Response to Information Request - MCU12/0184

                                       PRACTICE NOTE GUIDELINES FOR LANDSLIDE RISK MANAGEMENT 2007

                                                                APPENDIX C: LANDSLIDE RISK ASSESSMENT

                                     QUALITATIVE TERMINOLOGY FOR USE IN ASSESSING RISK TO PROPERTY


   QUALITATIVE MEASURES OFLIKELIHOOD

ApproJ:imate Annual Probability
                                                Implied Indicative Landslide                                                                                                                         Leve.1
                                                                                                                      Description                                           Descriptor
Indicative            Notional                      Recurrence Interval
   Value             Boundary
   10-                                           10 years                               The event is expected to occur over the design life.                          ALMOST CERTAIN                   A
                        5xlO-2                                       20 years           The event will probably      occur   under adverse conditions over the
   10-2                                          100 years                                                                                                            LIKELY                           B
                                                                                        desi~n life.
                        5x10.3                                      200 years
   10-3                                         1000 years                              The event could occur under adverse conditions over the design life.          POSSIBLE                         C
                                                                    2000 vears
                        5xlO-I                                                          Th.e event might occur under very adverse circumstances over the
   10-4                                        10,000 years                                                                                                           UNLIKELY                         D
                                                                                        desi2ll life.
                        5xlO-5                                      20,000 years
   10-’                                                                                 The event is conceivable but only under exceptional circumstances
                                              100,000 years                                                                                                           RARE                             E
                                                                                        over the design life.
                        5xlO-6                                      200,000 years
   10’"                                       1,000,000 years                           The event is inconceivable or fanciful over the design life.                  BARELY CREDIBLE                  F

   Note:      (I)   The table should be used from left to right; use Approximate Annual Probability or Description to assign Descriptor, not vice versa.




   QUALITATIVE MEASURES OF CONSEQUENCES TO PROPERTY

  Approximate Cost of Damage
                                                                                                Description                                                                 Descriptor               Level
 Indicative            Notional
   Value              Boundary
                                             Structure(s) completely destroyed and/or large scale damage requiring major engineering works for                       CATASTROPHIC                      1
   200%
                                             stabilisation. Could cause at least one adiacent property maior consequence dama~e.
                      100%
                                             Extensive damage to most of structure, and/or extending beyond site boundaries requiring significant
   60%                                                                                                                                                               MAJOR                             2
                                             stabilisation works. Could cause at least one adiacent property medium consequence damage.
                        40%
                                             Moderate damage to some of structure, and/or significant part of site requiring large stabilisation works.
   20"10                                                                                                                                                             MEDIUM                            3
                                             Could cause at least one adjacent property minor consequence dama~e.
                         10%
    5%                                       Limited damage to part of structure, and/or nart of site reQuirin~ some reinstatement stabilisation works.              MINOR                             4
                         1%                                                                                                                                                     -




                                             Little damage. (Note for high probability event (AlmostCertain), this category may be subdivided at a
   0.5%                                                                                                                                                              INSIGNIFICANT                     5
                                             notional boundary of 0.1%. See Risk Matrix.)

   Notes:     (2)   The Approximate Cost of Damage is expressed as a percentage of market value, being the cost of the improved value of the unaffected property whi.ch includes the land plus the
                    unaffected structures.
              (3)   The Approximate Cost is to be an estimate of the direct cost of the damage, such as the cost of reinstatement of the damaged portion of the property (land plus structures), stabilisation
                    works required to render the site to tolerable risk level for the landslide which has occurred and professional design fees, and consequential costs such as legal fees, temporary
                    accommodation. It does not include additional stabilisation works to address other landslides which may affect the property.
              (4)   The table should be used from left to right; use Approximate Cost of Damage or Description to assign Descriptor, not vice versa



   91                                                            Australian Geomechanics Vol 42 No 1 March 2007