The evolution of Risk from Landslides: Concepts and Applications for Communities in New Zealand

<p>The aim of this research is to identify temporal changes of risk from landsliding for several locations in New Zealand (the Western Hutt Hills, close to Wellington; Te Arai, close to Gisborne; Mt.Cook/Aoraki Village, South Island). While risk analysis usually targets a particular point in time, this research includes several five-year intervals (based on census years) starting in 1981 until 2006. The scale of this analysis is the community level. Risk is not expressed as an absolute level of loss, for example a dollar value or the number of fatalities. Risk is rather considered as the probability and extent of adverse effects on a community inferred from landsliding. As such, risk is relative: the aim is to quantify risk for a community relative to another point in time, and relative to other communities. In addition, the degree to which risk levels vary between communities is quantified. The objectives of the risk analysis are to: 1. establish landslide hazard, i.e. the frequency and magnitude of landsliding for each location, 2. develop an index of social vulnerability per census year and community, 3. develop an index of social resilience per census year and community, 4. combine 1.-3. and, together with exposure ('elements at risk'), determine risk from landsliding for each community through time.</p>