High Resolution 1:10,000 scale Mapping Strategy of Multi ... - NDMA

the basis of the relationship between the unstable mass and the failure surface and
the internal structure and deformation of the mass.
(A) Falls- The material may be in freefall, losing contact with the failure surface
intermittently or entirely. In this type of landslide the mass moves as individual
particles, with no coherent structure developing between particles.
(B) Slides- Move as coherent blocks or masses along the failure plane. Slides
exhibit little internal shear or deformation such that patches of turf, trees, and
structures on the surface may stay relatively intact and are not incorporated into the
slide. Soil or sediment stratigraphy within the sliding mass also may be preserved.
(C ) Flows- Move as a coherent but constantly changing mass, involving internal
shear or mixing of the mass,even sorting based on particle size and position in the
flow. Surface features such as turf, shrubs, trees, and structures are incorporated
into the flow. Downslope materials and surface features may be buried by the flow
mass, but they may also be incorporated into the flow as this type of slide tends to be
erosive as it travels along its path.
SLOPE MODELING
The forces acting on a point along the potential failure plane are illustrated in Figure
App 5.1. All variables in the figures, equations, and tables are defined in Table App
5.1.
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