to download report - Geological Survey of Ireland

In the case of vulnerability mapping, geology (source: GSI), soil type (source: Teagasc) slope (source: OSI)and average rainfall (Met Eireann) maps were combined. It is hoped to ascribe values to each factor based onsusceptibility allowing for the creation of a slope stability/vulnerability map to be created. This map can then betested against known locations of landslides, for example the Pollatomish landslides.Fig. 8.6 Locations of known landslides in Ireland which have been subdivided by type of slide.Submarine slope failure morphology offshore IrelandGavin ElliotThe Irish offshore region is nearly 10 times the area of the Irish mainland. However up until the last 30 yearsvery little systematic work had been undertaken there, particularly the Atlantic margin (Fig. 8.5). Over the last20 years researchers at the Department of Geology at UCD together with DIAS and other institutes, have beeninvolved in attempting to unravel the mysteries of the Atlantic margin from deep crustal studies to seabedsurface morphology.The seabed morphology was poorly constrained until two extensive sidescan sonar surveys were undertakenin 1996 and 1998 respectively. These surveys imaged the numerous submarine canyons that incise the margin100 km west of Ireland. Integration of the sidescan sonar data with the existing seismic reflection data andbathymetry data revealed that the canyons could be up to 400m deep, in excess of 40 km long and in one caseenclosed in between 30° walls. The sidescan sonar also imaged (with resolution down to 5m) numerousheadwall scarps of submarine landslides. Only headwall scarps can be imaged as the main body of the failurehas been transported as debris flows into the deep basin and can be found on the basin floor.85