Cracked tile mystery deepens

The tiles at the Far North GAS station (centre of left aisle) popped up and were damaged when the Seddon earthquake hit.

Mystery surrounds the cracking of tiles on the floor of a Far North service station.

Owner of GAS service station at Coopers Beach, Simon Allan, was yesterday ripping up the tiles in search of answers after a section of the tiles popped and then cracked about 5.23pm on Sunday.

At the same time a 4.3 magnitude quake, 20km south of Seddon in the South Island, was measured.

GAS worker Gavin Wilde said he had been behind the counter when he noticed the floor by some shelves had a bubble in it and a few tiles had lifted.

"At first I thought I was seeing things. Then a heap of them started popping, that's when I rang the boss," Mr Wilde said. "Then I could hear more popping. It was pretty freaky."

He had rushed outside to turn off the water mains but later discovered there was no piping under the shop floor.

A GeoNet seismologist in Wellington said he was not convinced the Northland incident was related to the big jolt felt hundreds of kilometres south.

However, Mr Allan is adamant it was no coincidence.

"Tremors were felt in Dargaville and that's not too far away from us," he said.

Mr Allan said he had pulled up the tiles to see if there were any cracks in the concrete that could provide some answers.

Maungatapere tiler Craig Horan, with nearly two decades in the tile business, said it was unusual for tiles to crack as they had.

He said over time hairline fractures could develop and if grouting worked loose the tiles could crack.

He said it sounded as if there had been some pressure from below the tiles or the concrete block underneath had moved.