In a large part of South America, slow landslides are triggered by extreme hydrometeorological conditions leading to, for instance, Rainfall-Induced Landslides – RILs. These RILs are common in urban areas and have a negative impact on the population and infrastructure development. Despite their importance, these events are little understood. We aimed at understanding the spatial distribution of RILs in the urban zone of Temuco, Chile (38.8°S, 72.6°W). The area has the typical hydrometeorological conditions of southern Chile. We conducted our assessment with a temporal analysis of shallow deformations, obtained by synthetic aperture radar interferometry (Sentinel 1 A/B). These shallow deformation rates were compared with satellite precipitation data (CHIRPS product) and electrical resistivity tomography (ERT). We identified active RIL-prone zones with deformation rates greater than 60 mm during the period 2014 to 2017, supporting theories of hydrometeorological control. Slow movements were observed in volcanic soils, suggesting the influence of their geotechnical characteristics. Our results can be extrapolated to the southern Andes (35°S-43°S), where a large number of volcanic-sedimentary units are susceptible to RILs. Finally, integration of our multidisciplinary approach will facilitate understanding of the local RIL dynamics, allowing a better risk management to decision-makers in South American and other developing countries.
Applications of resistivity tomography to hydrologic problems in the urban areas of Salvador, Bahia State, Brazil