Trench DocsRisk Classification for Slope Instability
The classes of risk adopted in Trench are:
| Risk Class | Generalised Field Evidence |
|---|---|
| Very low | Flat or sloping land, with thin soils on 'hard' or weathered 'hard' rocks. Risk may increase with increasing slope or soil depth. |
| Low | Flat land or land on slopes generally less than 7 degrees, on 'soft' rocks or deep soils on 'hard' rocks, with no evidence of active or recent slope instability. May include areas of fossil instability. |
| Medium | Land generally steeper than about 7 to 10 degrees on 'soft rocks or deep soil on 'hard' rocks, with no evidence of active or recent slope instability. May include areas of fossil instability. |
| High - Very high | On slopes of any angle with evidence of active or recent landslips, or rockface instability. May include areas of fossil instability. |
Definitions
Fossil: Not likely to have moved during or since European occupation.
Recent: Likely to have moved during European occupation.
Active: Moving now, or has moved within the last decade or so.