Where we should not expect landslides?

Landslide susceptibility is the propensity of a territory to generate landslides.

Many methods are available to determine landslide susceptibility, whereas only a few attempts were made to outline areas not likely to generate landslides i.e., non-susceptible landslide areas. This is surprising, because for planning purposes it is just as important (if not more important) to know where landslides are not expected than to know where landslides may occur.

We have developed a simple statistical method to delineate areas not susceptible to landslides, and we applied the method in Italy and in the landmasses surrounding the Mediterranean Sea.

Our method uses only two variables: local terrain slope and relative relief i.e., the maximum elevation difference in an area. We calculate both variables from a digital terrain model (DTM), a numeric representation of the terrain.

Using 13 landslide maps produced over the years by our research team in nine regions in Italy, we determined a statistical relationship between the lack of landslides ant the local slope and general relative relief. Next, we applied the relationship to the whole of Italy producing a national map showing non-susceptible areas.

Later, we extended the mapping to an area of more than five million square kilometres surrounding the Mediterranean Sea. Tests bade using landslide data in two study areas in Spain have demonstrated the reliability of our non-susceptibility landslide map for the Mediterranean area.

Further details

Marchesini I, Ardizzone F, Alvioli M, Rossi M, Guzzetti F. 2014. Non-susceptible landslide areas in Italy and in the Mediterranean region. Natural Hazards and Earth System Sciences 14(8) : 2215-2231. DOI: 10.5194/nhess-14-2215-2014.