Landslide susceptibility
GSI's national landslide susceptibility map rates how likely the ground is to fail, based on slope, the type of ground (peat and some subsoils are more prone) and the record of past landslides. The classes are:
- Low and Moderately Low: most lowland sites.
- Moderately High: steeper slopes or weaker ground; worth an engineer's look before building.
- High: the most susceptible ground, typically steep upland slopes and peat.
- Made ground: artificial fill, flagged separately because its behaviour depends on how it was placed.
Some areas are marked "(inferred)", meaning the class was interpolated from surrounding data rather than mapped on the spot.
Peat slides are Ireland's most damaging type, and are often set off by heavy rain or by works on the slope itself: drainage, excavation, roads or forestry.
Karst features
Karst forms where water dissolves limestone. GSI's karst database records:
- Swallow holes: where streams or surface water disappear underground.
- Enclosed depressions and caves.
- Springs: where underground water comes back out.
- Turloughs: seasonal lakes that fill from groundwater in winter.
Why they matter: water and pollution reach the groundwater very quickly through karst, so septic tanks and run-off near a swallow hole get extra scrutiny. Turloughs and karst depressions can also flood, from below.
What it can't tell you
- Susceptibility isn't a prediction that a slope will fail. It's a national screening map at 1:50,000.
- The karst database records what has been found and reported. Many features, especially small ones, aren't in it.
- Karst features are listed in the report but not drawn on the map: GSI's service doesn't return their map positions.
Sources
- Geological Survey Ireland: Landslide Susceptibility Classification 1:50,000; Karst Features database, gsi.ie
Last reviewed 2026-10-02.