ABSTRACT
A Multiple Occurrence Regional Landslide Event (MORLE) in the Itajaí valley (Santa Catarina State, Brazil) took place on November 2008. The nature of the event, conditioning factors and effects caused are briefly described. Over 1600slope movements occurred, most of which concentrated within an area of about 300 km2, with important losses of lives and material damages. On the basis of existing—and limited—information on the event and its conditioning factors, an analysis of the relationship between landslide ruptures and conditioning factors was carried out to provide predictions in the case of future events. A heuristic susceptibility model, based to a great extent on expert opinion acquired through field work, was built.
In order to test the former model, another one, based on Favourability Functions, was obtained and validated. Results obtained with both types of models were then compared. The best results were obtained with the probabilistic model. The results show the heuristic approach can provide useful predictions with the amount and type of information available. Similar MORLE events have occurred in this state and others of southern Brazil during the last few decades, and they could provide the basis for similar analyses and formulation of hazard scenarios.
The methodology used and results obtained are presented and discussed.
