Assessment of landslide occurrences in Serra do Mar mountain range using kinematic analyses

Abstract

Due to its meteorological, geological and geomorphological settings, Brazilian's Atlantic coast have suffered severe landslide phenomena, particularly along the cost of São Paulo, Rio de Janeiro, and Santa Catarina states. Studies have shown that these processes are complex and triggered by several factors. However, within the study area, many landslide locations are placed on gneiss migmatitic terrain with pronounced geological discontinuities. The objective of this paper is to assess landslide occurrences in Serra do Mar (Caraguatatuba, SP) and investigate, by means of kinematic analysis, how they correlate with foliation and fractures present on the rocks. Kinematic analysis is used to investigate which discontinuities are more favorable to landslides occurrence and their relationship with slope directions. Structural information and kinematic data models are used to evaluate cause-effect relationship of landslide processes. Results show that dip slopes, with NE-SW direction, have greatest potential for the occurrence of planar landslides. On the other hand, anti-dip and cross-dip slopes have a greater potential to develop wedge landslides. Rock weathering and fluid flux along foliation planes can intensify mass movement. Such effect is also seen in residual soil, since they are able to preserve relict structures of the rock. This study contributes to a better understanding of how geological structures, preserved in tropical residual soils, influence shallow landslides.

Geological-Geotechnical Characterization of Slopes Belonging to the Serra do Mar Paranaense, Brazil

“…The area includes relief units from the First Plateau Paranaense and the morphosculptural sub-unit of the Serra do Mar Paranaense. The study of hydrographic basins supplies relevant information to the research, for further analysis of rainfall distribution at slope stability (Soares et al, 2012;Vilanova, 2015;Gonzalez, 2017;Cerri et al, 2018;Vieira et al, 2018).…”

“…The relief, with strongly corrugated morphology in this environment, favors the occurrence of residual soils in the upper third portion of the slopes, conditioned by the incipient pedogenesis development associated to the action of the surface runoff. Thus, these soils have characteristics linked with the original material, represented by variable granite lithotypes, migmatites and gneisses (Furlan et al, 2011;Cerri et al, 2018). The colluvial soils, on the other hand, may be found in the lower two-thirds of the slopes, where they gain depositions from upwind and upstream erosive processes.…”

“…Serra do Mar is a mountain range encompassing approximately 1,500 km of the East/South coast of Brazil, going from the state of Rio de Janeiro to the North of the state of Santa Catarina (Cerri et al, 2018;Vieira et al, 2018). The range is classified into three large geomorphological compartments: Plains Compartment, Mangrove Compartment and Mountain Ranges and Hills Compartment, characterized by a diversity of lithological types, including granites, schists, gneisses and migmatites (Massad, 2010).…”

“…Listo & Vieira (2015) state that Serra do Mar is one of the most important reliefs of Brazil, both in geomorphologic terms when described as a function of its genesis and evolution, and by its strategic importance, in connecting the largest import and export harbors of the South and Southeast regions, as the port of Santos, the busiest in South America (Vieira et al, 2018). As such, it has a dense network of communication and important service routes supporting economic development, for example: roads, railways, water pipelines, gas pipelines, transmission lines, urban installations and energy industries (Cerri et al, 2018). Thus, a varied research has been and is being performed in this region, from which several questions have arisen, for example, if the results from the models will be more efficient with the use of geotechnical values collected in situ (Listo & Vieira, 2015).…”

“…Some studies have described the geological and geotechnical characteristics of the soils found along the Serra do Mar in order to obtain parameters as internal friction angle, cohesive intercept, granulometric distribution, hydraulic conductivity and structural features (Mendes et al, 2006;Furlan et al, 2011;Mendes et al, 2015;Sestrem et al, 2015;Advincula, 2016;González et al, 2017;González, 2017;Cerri et al, 2018;Vieira et al, 2018;Trevizolli, 2018) looking to increase the knowledge about the region.…”