Abstract. Located in a mountainous area of south-eastern Brazil, the municipality of Campos do Jordão has been hit by several landslides in recent history. Among those events, the landslides of early 2000 were significant in terms of the number of deaths (10), the population affected and the destruction of infrastructure that was caused. The purpose of this study is to assess the relative contribution of natural and human factors to triggering the landslides of the 2000 event. To achieve this goal, a detailed geotechnical survey was conducted in three representative slopes of the area to obtain geotechnical parameters needed for slope stability analysis. Then, a set of numerical experiments with GEO-SLOPE software was designed, including separate natural and anthropic factors. Results showed that natural factors, that is, high-intensity rainfall and geotechnical conditions, were not severe enough to trigger landslides in the study area and that human disturbance was entirely responsible for the landslide events of 2000. Since the anthropic effects used in the simulations are typical of hazardous urban areas in Brazil, we concluded that the implementation of public policies that constrain the occupation of landslide susceptible areas are urgently needed.

No abstract

Natural hazards, occurring all over the world, may become a disaster when humans and nature interact. In Brazil, landslides triggered by heavy rainfall are the most common phenomenon that affects the population. Due to the economic and social losses and deaths, the identification and monitoring of risk areas are extremely important. Therefore, this study aims to identify the landslide-susceptible areas in Vila Albertina and Britador neighborhood, located in Campos do Jordão city in São Paulo state, Brazil. Using the Shalstab mathematical model, which analyzes the slope stability, and satellite images from World-View-2 sensor with data mining techniques, it was identified the most susceptible areas for this phenomenon and the main characteristics of human occupation that might induce landslides. To achieve this goal, three scenarios were simulated for each neighborhood, changing the values of the geotechnical parameters, used as input on Shalstab. The results of susceptibility areas were consistent with the reality observed in these neighborhoods and the landslide scars corroborate with the assumption that anthropic changes induce landslides. The satellite image allowed the identification of different types of human interaction and its changes in steep slope areas.

The municipalities of Ubatuba, Campos do Jordão, and São José dos Campos are located in the region of São Paulo State (Brazil). These municipalities are recognized nationally for having an elevated number of recorded landslides on slopes and embankments. In addition, these municipalities contain multiple areas that are at risk for landslides. Various soil landslides occurred in these municipalities in January 2013, when real-time climactic and geotechnical variables were monitored by automatic rain gauges, humidity sensors and soil temperature and suction devices. The resulting data were used to understand the functions of each variable in the occurrence of landslides. Analyses of rainfall, humidity and soil temperature were used with field investigations to formulate a hypothesis regarding the predominant rupture mechanism and the role of each monitored variable in the deflagration of the soil landslides that occurred in the three studied municipalities. The geotechnical variable data revealed that both temperature and soil moisture contents played fundamental roles in the deflagration of shallow planar landslides in urban areas. The hourly rain intensity and/or rainfall accumulation for 24 and/or 72 h were responsible for the deflagration of the landslides that occurred in the studied areas, along with the existing anthropic constraints in the risk areas. Significant variations did not occur in the soil suction data during the landslides, principally due to the unsatisfactory sensor precision when reading field suction between −10 and −100 kPA (±25%).

Agradeço primeiramente a Deus, que sempre me deu muita saúde, paz espiritual, motivação, sabedoria e iluminou meu caminho, sem os quais eu certamente não teria superado os diversos obstáculos encontrados nessa jornada. Ao professor Fernando Marinho pelo grandioso e constante apoio, incentivo e orientação no decorrer do desenvolvimento dessa pesquisa, e pela confiança na minha capacitação, num momento muito importante da minha vida e carreira profissional. À professora Maria Cristina Motta de Toledo do Instituto de Geociências da USP, pelo precioso auxílio nos trabalhos de campo e nas análises de micromorfologia. Ao professor Renato Luiz Prado do Departamento de Geofísica do IAG-USP, pela realização e interpretação dos ensaios geofísicos. Aos professores Marcos Massao Futai e Carlos de Sousa Pinto, pelas valiosas sugestões quando foram solicitados no decorrer dessa pesquisa. Aos professores do programa de pós-graduação cujos ensinamentos transmitidos foram imprescindíveis para a ampliação do meu conhecimento na área de engenharia geotécnica. Ao Instituto Geológico (Processo SMA 30.120/05) e à FAPESP (Processo nº 05/55736-5) pelo apoio financeiro concedido para a realização dessa pesquisa. Aos amigos e pesquisadores da Seção de Geologia Aplicada e Ambiental do Instituto