to download report - Geological Survey of Ireland

PREFACEUntil recently Ireland has been regarded as a comparatively benign environment as far as landslides areconcerned. However, two widely publicized landslides in the autumn of 2003 that occurred near Pollatomish inCo. Mayo and Derrybrien in Co. Galway demonstrated the extent of property damage and social upheaval thatcan result from such events. The Mayo event was preceded by periods of heavy rainfall which are thought tohave triggered ground failure; at Derrybrien site construction work for a windfarm is thought to have been afurther contributory factor. Fortunately on this occasion there was no loss of life or serious injury, althoughhistoric events have done so, such as that at Castlegarde, Co. Limerick in 1708 which claimed 21 lives.The events of late 2003 served to emphasize our paucity of knowledge and understanding of such landslidesand bogslides in Ireland. To address this situation, GSI in early 2004 established the Irish Landslides WorkingGroup with membership invited from other Government Departments, state agencies and the university sector.Those who volunteered to join the Group brought with them a wide range of expertise in geology (both bedrockand glacial deposits), geomorphology, geotechnical engineering, planning and GIS. Since its inception theIrish Landslides Working Group has worked well and in a focused manner to deliver this report of their deliberationsand data gathering.An important conclusion of the work to date is that the incidence of landslide events in upland areas in Irelandhas been grossly underestimated. The Irish Landslides Database which has been created records just over100 entries historic landslide events whereas in Britain the British Geological Survey inventory records over10,000 events. A pilot survey carried out by GSI in the Breifne uplands, in the north-west of Ireland in 2005recorded over 700 historic events over a “county size” area, pointing to the fact that nationwide there areprobably many thousands of unrecorded events. There is an urgent need to document these events as the firststep in delineating landslide-prone areas and in order to produce landslide susceptibility maps to better informplanning decisions, to mitigate future property loss and safeguard our communities. Equally we need to betterunderstand these events and how they occur, through focused and applied research programmes.As development expands in Ireland with increased population pressure, new housing construction coupled withexpanded infrastructure and communications systems will be required that will inevitably encroach into potentiallyhazardous areas. Predictions of accelerated climate change may further exacerbate property loss andenvironmental degradation resulting from more frequent landslide events. We must act now to curb the cost offuture landslide hazards through better understanding and mapping of these hazards and by improving ourcapability to mitigate and manage such natural disasters.Dr. Peadar McArdleDirectorGeological Survey of Irelandi