Evaluation of the Susceptibility Chart to Gravitational Mass Movements Using Geotechnical Soil Characterization Tests

The main cause of natural disasters in Brazil is gravitational mass movements, and among these, landslides stand out. In this context, the geomorphological region known as Serra do Mar, between the states of Paraná and natural disasters and, mainly, landslides, daily affect Rio de Janeiro. The Brazilian Geological Survey (SGB-CPRM) develops numerous programs, providing the community with products aimed at disaster prevention and urban planning. Among these, the Susceptibility Maps to Gravitational Mass Movements and Floods, which aim to analyse the degree of natural susceptibility of a terrain to the occurrence of gravitational mass movements and hydrological processes, such as floods, play an important role in municipal urban planning. This work aims to analyse the susceptibility map, by carrying out geotechnical characterization tests, seeking to confirm the assertive potential of the susceptibility map and its methodology. To this end, the study was based on soil characterization through tactile-visual field analyses and geotechnical characterization tests in the municipality of Itaóca, SP, in the region known as Vale do Ribeira and located in the Serra do Mar domain. The region was selected due to its geomorphology with steep slopes and numerous landslides recorded in the rainy event that occurred in January 2014, when torrential rains in the Guarda-Mão and Gurutuba river basins triggered a large number of landslides, causing debris flows and claiming approximately twenty-five lives in the municipality. Thus, the work allowed us to identify, in a pilot area, the usability of the susceptibility map to prevent disasters and plan the occupation of new areas in Brazilian municipalities.

Keywords: Soils, Susceptibility, Landslides.