Civil Engineering Reference
In-Depth Information
TABLE 9.2
Earthquake-Induced Slope Movement in Soil
Main type
Minimum
of slope
Material
slope
Threshold
Relative
movement
Subdivisions
type
inclination
values
abundance
Falls
Soil falls
Granular soils
40
(1.2 : 1)
M
L
4.0
Moderately
that are slightly
common (1000 to
cemented or
10,000 in the 40
contain clay
earthquakes)
binder
Slides
Soil
Loose, unsatu-
25
(2.1 : 1)
M
L
6.5
Abundant (10,000
avalanches
rated sands
to 100,000 in the
40 earthquakes)
Disrupted
Loose, unsatu-
15
(3.7 : 1)
M
L
4.0
Very abundant
soil slides
rated sands
(more than
100,000 in the
40 earthquakes)
Soil slumps
Loose, partly
10
(5.7 : 1)
M
L
4.5
Abundant (10,000
to completely
to 100,000 in the
saturated sand or
40 earthquakes)
silt; uncompacted
or poorly com-
pacted artificial
fill composed of
sand, silt, or clay,
preexisting soil
slump deposits
Soil block
Loose, partly or
5
(11 : 1)
M
L
4.5
Abundant (10,000
slides
completely satu-
to 100,000 in the
rated sand or silt;
40 earthquakes)
uncompacted or
slightly compacted
artificial fill com-
posed of sand or
silt, bluffs contai-
ning horizontal
or subhorizontal
layers of loose, satu-
rated sand or silt
Flow slides
Slow earth
Stiff, partly to
10
(5.7 : 1)
M
L
5.0
Uncommon (100
and lateral
flows
completely satu-
to 1000 in the 40
spreading
rated clay and
earthquakes)
preexisting earth
flow deposits
Flow slides
Saturated, uncom-
2.3
(25 : 1)
M
L
5.0
Moderately
pacted or slightly
a
max
0.10
g
common (1000
compacted artificial
to 10,000 in the
fill composed of
40 earthquakes)
sand or sandy silt
(including hydraulic
fill earth dams and
tailings dams);
loose, saturated
granular soils
