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Technical Committee 208 /
Comité technique 208
Table 7. Proposed values of landslide depth intensity parameter
Landslide depth (m)
I'
f-dep
<0.1
0.10
0.1-0.3
0.30
0.3-0.6
0.70
0.6-0.8
0.90
≥0.8
1.00
Table 8. Proposed values of landslide width intensity parameter
Landslide width (m)
I
wid
< 50
0.10
50-200
0.30
200-400
0.50
400-700
0.80
≥ 700
1.00
4 SUSCEPTIBILITY
4.1
Susceptibility of structures
The capacity of a structure to withstand the landslide hazard de-
pends on the morphological characteristics and utilization con-
ditions (Amatruda 2004; Coburn 2002). Four parameters were
considered, including structure type
s
str
, maintenance state
s
mai
,
ratio of service years to design service life
s
ser
and the differ-
ence in the directionality of landslide movement and the princi-
pal longitudinal direction of the structure
s
dir
, with the model
given in Eq. 10. Together, these parameters describe the suscep-
tibility of the structures to be damaged by a landslide (Table 9
for
s
str
,
Table 10 for
s
mai
,
Table 11 for
s
ser
, Table 12 for
s
dir
).
S
s
= 1 – (1 –
s
str
)(1 –
s
mai
)(1 –
s
ser
)(1 –
s
dir
)
(10)
Table 9 Structure susceptibility parameter (Heinimann 1999)
Structural typology
Resistance
s
str
Lightest, simple structures
Very high
1.00
Light structures
High
0.90
Rock masonry and concrete
Medium
0.70
Brick masonry, concrete structures
Low
0.50
Reinforced concrete structures
Very low
0.30
Reinforced structures
Extremely low
0.10
Table 10 Proposed values of maintenance state susceptibility parameter
State of maintenance
s
mai
Extremely good
0.00
Good
0.05
Slight deformation
0.25
Medium deformation
0.50
Serious deformation
0.75
Extremely Serious deformation
1.00
The damage would be most serious when the angle between
the two directions is 0°and be lightest when the angle gets close
to 45° (Table 12).
Table 11 Proposed values of service year susceptibility parameter
Ratio of service year to design service life
s
ser
≤ 0.1
0.05
0.1 - 0.4
0.10
0.4 - 0.6
0.30
0.6 - 0.8
0.50
0.8 - 1.0
0.70
1.0 - 1.2
0.80
> 1.2
1.00
Table 12. Values of directionality difference susceptibility parameter.
Directionality of landslide movement (°)
s
dir
0-5
1.0-0.6
5-15
0.6-0.4
15-30
0.4-0.2
30-45
0.2-0.0
4.2
Human susceptibility
The susceptibility of persons to be hurt or killed by the landslide
depends strongly on the cognitive and reaction capacity upon the
occurrence of a landslide and the protection measures at the site,
e.g. escape routes or early warning system. The following model
was proposed to describe the landslide susceptibility for persons:
S
p
= 1 – (1 –
s
hel
)(1 –
s
age
)(1 –
s
war
)
(11)
where
s
hel
,
s
age
and
s
war
are the susceptibility parameters, health
condition, age and existence of a warning system, respectively.
A person’s health condition, i.e. evacuation capacity, can be
divided into three classes: 1) healthy, 2) weak physical condi-
tion, e.g. chronic disease slowing down movement, and 3) com-
plete incapacitation with inability to evacuate. The susceptibility
parameter values listed in Table 13 are proposed.
On the basis of fatality rate-age distribution data from earth-
quakes, Li (2010) proposed a quadratic polynomial function
(Eq. 12) in terms of age
a
, which was adopted in this paper:
s
age
= 0.95 – 0.00486 [INT(
a
/5) -5]
2
(12)
where INT() is the downward rounded integer function.
Table 13. Proposed values of health condition susceptibility parameter.
Health condition
s
hel
Healthy
0-0.1
Weak physical condition
0.1-0.8
Complete incapacitation
0.8-1.0
“Early warning” refers to all the measures that can be taken
before the occurrence of a catastrophic event reducing the risk
or contributing to avoid it (Table 14). Completeness level in the
table refers to the efficiency of early warning or other mitigation
measures in place to reduce or avoid risk.
5 VULNERABILITY OF PERSONS IN STRUCTURES
When a landslide occurs, the vulnerability of persons in the
structures is directly correlated with the structure damage.
To estimate the casualty level in a building, one needs to as-
sess the proportion of people trapped in the debris of a collapsed
building and the casualty level for different degrees of damage.
When buildings collapse, not all the occupants are trapped
inside. The number of people trapped in a collapsed building
depends on the size and type of building, the collapse itself, the
time of collapse and the escape options during and after the col-
Table 14. Proposed values of “generic” early warning system susceptibility parameter
Completeness level
S
war
Description of risk reduction or risk avoidance measure
None
1.0
Investigate the geological background and deformation of the landslide, without any monitoring measures.
Simple
0.6-1.0 Simple manual monitoring measurements with low precision and measurements at long interval (one month), e.g.
manual measurement of extension velocity of crack and subsidence velocity of head of landslide.
Moderate
0.2-0.6
Accurate monitoring equipment with moderate precision, long interval readings (one month) and low distribution
density of monitoring points; monitoring involves only geological parameters); investigation of population exposed
to landslide risk; simple emergency plan includes warning transmission and evacuation paths.
Comprehensive
0.0-0.2
Accurate monitoring equipment with high precision and close interval readings (one day/one week); density of mo-
nitoring points high enough to sense deformation of entire landslide; monitoring involves geophysical, atmospheric,
hydrodynamic and soil quantities; decision procedures in place based on experience with time prediction, triggering
threshold and evacuation successes/failures with landslide; overview of population and public facilities exposed;
overall emergency plan includes warning transmission, evacuation paths, logistics, medical assistance and so on.
