Landslide fatalities and the evaluation of landslide risk in Italy
Introduction
Much of Italy consists of hilly and mountainous terrain subject to landslides of different types and sizes. Although numerous studies have described individual landslides, landslide types, or landslide distribution and abundance in different geographical and physiographical regions, little is known about landslide risk to human beings.
Landslides kill people almost every year in Italy. From 1920 to 1999, only in 1944 and 1995, have landslides casualties not been reported. Between 1990 and late 1999, at least 263 people were killed by mass movements, an average of 26 deaths per year. Catenacci (1992) estimated that at least 2447 lives were lost in the period 1945–1990. Analysis of the AVI landslide archive (Guzzetti et al., 1994, Reichenbach et al., 1998) indicates that this is a low estimate and suggests that in Italy, the proportion of the population exposed to landslide risk is large. This work attempts to provide a quantitative estimate of landslide risk in Italy by analysing a catalogue of historical landslide events that have caused loss of life, missing persons, injuries and homelessness.
Section snippets
Sources of information
A database of landslides that have caused death, missing people, injuries and homelessness in Italy was assembled in 1999 from a variety of different sources including existing catalogues and archives on landslides, reports of meteorological and seismic events that triggered slope failures, and accounts or descriptions of individual landslide events. The main source of information was the National Research Council's AVI project archive, a database of information on landslide and flood events
General considerations
The historical catalogue spans the 720 years that extend from 1279 to 1999 and lists a total of 995 landslide events that caused casualties, including events for which the number of casualties is unknown. This is equivalent to a landslide disaster every 0.7 years, or an annual frequency of 1.38. Selecting only the events that caused three or more deaths or missing people (Evans, 1997), the number of landslide disasters falls to 303, and the frequency reduces to one every 2.37 years. Between 1410
Conclusions
Landslides may be triggered by a variety of different factors, including high-intensity or long-duration rainfall, snowmelt, seismic shaking, land-use changes, or human actions. Movements vary in size and character from small rocks falling off a cliff to deep-seated landslides that extend for several square kilometres. Slope movement velocities range from almost undetectable (mm/year) to hundreds of kilometres per hour. Many different types of slope failure have proved to be capable of killing
Acknowledgements
The work of numerous people who contributed to the compilation of the AVI database is acknowledged, and particularly the contribution of Francesco Cipolla and Stefania Pagliacci. I am grateful to Mariano Sartore for providing historical population records. I am also grateful to David Alexander, Earl Brabb, Alberto Carrara, and Andy Hansen for reading drafts of the manuscript; and to Robin Fell and Theo van Asch for reviewing the paper. The research was supported by CNR-GNDCI grants to Unità
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