PORTLANDERS feared they had been hit by an earthquake when their homes swayed and furniture moved as tremors hit the island.

People living in Fortuneswell say they felt a surge through their houses and the chairs they sat on moved across the floor.

It was later discovered the strong vibrations were aftershocks from a huge blast at nearby Admiralty Quarry.

Quarry owners G Crook and Sons said the controlled explosions cleared between 10,000 and 15,000 tons of stone from the rockface.

Margaret Dunlop, of Fortuneswell, said: "It really shook the house, which was built in 1710 and the walls are very thick.

"I'm used to lorries coming along our road but this felt like an earthquake. We were very worried. My son was upstairs and he felt the house swaying and I saw the whole table move. It was very unsafe."

Her neighbour Norman King, 68, said: "I was sitting in the front room with my wife watching television when all of a sudden it happened. There was no audible sound of an explosion but a tremor came through the house in a horizontal plane.

"It made the settee we were sitting on vibrate backwards and forwards. I thought: 'What the heck is this?'

"We have a three-storey semi-detached house and it makes you wonder what that is doing to the foundations."

Mr King added this was the strongest in a series of tremors he had experienced at his home in recent months.

G Crook and Son contracts manager Roger Ferris confirmed this was the sixth controlled explosion carried out at Admiralty Quarry over the last six months.

He added that the blast was in line with environmental regulations and monitors were placed at Tillycombe and near the Young Offender Institution to measure its strength.

The results are due to be released later today.

Mr Ferris said: "We called in a specialised company to carry out the blast to clean up the rockface. It was done under proper supervision, the council was notified and the environmental code of practice has been adhered to.

"This blast was no different to the other ones we have done. It could feel stronger because the strata or faults running through the rock may have carried the vibrations along."

He added there are no plans for further blasts 'in the near future'.

A seismologist at the British Geological Survey said the tremors were not caused by an earthquake or any other natural event.