THE strongest earthquake detected off the west coast since records began rattled windows, shook houses and caused chimneys to crack yesterday.
The magnitude-four tremor, which struck 60km west of Co Mayo shortly before 9am yesterday, was the strongest in Britain or Ireland for around two years, according to the British Geological Survey.
Tom Blake, director with the School of Cosmic Physics at the Dublin Institute for Advanced Studies, said this was a "very important seismic event" as it was the first quake reported in that area since records began in 1978.
Deep rumbling sounds -- similar to an oncoming train -- and buildings shaking were reported in a number of areas in the counties of Mayo and Sligo.
Phil O'Hara, who lives with her husband, John, in the townland of Killure, Aclare, near the Sligo/Mayo border, discovered a chunk of masonry had fallen from her chimney.
"I was walking down the hallway just before 9am when I heard the bang. It was like a drum or a rap of thunder," Ms O'Hara, who was among dozens to feel the tremor, said.
"After breakfast I found a three-pound lump of concrete on the ground when I went out to hang some clothes on the line. It had fallen from the chimney. I was quite frightened."
Brian McConnell of the Geological Survey of Ireland confirmed there had been no quake off Co Mayo since records began. He said there was a known faultline in these areas, so there was a firm "geological reason" for the quake.
The area where it occurred is in the middle of a plate that is moving further from America, hence the force was not on the scale of areas where plates collide such as California or Japan.
Mr McConnell ruled out the possibility of the tremor having anything to do with oil and gas exploration activity off the western seaboard.
British Geological Survey seismologist David Galloway said it was "not a warning of anything bigger to come" and described it as only significant as the region does not receive big earthquakes such as those that hit Italy or Turkey.
Energy Minister Pat Rabbitte said there was "no link" to activities in the Corrib gas field.