The Inform@Risk project aims to develop a cost‐effective but sufficiently accurate, easy‐to‐maintain early warning system (EWS) for informal settlements on the margins of large cities, adapted to tropical climatic conditions in South American mountain regions. This EWS will be implemented on the outskirts of the Bello Oriente district in Medellín. The area is characterized by an elevation of around 2,000 m, a medium slope inclination of 20° to 30° and deeply weathered crystalline rocks, which are particularly sensitive to shallow landslides during heavy precipitation. In addition to the development of a geo‐sensor network with complex data integration and real‐time evaluation, the main focus of the project is the social integration of the EWS both with the municipal authorities, which are going to take over the system after completion of the three‐year project, and with the population living in the settlement. This report describes the project and the specifications of the EWS and presents first results from the field work.

The current study site of the project Inform@Risk is located at a landslide prone area at the eastern slopes of the city of Medellín, Colombia, which are composed of the deeply weathered Medellín Dunite, an ultramafic Triassic rock. The dunite rock mass can be characterized by small-scale changes, which influence the landslide exposition to a major extent. Due to the main aim of the project, to establish a low-cost landslide early warning system (EWS) in this area, detailed field studies, drillings, laboratory and mineralogical tests were conducted. The results suggest that the dunite rock mass shows a high degree of serpentinization and is heavily weathered up to 50 m depth. The rock is permeated by pseudokarst, which was already found in other regions of this unit. Within the actual project, a hypothesis has for the first time been established, explaining the generation of the pseudokarst features caused by weathering and dissolution processes. These parameters result in a highly inhomogeneous rock mass and nearly no direct correlation of weathering with depth. In addition, the theory of a secondary, weathering serpentinization was established, explaining the solution weathering creating the pseudokarst structures. This contribution aims to emphasize the role of detailed geological data evaluation in the context of hazard analysis as an indispensable data basis for landslide early warning systems.

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Abstract. The global number of vulnerable citizens in areas of landslide risk is expected to increase due to the twin forces of climate change and growing urbanization. Self-constructed or informal settlements are, due to shortage of urban land, frequently built in hazardous terrain such as landslide-prone slopes. They are characterized by high dynamics of growth, simple construction methods, strong social dynamics, and are exposed to unsteady political approaches. Landslide Early Warning Systems (LEWS) can contribute to decrease their vulnerability, but precise, affordable and culturally integrated LEWS need to be further developed. In this paper, we present a four-year living lab research project that aimed to design, implement, and evaluate a LEWS in the neighborhood of Bello Oriente, located in the urban-rural border of Medellín, Colombia. Its research team is composed of landscape architects, geo-engineers, remote sensing and geo-informatic experts. The research team collaborated with a multitude of stakeholders: civil society, private enterprises, non-governmental agencies and various branches of government. A prototypical LEWS has been designed, implemented and handed over to the government. It has entered a test and calibration phase. First findings indicate that the integrative development of technical aspects of a LEWS in informal settlements can be challenging, but manageable; whereas, the social and political support can vary and be beyond the control of the designer. It can be concluded that a resilient LEWS for informal settlements has to achieve sufficient social and technical redundancy to maintain basic functionality even in a reduced support scenario.