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LIST OF TABLESTable 2.1 Landslide Movement Types .................................................................................................. 4Table 3.1 Landslide Events per County .............................................................................................. 14Table 3.2 Landslide Events – Materials ............................................................................................. 14Table 3.3 Landslide Events per Century ............................................................................................. 15Table 3.4 Bedrock Types in the Pollatomish Area .............................................................................. 17Table 5.1 Digital datasets of relevance to landslide hazard assessment ............................................ 37Table 5.2 Digital Sensor Data of relevance to landslide hazard assessment ...................................... 38Table 5.3 Datasets available for Co. Mayo case study ....................................................................... 39Table 5.4 Relative percentages of particular subsoil categories and their associated mappedNSS soil classes ............................................................................................................... 40Table 5.5 Area and number of events identified in each block ............................................................ 49Table 5.6 Landslide Classification (Northmore, 1996) modified ........................................................... 52Table 5.7 Number and type of landslides mapped .............................................................................. 53Table 5.8a Maximum and minimum weights and class affected for Bedrock slides .............................. 63Table 5.8b Maximum and minimum weights and class affected for Peat slides ................................... 63Table 5.8c Maximum and minimum weights and class affected for Flows ............................................ 63Table 5.8d Maximum and minimum weights and class affected for Falls ............................................. 63Table 5.9a Equal interval and manual method divisions applied to Bedrock slides ............................... 64Table 5.9b Equal interval and manual method divisions applied to Peat slides ..................................... 64Table 5.9c Equal interval and manual method divisions applied to Flows ............................................. 64Table 5.9d Equal interval and manual method divisions applied to Falls ............................................... 64Table 5.10 Percentage of events mapped contained within each susceptibility category ...................... 58Table 8.1 Participants in Landslides Workshop. TCD 2004 ................................................................ 80Table 8.2 Table of Researchers.......................................................................................................... 81LIST OF PLATESPlate 1.1 La Conchita, California 1995, 2005 (http://landslides.usgs.gov/) ........................................... 1Plate 1.2 Pollatomish Landslide .......................................................................................................... 2Plate 3.1 Pollatomish Landslide ........................................................................................................ 19Plate 3.2 Derrybrien Landslide .......................................................................................................... 21Plate 4.1 Herringbone drainage system being installed in cut slope of glacial till ............................... 26Plate 4.2 Slope failure in a glaciolacustrine deposit ........................................................................... 27Plate 4.3 Slide on the Grand Canal near Edenderry (Pigott et al., 1992) ............................................ 28Plate 4.4 Potential toppling failure at Monesk townland on the Cavan/ Leitrim border,also known as Englishman’s Mountain (Photo – Xavier Pellicer, GSI) ................................. 31Plate 5.1 Rotational landslide and subsequent rock falls occurring in Cuilcagh Mountains,County Leitrim. ................................................................................................................... 47Plate 6.1 Damaged House at Pollatomish ......................................................................................... 66Plate 7.1 Rotational Landslide (Basalt over Chalk) at Garron Point, Coast Road, Co. Antrim ............. 74Plate 7.2 Mudflow at Minnis North, Co. Antrim .................................................................................. 74
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
Page 1 and 2: Landslides in IrelandGeological Sur
Page 3 and 4: LANDSLIDESinIRELANDEditorRonnie Cre
Page 5 and 6: CONTENTSPreface ...................
Page 7: Fig. 4.3 Forces caused by water in
Page 11 and 12: een very important in populating th
Page 13 and 14: involves a report on the current st
Page 15 and 16: Main Objectives• Increase public/
Page 17 and 18: 1. INTRODUCTIONRonnie Creighton1.1
Page 19: 1.3 The Landslides PublicationThis
Page 22 and 23: Peat flows are not nearly so well d
Page 24 and 25: In Ireland the Quaternary or uncons
Page 26 and 27: Journal - published papersLetter -
Page 28 and 29: Fig. 3.1 Two images showing the use
Page 30 and 31: Table 3.1 Landslide Events Per Coun
Page 32 and 33: Fig. 3.3 Location map of the Pollat
Page 34 and 35: 3.7.4 Quaternary GeologyQuaternary
Page 36 and 37: 3.8 The Derrybrien Landslide - 2003
Page 38 and 39: • The classification scheme shoul
Page 40 and 41: The force causing the block to slid
Page 42 and 43: Plate 4.1 Herringbone drainage syst
Page 44 and 45: 1210Number of events864Raised bogBl
Page 46 and 47: It is well known by research at Uni
Page 48 and 49: 5. LANDSLIDE SUSCEPTIBILITY MAPPING
Page 50 and 51: Two simplified hypothetical example
Page 52 and 53: 5.1.4 Mapping and GISBy definition,
Page 54 and 55: Platform / sensor pixel resolution(
Page 56 and 57: For this initial run, the criteria
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42Fig. 5.5 Peat and peaty podzols f
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for susceptibility mapping purposes
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elationships between developed susc
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The methodology used to derive the
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50Fig. 5.12. Landslide susceptibili
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52Table 5.6. Landslide classificati
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The percentage of events occurring
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with slope, overall 20-25% of all e
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As the dataset was not available at
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CHAPTER 5.2 - TABLE APPENDIXBedrock
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6. LANDSLIDES AND PLANNINGAileen Do
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6.2.4 Development ManagementThe phy
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6.5 Current Practice on Landslides
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7. LANDSLIDES IN NORTHERN IRELANDTe
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2. MudflowsPlate 7.1 Rotational Lan
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7.2 Carboniferous Cliff Lines (Co F
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8. RESEARCH ON IRISH LANDSLIDESKoen
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8.4 Research. Post-2003 AbstractsTa
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Identifying, recognizing, and predi
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In the case of vulnerability mappin
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Steep slopes in glacial tillMichael
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9. RECOMMENDATIONS FOR FUTURE WORK9
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Priority 1 Peat slides and peat str
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TEXT REFERENCESAcreman, M., 1991. T
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Skipper, J., Follett, B., Menkiti,
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APPENDIX 2Glossary of TermsBlanket
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APPENDIX 3Nomenclature for Landslid
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APPENDIX 4101
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103
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Hammond, R. 1979. The Peatlands of
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APPENDIX 7Useful Web Linkswww.gsi.i
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