The dangers of landslides in Ireland have been grossly underestimated and urgent action is needed to safeguard communities, a new report has warned.
The report by Geological Survey of Ireland (GSI) sets out recommendations for the integration of landslide hazard issues into the planning process.
The GSI in early 2004 established the Irish Landslides Working Group a year after landslides near Pollatomish, in Co Mayo, and in Derrybrien, Co Galway.
The Mayo event was preceded by periods of exceptionally heavy rainfall which were thought to have triggered ground failure.
At the Derrybrien site, construction work for a wind farm was thought to have been a further contributory factor, the report stated.
Dr Peadar McArdle, director, GSI, said: "An important conclusion of the work to date is that the incidence of landslide events in upland areas in Ireland has been grossly underestimated."
The initial search of reference sources in the historic database had identified 117 events. However, a pilot survey carried out by GSI in the Breifne uplands covering parts of Sligo, Cavan and Leitrim in 2005 recorded over 700 historic events over a "county size" area.
Dr McArdle said this pointed to the fact that nationwide there were probably many thousands of unrecorded landslide events.
Many more events would be identified in future research. The preliminary analysis indicated that Co Wicklow had the most events at 14, Co Mayo 12, Co Antrim 10. The majority of events, 63, involved peat as the main material while some 31 were composed of coarse debris.
"There is an urgent need to document these events as the first step in delineating landslide-prone areas, and in order to produce landslide susceptibility maps to better inform planning decisions to mitigate future property loss and safeguard our communities," Dr McArdle said.
A better understanding of these events and how they occurred through focused and applied research programmes was also needed, he added.
"The focus must be on the expansion of the national database with a systematic survey of the country, targeted geotechnical research, the preparation of landslide susceptibility maps and the integration of landslide issues into the planning process," Dr McArdle said.
Expanded development, with increased population pressure, new housing construction coupled with expanded infrastructure and communications systems, would inevitably encroach into potentially hazardous areas, Dr McArdle warned.
Predictions of accelerated climate change may further exacerbate property loss and environmental degradation resulting from more frequent landslide events.
"We must act now to curb the cost of future landslide hazards through better understanding and mapping of these hazards and by improving our capability to mitigate and manage such natural disasters," he said.