Landslide Susceptibility

Caution: A disadvantage of a heuristic fuzzy approach to the creation of the map is that the output is a “possibility,” which is not strictly comparable to the probabilities generated by classical statistics; several features of the map thus may limit its use. First, the resolution of the map is approximately 1 km, and terrain varies significantly within many pixels. The choice to aggregate slope by computing the maximum value means that some pixels may contain a very small area of steep terrain, while the remainder is not susceptible to landslides. Second, the use of biased and incomplete landslide inventories to evaluate the susceptibility map makes the results more difficult to interpret. Third, the Geological Map of the World is only appropriate for use over very large areas. At local and national scales, more detailed information is often available, but it varies in quality, format, and cost. Fourth, this map models all mass movements with the same treatment. The real world is more complex, and factors that drive rock toppling in Canada are not the same as those which can cause debris flows in New Guinea. Fifth, this map does not provide an explicit hazard level in the form of an annual probability of slope failure. Therefore it is very likely that landslides will occur at some date in all of the very highly susceptible locations, but the size, frequency, and timing of those events are not known. These limitations suggest that the global susceptibility map is best used for a few purposes: situational awareness of global landslide hotspots and potential occurrence, the development of global decision support systems, and prioritization of future landslide research. It is not appropriate for decisions about infrastructure design, building code legislation, or local land use planning.