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Landslide & Slope
Instability Geohazards: Classification Schemes - EPOCH |
EPOCH. 1993. The temporal
occurrence and forecasting of
landslides in the European community (Ed:
Flageollet, J. C.). Contract No. 90 0025, 3 Volumes.
Movement Type |
Rock |
Debris |
Soil |
Fall |
Rock
Fall |
Debris
Fall |
Soil Fall |
Topple |
Rock
Topple |
Debris
Topple |
Soil Topple |
Slide (Rotational)
|
single (slump) multiple
successive |
single multiple
successive |
single
multiple
successive |
Slide (Translational)
Non - rotational
|
Block
Slide |
Block
Slide |
Slab Slide |
Planar |
Rock Slide |
Debris Slide |
Mud Slide |
Lateral Spreading |
Rock
Spreading |
Debris
Spread |
Soil (Debris) Spreading |
Flow |
Rock Flow
(Sackung) |
Debris Flow |
Soil Flow |
Complex (with run-out or change of behaviour
downslope; note that nearly all forms develop complex behaviour) |
e.g. Rock avalanche |
e.g. Flow Slide |
e.g. Slump - earthflow |
Note: A compound landslide is one that
consist of more than one type e.g.. a rotational - translational
slide. This should be distinguished from a complex slide where
one form of failure develops into a second form of movement,
i.e.. a change of behaviour downslope by the same material. |
The European classification, developed
by the EPOCH (1991-1993) project (The Temporal Occurrence and Forecasting of
Landslides in the European Community, Contract no. 90 0025) is simple and
suitable for European conditions. The mechanism of failure underlies this
scheme. The classification uses the terms fall, topple, slide (rotational),
slide (translational), lateral spreading, flow and complex.
A fall usually denotes the free fall movement
of material from a steep slope or cliff, whereas a topple, which is similar to a
fall in many respects, normally involves a pivoting action rather than a
complete separation at the base of the failure. Movements occurring on a
distinct slide or shear surface are termed slides. These may be subdivided into
rotational and translational according to the form of the failure surface.
Rotational slides involve a semi-circular shear surface, whilst translational
failures usually occur ob planar slip surfaces. Lateral spreading is
characterised by the low angled slopes involved and the unusual form and rates
of movement. Flows normally behave as a fluidised mass in which water and
air are significantly involved. The complex failures are principally a
combination of two or more of these described movements. (Dikau et al, 1996)
|