UseCase

Ground instabilities may cause significant physical and socio-economic damage in many hilly and mountainous regions of the world. For instance, in Italy, about 500 people have been killed and 25000 people impacted by landslides over the past 25 years . Risk associated with ground movements is expected to increase in the next decades because of (i) growing development and inappropriate land use in landslide prone areas, (ii) increasing frequencies of extreme hydro-meteorological events (storms, hurricanes, floods…) estimated as an effect of climate change. Landslide hazard and risk assessments are essential for effective planning and management to reduce landslide-related losses.

Hazard is the probability of occurrence of a potentially damaging phenomenon within a given period of time and a given area. Landslide hazard assessment aims at answering these questions:

  • Where are the dangerous zones subject to landslides?
  • What are the probabilities of these zones being affected by landslides?
  • What are the typologies and intensities of these landslides?

Risk is a measure of the probability and severity of the damage caused by a phenomenon to elements at risk (human life, property, environment...). For example, risk regarding life loss can be expressed as the annual probability of fatalities caused by landslides in a given location. Landslide risk is evaluated from the outcomes of landslide hazard assessment and the vulnerabilities of elements at risk. Landslide risk assessment addresses these questions:

  • What are the elements at risk which may be damaged by landslides?
  • What are their probabilities of being damaged?
  • What is the probable severity of the damage?

Hazard and risk assessment tools are required to help decision making in most steps of the disaster management cycle , including phases before, during and after a crisis:

  • Prevention (defining acceptable risk, land use and development planning)
  • Mitigation (public information and education, engineering measures)
  • Preparedness (setting monitoring and alerting systems, preparation of civil security plans)
  • Development (improving land use and development planning).