We present the late Holocene eruption history of the poorly known Doña Juana volcanic complex, in SW Colombia, which last erupted in the twentieth century. This represents a case study for potentially active volcanism in the rural Northern Andes, where tropical climate conditions and a fragmented social memory blur the record of dormant volcanoes. We reconstructed the volcanic stratigraphy of the central-summit vent area by integrating new mapping at 1:5000 scale with radiocarbon ages, sedimentology analysis, and historical chronicles. Our results revealed cyclic transitions from lava-dome growth phases and collapse to explosive Vulcanian and possibly subplinian phases. Pyroclastic density currents were generated by dome collapse producing block-and-ash flows or by pyroclastic fountain/ column collapse and were rapidly channelized into the deeply incised fluvial valleys around the volcano summit. The pyroclastic density currents were ~4–10 × 10⁶ m³ in volume and deposited under granular flow– or fluid escape–dominated depositional regimes at high clast concentrations. In places, more dilute upper portions reached a wider areal distribution that affected the inhabited areas on high depositional terraces. The coefficient of friction (ΔH/L) is higher for block-and-ash flows and dense lava–bearing fountain/low-column-collapse pyroclastic density currents compared to pumice-bearing, column-collapse pyroclastic density currents. Associated mass-wasting processes included syneruptive and intereruptive debris flows, with the last one documented in 1936 CE.

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In the SW flank of the Doña Juana Volcanic Complex, Colombia, the dynamic geomorphic system responds to the complex interaction between volcanic, climatic, and tectonic driving forces, where the recent landscape (last ~20 years) is being shaped as a function of denudational processes. Despite the rapid rates of landforms development, the geomorphology of this area is poorly documented. To overcome the lack of information we mapped the area using a GeoSAR DEM and an Unmanned Aerial Vehicle based DEM. This paper presents two maps, a 1:25,000 scale map and a 1:5,000 detailed map of landforms along the Humadal Creek. Detailed categorization of landforms (at 1:5,000) allowed us to identify geomorphic processes in the village of Las Mesas and rural areas that triggered hazards for the communities. The morphologic evolution interpretation of this volcanic tropical area serves as a tool for future geohazard assessment in inhabited areas with important information gaps.@en

We present a transdisciplinary perspective for multiple actors interested in disaster-risk-reduction strategies in inhabited volcanoes, based on the novel approach of complexity and collaborative research. Our reflection is based on an ongoing research process that puts into dialogue scientific knowledge and local knowledge from Andean campesino communities inhabiting the Doña Juana Volcano-Páramo in the Latin American tropics. These local communities have experienced historically complex social, economic, and environmental conflicts in their territories; currently, most of them live in the buffer zones of the National Natural Park Doña Juana-Cascabel, which is part of Colombia’s national system of natural protected areas. We address inhabited Andean volcanoes as complex systems, which combine multi-temporal and spatial processes that allow for the emergence of nonlinear and heterogeneous social and ecological interdependencies. By transgressing disciplinary boundaries, we see an opportunity for building horizontal dialogues with communities inhabiting active volcanoes, understanding resilience, and eventually developing situated and collaborative disaster-risk-reduction strategies. The resulting vision is proposed as a fundamental methodology in settings such as south-western Colombia, marked by convoluted social dwelling patterns, and unequal biosocial and socioeconomic histories. Detached from positivistic and victimising perspectives, we seek to build knowledge on the antecedents, inheritance, persistence, and preservation of systems, ultimately enabling response-abilities for decision-making. The motivations, knowledge, and self-organisation capacities of the volcano inhabitants bring about new possibilities of doing locally while thinking globally. The transdisciplinary research approach allows us to situate our exchanges with the local community, and envision future collaborative paths towards promoting community-oriented forms of appropriation and transformation of a volcanic lifeworld.

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Volcanic habitats host a dynamic environment for sudden and long-lasting relationships between nature and culture, becoming an archetypal case for the study of resilient communities. In these habitats, the study of the occurring phenomena is often addressed independently and in disciplinary isolation, focusing on the uncertainty and contingency of geohazards, the abrupt and recurrent resetting of biophysical conditions due to natural disturbances, or the intrinsic repercussions on the anthropogenic memory. Under this perspective, mass-movements within a volcanic habitat can be addressed as a complex system built over various generations of interacting and interdependent human societies, ecological systems, climate and geological processes. Understanding this multivariable and multi-scalar coexistence becomes central in how mass-movements are perceived. In this work, we propose a transdisciplinary approach for the formulation and design of alternative strategies in the mitigation of mass-movements hazards, by responsibly collaborating between geoscientists, social scientists, and local actors. Mass-movement mitigation strategies rarely take into account the cultural relationship of the inhabitants with their territories and the complexity of the local knowledge and capabilities of the communities to resolve their condition [2]. This limits the effectiveness in the response capacity and resilience of communities and ecosystems to extreme events [2]. Through this research, we aim at finding ways to democratize knowledge, and change academic practices within a geoethical context, recognizing and valuing the local perspectives. In this work, we study an area within the Doña Juana-Cascabel volcanic-complex, located in SW Colombia, and focus on the processes in the vicinity to the Humadal stream and neighbouring communities. This stream is recognized as the main preoccupation of the inhabitants with the recent occurrence of mass-movements in its basin. We address this issue through a team consisting of key local social actors and researchers in anthropology, archaeology, biology, design, engineering, geology, pedagogy, and pedology. We collaborate within a Historical Ecology framework, aiming to the empowerment of sociological resilience-based decision making [3]. This work started with the site recognition, mapping the geological, biological, and social settings. In parallel, we listened and valued the local knowledge about physical geography, ecosystems, and mass-movements in an active volcanic habitat, and merge it with the scientific knowledge. Moreover, this local knowledge enlighted key aspects on the interaction between the inhabitants and the State’s agencies and governmental processes, which underlay the dynamics of any reliable policy and sustainibile process. In this particular site, we identified the organizational capacity to work on reforestation, road maintenance, and weaving as fundamental capabilities for connecting with the design, potential implementation, and sustainability of a set of potential mitigation strategies. With this case study, we invite the multiple actors involved in disaster risk reduction to find common languages beyond disciplinary boundiaries aiming to horizontalize knowledge with the local actors in risk. Through this excercise, we avoid the victimization of the communities, reduce power relationships, and empower resilience.@en

On the night of March 31, 2017, a series of mass movements took place in the Mocoa Basin and devastated the northwestern part of its urban area. The mass movements were triggered by a 4-day rainfall accumulation and high rainfall intensities on the night of the event. After the trigger, about 420 mass movements transported material as landslides, debris flows, and hyperconcentrated flows along the Taruquita and Taruca creeks and Sangoyaco River on the northern side, and as landslides and mudflows along the Mulato River on its southern side, resulting in major damages to both its population and infrastructure. Previous reports by Cheng et al. (2018) and García-Delgado et al. (2019) described the event from a hydrological and geological perspective, connecting them with the damage caused by the event, but leaving aside an analysis of the series of mass movements and its characteristics. This work presents an extended review of these mass movements and studies them via a statistical analysis, providing a detailed review of the event’s characteristics and their relationship with the resultant damage. These characteristics are compared with the existing hazard maps and they provide valuable information and awareness on hazard management for communities settled in the northern Andes.@en