High mountain regions often face a multitude of natural hazards, the combined effects of which, known as "cascading hazards", can have serious consequences for infrastructure and urban areas.
However, there is a lack of tools to prevent and quantify these complex risks. That’s why researchers across several countries have collaborated to develop an innovative way to calculate rockfall risk over large areas of very high mountains affected by high seismic activity. The major challenge of this work? Quantify these risks in a detailed and exhaustive manner.
This new method addresses this challenge in an innovative way, taking into account a wide range of exposed assets (people, dwellings, flowing vehicles, lifelines) and considers both the rockfall risk associated with earthquakes and the "common" rockfall risk resulting from erosion and local climatic conditions.
Earthquakes account for nearly 60% of the rockfall risk in the AndesFor example, one of the major findings of this study is that nearly 60% of the total rockfall hazard in the Andean zone studied is attributable to seismic activity. It is therefore crucial to consider the rockfall risk when large earthquakes occur in this area.
This method has been successfully tested in the Andes Mountains in Chile, providing promising results. These results show that it is now possible to assess the risk of rockfalls in the mountains in a more comprehensive manner. Experts can now identify which places are most at risk, such as villages and stretches of roads that are exposed. This advance represents an important step towards better prevention of rockfalls in mountainous areas, offering valuable tools to anticipate and reduce the consequences of these events on infrastructure and communities.
1) A natural hazard is the result of the combination of a hazard (dangerous natural phenomenon, in this case falling rocks) and a geographical area where there are issues that can be human, economic or environmental.
Watch out, rockfalls!
Rockslides and rockfalls are rapid ground movements resulting from the action of gravity on rock elements.
A distinction is made between: rockfalls (volume less than 1 dm3); rockfalls (volume greater than 1 dm3); landslides (volume greater than 100 m3); mass collapses (volume of up to several million m3).
1 Un risque naturel résulte de la conjonction d’un aléa (phénomène naturel dangereux, ici chute de blocs) et d’une zone géographique où existent des enjeux qui peuvent être humains, économiques ou environnementaux.
Reference Manon Farvacque, Nicolas Eckert, Gabriel Candia, Franck Bourrier, Christophe Corona, David Toe. Holistic rockfall risk assessment in high mountain areas affected by seismic activity: application to the Uspallata valley, Central Andes, Chile. Risk Analysis, doi.org/10.1111/risa.14239