Appendix B - Geotechnical Investigation Report

                                    LANDSLIDE RISK MANAGEMENT
                                  Definition of Terms and Landslide Risk

 Risk Terminology          Description
 Acceptable Risk           A risk for which, for the purposes of life or work, we are prepared to accept as it is with no regard to its
                           management. Society does not generally consider expenditure in further reducing such risks justifiable.
 Annual Exceedance         The estimated probability that an event of specified magnitude will be exceeded in any year.
 Probability (AEP)
 Consequence               The outcomes or potential outcomes arising from the occurrence of a landslide expressed qualitatively
                           or quantitatively, in terms of loss, disadvantage or gain, damage, injury or loss of life.
 Elements at Risk          The population, buildings and engineering works, economic activities, public services utilities,
                           infrastructure and environmental features in the area potentially affected by landslides.
 Frequency                 A measure of likelihood expressed as the number of occurrences of an event in a given time. See also
                           ‘Likelihood’ and ‘Probability’.
 Hazard                    A condition with the potential for causing an undesirable consequence (the landslide). The description
                           of landslide hazard should include the location, volume (or area), classification and velocity of the
                           potential landslides and any resultant detached material, and the likelihood of their occurrence within
                           a given period of time.
 Individual Risk to Life   The risk of fatality or injury to any identifiable (named) individual who lives within the zone impacted
                           by the landslide; or who follows a particular pattern of life that might subject him or her to the
                           consequences of the landslide.
 Landslide Activity        The stage of development of a landslide; pre failure when the slope is strained throughout but is
                           essentially intact; failure characterised by the formation of a continuous surface of rupture; post failure
                           which includes movement from just after failure to when it essentially stops; and reactivation when the
                           slope slides along one or several pre-existing surfaces of rupture. Reactivation may be occasional
                           (eg. seasonal) or continuous (in which case the slide is ‘active’).
 Landslide Intensity       A set of spatially distributed parameters related to the destructive power of a landslide. The parameters
                           may be described quantitatively or qualitatively and may include maximum movement velocity, total
                           displacement, differential displacement, depth of the moving mass, peak discharge per unit width, or
                           kinetic energy per unit area.
 Landslide Risk            The AGS Australian GeoGuide LR7 (AGS, 2007e) should be referred to for an explanation of Landslide
                           Risk.
 Landslide                 The classification, and volume (or area) of landslides which exist or potentially may occur in an area or
 Susceptibility            may travel or retrogress onto it. Susceptibility may also include a description of the velocity and
                           intensity of the existing or potential landsliding.
 Likelihood                Used as a qualitative description of probability or frequency.
 Probability               A measure of the degree of certainty. This measure has a value between zero (impossibility) and 1.0
                           (certainty). It is an estimate of the likelihood of the magnitude of the uncertain quantity, or the
                           likelihood of the occurrence of the uncertain future event.
                           These are two main interpretations:
                           (i) Statistical – frequency or fraction – The outcome of a repetitive experiment of some kind like
                               flipping coins. It includes also the idea of population variability. Such a number is called an
                               ‘objective’ or relative frequentist probability because it exists in the real world and is in principle
                               measurable by doing the experiment.




February 2019