Gai Chaney was holding her infant son in her arms when she was blown across the floorboards of her Darwin home on Christmas morning.

Key points: Cyclone Tracy made landfall in Darwin 45 years ago and was one of Australia's most significant natural disasters

Cyclone Tracy made landfall in Darwin 45 years ago and was one of Australia's most significant natural disasters Survivors have reported symptoms of PTSD decades after the event, with many struggling to cope over Christmas

Survivors have reported symptoms of PTSD decades after the event, with many struggling to cope over Christmas A tropical climatologist has said Darwin could be in the firing line for another devastating Category 4 or 5 storm

Forty-five years on, Ms Chaney said the pain of what followed — the tragic loss of her second-born child — haunts her to this day.

Survivors of Cyclone Tracy have said they are still experiencing ongoing trauma, and many have been diagnosed with post-traumatic stress disorder (PTSD) decades after one of Australia's worst natural disasters.

Tracy tore through the Top End during the early hours of Christmas morning in 1974, destroying at least 90 per cent of Darwin's houses and causing more than 30,000 people to flee the Northern Territory.

The ongoing impact on the people who have lived through such a devastating natural disaster has previously gone unrecognised and has been a "major issue", according to Cyclone Tracy survivor Robyn Cooper-Radke.

Ms Cooper-Radke was one of the founding admins of a Tracy survivors Facebook group, something she said had helped those suffering find solace.

Damaged houses lay ruined in Darwin after Cyclone Tracy struck. ( National Archives of Australia: AAP )

"It was created as a group where survivors could go and express their feelings and emotions in a safe and secure place," she said.

The private Facebook group has also become a place for those struggling in the lead-up to the 45th anniversary of the disaster, with many saying they hid from holiday festivities to avoid experiencing harrowing flashbacks.

Ms Cooper-Radke said the group had grown from a couple of hundred people to nearly 4,000 over the past several years.

"Unfortunately as the years go on, we are losing generations of people," Ms Cooper-Radke said.

"But this time of year it will pick up because people like to go on and share their struggles, emotionally and psychologically, with this time of the year — including myself."

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 1 minute 7 seconds 1 m 7 s A doctor at Darwin Hospital describes what it was like to survive Cyclone Tracy in 1974.

Survivors struggle over the Christmas holiday

Ms Cooper-Radke said she had been diagnosed with complex PTSD and shared a lot of symptoms with other survivors in the group.

"With the stigma of mental health being broken down, we are now seeing a lot more people in their 40s and 50s who did go through Tracy and they are being diagnosed with PTSD," she said.

"People could never understand, including myself, why we would struggle with Christmas when we got married and had young children.

"Hearing certain Christmas carols or even going into shopping centres can be enough to trigger some people. It's quite a massive issue."

"I am very frightened of loud noises, that's all reminiscent. Because that night the noise was phenomenal."

Ms Cooper-Radke said the longstanding impact of the event had been compounded by the dearth of psychological support following the disaster, especially for young children.

"We were on a little bit of a learning curve, I suppose, for Australians in natural disasters," she said.

A sign in Parap after Cyclone Tracy hit Darwin in 1974. ( Supplied: Robyn Cooper-Radke )

'It was like my heart was gone'

Ms Chaney spent the afternoon of Christmas Eve in 1974 wrapping presents for her young family.

As the sun rose over Darwin the next morning, her six-month-old son Paul was dead — one of 71 people killed when Tracy flattened Australia's most northern capital city.

"It was just devastation — I think every person thought that they were the only person left alive," Ms Chaney said.

The suburb of Alawa, where the Chaney family lived, on Christmas Day after Cyclone Tracy hit. ( Supplied: NT Archives )

As Tracy descended on Darwin and water started to flood through their house in Alawa, Ms Chaney and her husband Roger waded through their bedrooms and tried to create a makeshift shelter using mattresses.

"A wall caved in on us and I remember getting hit on the back of the head and sparks just seemed to come out of my eyes," she said.

"In seconds we were just getting blown across the floorboards and I had Paul, my baby, in my arms.

"Everything was disintegrating around us."

Gai and Roger Chaney lost their six-month-old son Paul in Cyclone Tracy 45 years ago. ( Supplied: Gai Chaney )

The family fled into their nearby car and tried to shelter through the night.

"I knew something had happened to Paul cause he didn't make a noise. He did not make a noise whatsoever," she said.

"It was like my heart was gone."

Ms Chaney said it was more than six months before the family found out where their baby was buried and it took five years for them to be able to afford to go back and visit his grave.

"We were left with $5 and the clothes from the Red Cross," she said.

'Absolutely soul destroying'

John Browne, who was living in Fannie Bay when Cyclone Tracy hit, said his family was still dealing with the trauma it inflicted.

"It was absolutely soul destroying," he said.

"One of my friends' father lost his life. A piece of roofing went through his chest and pinned him to the ground.

"To hear some of the stories was absolutely terrifying. We are still traumatised by it.

Houses destroyed by Cyclone Tracy on Christmas Day 1974. ( Supplied: Baz Ledwidge )

"We went back to Darwin and we went to the museum there, and they have this room. We went in there and my daughter broke down."

Ms Chaney also said her family had struggled with PTSD caused by the cyclone.

"I don't like it when it gets very windy, I hate it," she said.

"I don't even have to close my eyes; I can see everything and hear everything.

"But I have been lucky enough, people have listened to me and I have been able to talk about it and I think that has helped.

"I think a lot of people have learnt from Tracy and are getting support. We never got any counselling whatsoever, ever."

The Facebook group's administrators and group members are now pushing for a memorial to be constructed in the Darwin CBD to remember those who died and those who lived on with loss and trauma.

One of Darwin's main streets the morning after Cyclone Tracy. ( Supplied: Baz Ledwidge )

Could it happen again?

Bureau of Meteorology tropical climatologist Greg Browning said there was a number of reasons why Tracy was so destructive.

"First of all it was a direct hit on Darwin," he said.

"It happened on Christmas Eve at a time when I'm sure people were otherwise occupied.

"And it was a very strong storm. Even though the equipment at Darwin Airport broke at its peak, it recorded gusts well in excess of 200kph and there is a chance it could have been even stronger."

Mr Browning said the technology used to forecast cyclones had improved "leaps and bounds" since Tracy.

"It was the dark ages back then compared to what it is now," he said.

A house in Casuarina in the days following Cyclone Tracy. ( Supplied: NT Archives )

Will cyclones get worse in the future?

But advancements aside, Mr Browning said Darwin could still be in the firing line for another Category 4 or 5 storm.

"They have, in the past, happened every 30 to 40 years, so in some sense you could say maybe there is one not too far away, but by the same token it is all very fickle," he said.

"Unfortunately I don't think the science will ever be good enough to say 'OK this year we're definitely not going to get something that happens like Tracy'."

Mr Browning said there was also a lot of conjecture as to how tropical cyclones would behave as the world warmed from climate change.

Territory resident Chris Adams stands amid the destruction of Cyclone Tracy on Boxing Day 1974. ( Supplied: NT Archives )

"At this stage most of the climate projections we have suggest we may actually see a decrease in the overall number of cyclones," he said.

"However, it looks like while they may not be as frequent as they have been in the past, when they do form they will potentially be stronger.

As another Christmas comes around, those who lost everything during Tracy have urged people to remember that the holidays can be a hard time for those affected by natural disasters.

"I think there are a lot of people out there that need some support, even now. I know a few people still living in Darwin and they can't talk about it," Ms Chaney said.