SLIDE (Wellington): vulnerability of dwellings to landslides (Project No. 16/SP740)

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 Massey, C.I.; Thomas, K.-L.; King, A.B.; Singeison, C.; Taig, T.; Horspool, N.A. 2019 SLIDE (Wellington): vulnerability of dwellings to landslides (Project No. 16/SP740). Lower Hutt, N.Z.: GNS Science. GNS Science report 2018/27. 76 p.; doi: 10.21420/G2DD2Q

The aim of this research was to quantify the vulnerability of people and dwellings to the types of landslide hazards affecting Wellington and other parts of New Zealand. This research comprised two main objectives:

  1.  Investigate what landslide intensity metric(s) best correlate with the different consequences such as economic loss and/or physical damage state; and
  2. Develop appropriate correlations/relationships between the preferred hazard intensity metric(s) and consequence type.

In this study, vulnerability is defined as the degree of loss to a given element or set of elements within the area affected by a hazard. It is expressed on a scale of 0 (no loss) to 1 (total loss). Vulnerability has been evaluated by observing the relationships between:

  • The  characteristics  of  the  element(s),  which  may  make  them  susceptible to damage from a natural hazard;
  • the hazard magnitude or intensity, such as the height, velocity, kinetic energy or pressure  of  the  landslide  debris  on  impact  with  the  element(s)  exposed  to  the  hazard;
  • as well as the consequence of the element(s) being impacted by the hazard, which is expressed as damage or loss.

These relationships, therefore allows us to determine the likely damage or loss to an element(s) from the potential landslide hazards it might be subjected to and is useful for insurance purposes. In this study, empirical data from the New Zealand’s Earthquake Commission insurance claims database was used to evaluate the expected level of economic loss and physical damage to dwellings and people in them, from different landslide types and intensities. Economic loss is expressed as a damage ratio (repair cost divided by replacement value), physical damage is expressed as a damage state, and the threshold damage state at which people are killed in dwellings was also investigated. (auth)