Mapping Geological at-Risk Areas in the City of São Paulo: Issues and Results from the Largest Risk Survey in Brazil

Since the 1980s the risk studies have definitely been unable to follow the growth and the density of favelas, and some communities have started to trigger the first records of accidents in areas hitherto stable. The mapping made in 2010 is today the largest geological-risk database in the country. Besides technical information, the survey has also shown the types of intervention to be implemented according to the degree of risk and the type of verified occupation, – vital data to prioritizing the public-authority actions. Out of 1,602 favelas and informal settlements in the city, 25% have currently occupied areas with some occurrence probability of mass-movement processes. Together, the assessed areas cover about 13.5km², located in the outskirt regions. Nowadays, about 115,000 people are living in landslide-prone areas in the capital. As a result, the low-income intervention projects by the government have been reassessed and adjusted, prioritizing housing, social-educational infrastructure, and basic-sanitation actions in areas of greatest susceptibility.