Just weeks before her 14th birthday, she had been walking to school at St Josephs when the fatal 7.8 magnitude earthquake struck.
"We were going into the school, and just as we got to it the school fell down," she said.
The quake had shocked her so much she ran home - leaving her seven siblings in her dust.
She married John O'Sullivan (who later dropped the O from his name), just before he returned overseas to serve in World War II.
Her late husband's picture and medals hang on the wall of the Hastings home she lives in with her son Francis, and his wife Zara.
Always a hard worker, Francis said his mother's age had not slowed her down. When he was growing up, his mother worked at a Hastings shop while his father shovelled coal in the freezing works.
"Mum would get us kids up and then she would bike to work, bike home at lunch to get Dad his lunch, bike back to work and then be home at 3pm for us when we came home from school," he said.
When she moved into her son's home 10 years ago, Zara would have to take the iron with her to work so Mrs O'Sullivan could not do anything but relax.
Although deaf, the 100-year-old is still remarkably healthy - she uses a walker as she has had trouble with her knees since she was 83, and surpassed all expectations after she was diagnosed at 97 with breast cancer.
When asked about her secret to longevity, the mother-of-two said she probably would not have made it to 100 without Francis and Zara.
"It's funny because she has loads of butter on her bread, she pours the salt on her food," Francis said. "The only thing she's never done is drink, or smoke".
"She's always looking after people, she's not worried about herself," Zara said. "She has Weet-Bix for breakfast every morning."
Mrs O'Sullivan said she had been proud to watch their family grow over the years - from their two children, four grandchildren, and one great-grand child with another on the way.
A big netball fan, one of her happiest memories was meeting former Silver Ferns captain Irene van Dyk.
She was also very fond of the Royal Family - and beamed yesterday as she opened her congratulatory card from the Queen.
"She's our queen", her granddaughter said.