More landslides could occur in mountainous peat areas if there is heavy rainfall, according to an NUI Galway geologist.
Such movements can be significant, and are usually associated with prolonged wet weather, Prof Mike Williams, of NUI Galway's geology department, said yesterday. However, they can also be triggered by a prolonged dry spell, such as that which has occurred over the past few months, which can cause the peat to perish.
"As the peat dies and shrinks, many little root systems attached to the bedrock also die", Prof Williams explained. "With nothing holding it, it doesn't need anything to set a movement off. It could be the one last little root dying which causes a major shift."
Records examined by Prof Williams show that there were four major landslides in Co Galway alone during the period 1740 to 1890, with one in Dunmore, north Galway, lasting 11 days in 1873.
A bog slide in Co Kerry in 1896 killed a family of six, all of whom were found naked in the slurry as they had been asleep at the time.
On June 26th, 1821, a bog began to slide near Clara, Co Offaly, and moved at a rate of two yards an hour. It continued moving for more than a month before it stopped.
"Sometimes the movements can be very rapid, on other occasions it can resemble a lava flow.
"When it starts raining in the next few weeks, it could be a very dangerous time given the summer that we have had."
Environmentalists have expressed concern that overgrazing is also increasing the risk of landslides.
The Derrybrien landslide began just a month after the landslide at Pollathomas in Co Mayo, which forced over 40 families to leave their homes and destroyed Pollathomas graveyard. The landslide occurred less than two miles from Bellanaboy, site for the Corrib gas terminal, and began during a period of heavy rain.
Eight families still cannot return to their homes, and there are a further four unoccupied homes in a zone designated as high risk by Mayo County Council. The cost of the damage has been estimated at €3 million.
