Isobel was 14-and-a-half when the Napier earthquake hit. Decades later, her grand-daughter interviewed her about it for a school project.

It was the morning of 3 February, 1931.

My Nana, Isobel, was 14-and-a-half years old. Her family lived at Whakatu, not far from Hastings.

It had been a hot, dry summer and it was her first day back at Mangateretere School.

Everyone was outside on the field because they weren't doing any work - it was just too hot.

But at 10.47am, disaster struck.

"I've never forgotten that day ."

"It just felt as though someone had punched me right in the small of the back. I was looking around to see who had done it and I nearly had a fit when I saw the ground up there."

Isobel and her schoolmates were knocked right off their feet.

The shaking went on for about 45 seconds, she said.

Others who felt the magnitude 7.8 quake reckoned it went on for more than two-and-a-half minutes.

The Napier earthquake remains New Zealand's deadliest natural disaster - 256 people were killed.

Across Hawke's Bay, the ground shook, cracked and rolled.

Huge expanses of land were pushed up out of the sea.

Napier and Hastings were in ruins - buildings crumpled and the streets were covered with debris.

In 1998, when I was almost 10, I interviewed Nana about what she saw that day - I was doing a school project about the disaster.

When it hit, she said it sounded like thunder.

Was it scary? I asked.

"It was scary alright because we didn't realise what was going on."

There was a lot of damage inside the school, things falling off walls and books coming off shelves.

"We saw the chimney at the Whakatu freezing works go, it was a brick one of course, and it just seemed to shoot off in the air and break in three bits and fall and there was an awful lot of dust that went up after it," she said.

Nana's brother picked her up from school and took her home.

Her mother was inside the house when the earthquake hit and rushed outside.

"She got to the backdoor and there was a big safe hanging there and it came and hit her," Nana said.

"She was thrown down to the bottom of the back steps - and they were quite high and of course there was a concrete floor."

Luckily, she ended up with just a few bumps and bruises.

But the house was a mess, Nana said.

"The wardrobe with the mirror on the door fell over. Dad went and picked it up and then it fell down again that night.

"The cupboard doors flew open and all the jam on the shelves dropped on the floor."…

Go to this episode on rnz.co.nz for more details