Christchurch at Linwood College, Mairehau School and Akaroa School Hall.
Rucklidge said how children respond was often dependent on how their parents coped.
"If you have an already anxious parent, then that could very easily feed off on to the child," she said.
Her advise was to get kids back into routine as soon as possible and not over react about the event.
"Just say 'yup, we've just had an earthquake but we're okay, and we know what to do and we know how to respond," Rucklidge added.
Christchurch grandmother Angie Chee stayed in bed as the 7.5 magnitude earthquake rocked her Middleton home.
Instead of feeling anxious Chee said she felt tired of earthquakes hitting the city.
"I was thinking 'oh no, not again' and about the hassle of having to go through the repairs again," Chee said.
"We were a bit naughty, in fact we just remained in bed thinking whether to get up or not, and we didn't.
"I'm just so used and quite numb to earthquakes now, but this one really rolled on for quite a long time."
Except for 4-year-old Anzac Ta-ala, her three other grandchildren aged between 15 months and nine slept through the quake.
Mark Ong, who called the Herald from Singapore, said he was worried that his daughter, Myra, was "stranded" in Kaikoura.
The 21-year-old was on her second day touring the South Island after completing a student exchange programme at AUT University.
"She wants to get out of there but she's told us that it's impossible to get to the airport for a flight to Auckland," Ong said.
"All we know is that she and the group are seeking shelter somewhere near the hospital."
In North Canterbury, power was cut from Kaikoura to Cheviot and slips and damages to the bridge had isolated Rotherham and Waiau.
Now is the time to look after each other as the Hanmer earthquakes affect different people in different ways.
Public Health Specialist Dr Lucy D'Aeth, Chair of the Greater Christchurch Psychosocial Committee urged people to look after themselves and each other.
"For the most affected communities, the priorities are the most basic things - sharing clean water, food, and checking in on neighbours," she said.
"There will be those who need support to dig a long-drop/outside toilet, or tidy up damaged properties."
D'Aeth said it was normal to feel a range of emotions, so expect people to be coping differently.
"Our brains react chemically to earthquakes - releasing adrenaline which can cause us to feel shaky, queasy or on-edge and make it hard for us to concentrate. This response is our body's alarm system - it is your body telling you to be alert and ready for action," she said.
"These emotions should calm - but they can take longer to do so if the aftershocks continue for some time."
D'Aeth also said keeping normal routine will help, especially when around children.Additional staff have been rostered on to the Canterbury Support Line.
The free 24-hour phone line 0800 777 846 can help arrange appropriate support for those affected by the earthquake.
