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Landslides Workshop 2009
The Geological Survey of Ireland is holding a day long Workshop on Landslides in Ireland on Tuesday 21 April 2009 in the GSI office in Dublin. Subsequent to the publication of the “Landslides in Ireland” Report in August, 2006, the GSI, in June 2008, began a major multi-annual project on Landslides Susceptibility Mapping in Ireland. This project was a major recommendation of the Landslides in Ireland Report 2006. The aim of the Workshop is to introduce a wide range of stakeholders to this project and to consider landslide geohazard issues in Ireland today. The Workshop will contain a series of presentations covering a wide range of topics including susceptibility, geotechnical engineering, landslides and the planning process, remote sensing and GIS, and case studies.
Landslides are a major cause of substantial damage to property and loss of life every year across the globe. They are a major geohazard and can be triggered by earthquakes, volcanic eruptions, heavy rainfall, or indeed by man-made activities. Ireland is not a high risk area for major landslide events and in fact is a relatively benign environment in this regard compared to other countries. However the historic record does contain a few serious events such as that at Castlegarde in Co. Limerick when twenty-one people died. The events at Pollatomish and Derrybrien in 2003 brought this issue to the fore, and it was clear that there was no collated body of data either on the historic record or the susceptibility of areas to landslides in the future. GSI in response to the 2003 events, visited and wrote a brief report on the Mayo events and began a wider study of landslide occurrence in Ireland.
These events are potential hazards to life and property, and while no one was killed recently, more than 34 people have lost their lives in such events in Ireland. The recent landslides would seem to be the result of a long dry summer causing drying out and weakening of unconsolidated sediments including peat or subsoil. Heavy rains can then saturate the peat, via the fractures or weaknesses caused by the drying, and this can allow slides to develop, shifting unstable surface deposits to lower ground. These situations are not landslides involving fracturing of the bedrock beneath the subsoils, but are largely unconsolidated material moving on an impermeable horizon, which is usually at or near the bedrock surface. The most common feature of all these landslide events is that they are usually related to periods of heavy rain which can both destabilise sediments and 'lubricate' such earth movements.
In the fine book on The Bogs of Ireland by John Feehan and Grace O'Donovan, published by UCD Environmental Institute in 1996, there is a very interesting section which documents over 40 bog bursts recorded in the last hundred years or so. These are located around the country and no area is immune, though they do of course mainly occur in the West, where the bogs are most common. Further references to Irish Landslides and Bogbursts can be viewed by clicking here.
Some images of Landslides can be viewed in the Gallery
In early 2004 the Geological Survey of Ireland (GSI) established a multi-disciplinary team, the Irish Landslides Working Group (ILWG), with expertise in geology, geomorphology, geotechnical engineering, planning, and GIS.
The main objectives were:-
1. Build a national database of past landslide events.
2. Examine geotechnical parameters with regard to landslides.
3. Assess the potential for landslide susceptibility mapping in Ireland.
4. Make recommendations on the integration of landslide hazard issues to the planning process.
5. Promote landslide research in Ireland.
6. Raise public awareness about landslide hazard in Ireland.
GSI has done some work recently on Landslides Susceptibility Mapping.
A related project, in which GSI are involved with the European Space Agency is looking at subsidence mapping and called TerraFirma.
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