Landslide Hazard Report_compressed

                            AUSTRALIAN GEOGUIDE LR7 (LANDSLIDE RISK)

Risk to Life
                                                                            developed areas, where works can be carried out as
Most of us have some difficulty grappling with the                          part of the development to limit risk. The tolerable level
concept of risk and deciding whether, or not, we are
                                                                            is raised to 1:10,000 in established areas, where
prepared to accept it. However, without doing any sort                      specific landslide hazards may have existed for many
of analysis, or commissioning a report from an "expert",                    years. The distinction is deliberate and intended to
we all take risks every day. One of them is the risk of                     prevent the concept of landslide risk management, for
being killed in an accident. This is worth thinking about,                  its own sake, becoming an unreasonable financial
because it tells us a lot about ourselves and can help to                   burden on existing communities. Acceptable risk is
put an assessed risk into a meaningful context. By                          usually taken to be one tenth of the tolerable risk
identifying activities that we either are, or are not,                      (1:1,000,000 for new developments and 1:100,000 for
prepared to engage in we can get some indication of                         established areas) and efforts should be made to attain
the maximum level of risk that we are prepared to take.                     these where it is practicable and financially realistic to
This knowledge can help us to decide whether we really                      do so.
are able to accept a particular risk, or to tolerate a
particular likelihood of loss, or damage, to our property                                   TABLE 3: RISK TO LIFE
(Table 2).
                                                                             Risk (deaths per        Activity/Event Leading to
In Table 3, data from NSW for the years 1998 to 2002,                         participant per                  Death
and other sources, is presented. A risk of 1 in 100,000                            year)              (NSW data unless noted)
means that, in any one year, 1 person is killed for every
100,000 people undertaking that particular activity. The
NSW data assumes that the whole population                                   1:1,000              Deep sea fishing (UK)
undertakes the activity. That is, we are all at risk of
being killed in a fire, or of choking on our food, but it is                 1:1,000         to
                                                                                                  Motor cycling, horse riding ,
reasonable to assume that only people who go deep                            1:10,000
                                                                                                  ultra-light flying (Canada)
sea fishing run a risk of being killed while doing it.
                                                                                                  Motor vehicle use
It can be seen that the risks of dying as a result of                        1:23,000
falling, using a motor vehicle, or engaging in water-
related activities (including bathing) are all greater than                  1:30,000             Fall
1:100,000 and yet few people actively avoid situations
where these risks are present. Some people are averse                        1:70,000             Drowning
to flying and yet it represents a lower risk than choking
to death on food. Importantly, the data also indicate                        1:180,000            Fire/burn
that, even when the risk of dying as a consequence of a
particular event is very small, it could still happen to any                 1:660,000            Choking on food
one of us any day. If this were not so, no one would
ever be struck by lightning.
                                                                             1:1,000,000          Scheduled airlines (Canada)
Most local councils and planning authorities that
stipulate a tolerable risk to property also stipulate a                      1:2,300,000          Train travel
tolerable risk to life. The AGS Practice Note Guideline
recommends that 1:100,000 is tolerable in newly                              1:32,000,000         Lightning strike


More information relevant to your particular situation may be found in other AUSTRALIAN GEOGUIDES:


                                                                        •      GeoGuide LR6 - Retaining Walls
    •    GeoGuide LR1     - Introduction
                                                                        •      GeoGuide LR8 - Hillside Construction
    •    GeoGuide LR2     - Landslides
                                                                        •      GeoGuide LR9 - Effluent & Surface Water Disposal
    •    GeoGuide LR3     - Landslides in Soil
                                                                               GeoGuide LR10 - Coastal Landslides
    •    GeoGuide LR4     - Landslides in Rock
                                                                        •      GeoGuide LR11 - Record Keeping
    •    GeoGuide LR5     - Water & Drainage



The Australian GeoGuides (LR series) are a set of publications intended for property owners; local councils; planning authorities;
developers; insurers; lawyers and, in fact, anyone who lives with, or has an interest in, a natural or engineered slope, a cutting, or an
excavation. They are intended to help you understand why slopes and retaining structures can be a hazard and what can be done with
appropriate professional advice and local council approval (if required) to remove, reduce, or minimise the risk they represent. The
GeoGuides have been prepared by the Australian Geomechanics Society, a specialist technical society within Engineers Australia, the
national peak body for all engineering disciplines in Australia, whose members are professional geotechnical engineers and engineering
geologists with a particular interest in ground engineering. The GeoGuides have been funded under the Australian governments’
National Disaster Mitigation Program.




                              Australian Geomechanics Vol 42 No 1 March 2007                                     173