Risk assessment of fast landslide – From theory to practice

Fast landslides often cause victims and huge economic damages because of the large distance that is rapidly covered by instabilised soil masses and the weakness of the advance warning for the first-failure stage. The reduction of the fatal consequences produced by these phenomena is, therefore, a relevant goal which implies, however, several difficulties due to the complexity of both the instability phenomena and the risk assessment. Hence, it is frequently necessary to adopt simplified procedures which must be selected bearing in mind the aim to be pursued. After some preliminary considerations on the characteristics of fast slope movements, the paper briefly reviews the risk theory and some of the available methods for risk factors evaluation. Therefore, some case histories are discussed in order to show that, notwithstanding the mentioned difficulties, it is possible to obtain, from a practical point of view, reliable results with reference both to land-use planning and risk control.