Ireland was hit by a mini-earthquake yesterday and there may be more tremors to come.

The quake, measuring 2.2 on the Richter scale, rocked an area of 30 square kilometres between Letterkenny and Buncrana in Donegal shortly after 1am.

Scores of people reported a loud rumbling noise lasting up to nine seconds. However, the tremor was too small to cause any damage.

"The last time this happened two years ago there were three of them within a few weeks of each other," said Brendan O'Donoghue, a physics teacher at St Columba's College in Stranorlar. His pupils were yesterday studying readings taken on the school seismometer.

"The earthquake hit Co Donegal around three minutes before 1am, peaking at 30 seconds past the hour. It's slightly bigger than the last quake in the same area two years ago which was 1.9 on the Richter scale," Mr O'Donoghue said.

"It has certainly caused quite a stir in the school and gives the students here renewed interest in geology."

There were no reports of any damage with the epicentre pinpointed between Rathmullan and Portsalon on the Fanad peninsula.

"It was a deafening noise and the house definitely shook," said Mary McGinley (33) from Letterkenny. "I thought at first it was thunder and then I looked outside and at that time it was a calm night with a clear sky."

Donegal sits on the Lennan faultline which runs on through Scotland and on to Norway.

David Galloway, from the British Geological Survey which picked up the earthquake, said it was "quite a moderate quake for Ireland".

He said it happened around 3km beneath the earth's surface and said while it was not possible to definitively say whether or not there would be more, he added: "There is a possibility of aftershocks, especially with the history of earthquakes in Donegal in recent years."

Dr Tom Blake of the Irish National Seismic Network wants to contact anyone who witnessed the quake.

"Anything above 2.0 on the Richter Scale could be regarded as a minor earthquake. We have had reports about the tremor and we would like to hear from people first-hand experiences of the tremor," he said.