Landslides triggered by the November 2002 rainfall event, Lombardy, Italy

An important meteoric event occurred during November 2002 in the Central Italian Alps. Prolonged intense rainfall were recorded in the prealpine sector of Lombardy. More than 800 mm fell in a 17 days period during November. More than 250 landslides were mapped in the area. The mapped instabilities are, namely: small soil slips, soil slip/debris flows, debris flows and debris torrents, large debris slides and avalanches, earth flows and deep seated slope. Large slope instabilities have been reactivated (Mt. Legnoncino and Legnone areas) during this event and are still in motion after two months. These instabilities are endangering very large areas because of their position high on the slopes, the involvement of very weak rocks and weakly cohesive soils, the involved volumes amounting to some millions of cubic metres. Villages, structures and infrastructures (railway, highway, etc.) have been directly affected by the movements with relevant damages. The landslide inventory map produced for this event has been compared with a recently inventory map completed for the same region. Landslide distribution has been compared with rainfall distribution during the entire period. Some of the landslides have been mapped and monitored with major detail and geomechanical modelling has been performed. This contribution stresses the increase in number of events, during the last years and in particular of their relevance and impact, in the prealpine and alpine sectors of the Lombardy Region.