Browsing by Autor "Miguel Cabrera"

Now showing 1 - 3 of 3

A transdisciplinary approach to mass-movements mitigation strategies in volcanic habitats: an approach from complex systems
(2020) Natalia Pardo; Miguel Cabrera; Catalina González; Mónica Espinosa; Ricardo Camacho; Nancy Palacios Mena; Susana Salazar; Leonardo Parra; Sonia Archila
&lt;p&gt;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.&lt;br&gt;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 Do&amp;#241;a 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&amp;#8217;s agencies and governmental processes, which underlay the dynamics of any reliable policy and sustainibile process.&amp;#160;&lt;br&gt;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.&lt;/p&gt;&lt;p&gt;[1]Martin, Martin &amp; Kent, (2009). Journal of environmental management, 91(2), 489-498.&lt;br&gt;[2]Gaillard, (2008). Journal of volcanology and geothermal research, 172(3-4), 315-328.&lt;br&gt;[3]Brierley, (2010). &amp;#160;Area, 42(1), 76-85.&lt;/p&gt;
Internal kinematics in a planar granular column collapse
(2020) Miguel Cabrera; Gustavo Pinzón
&lt;p&gt;The granular column collapse is a simplified system of the complex dynamics observed in gravity-driven natural mass-movements (i.e., landslides, debris flows, rock avalanches) and industrial applications (i.e., pharmaceutics, concrete, and food industry). In this system, a granular column is built with an initial height and initial width and then is allowed to collapse by self-weight onto a horizontal plane, while observing the variation in runout as a function of its initial geometry. Despite its wide use in the study of mass-movements mobility, either dry or with a liquid, little is known on the internal physics during collapse and its variation when immersed in an ambient fluid. This work presents a planar setup that allows the study of fully and partially immersed granular columns, with little disturbance at release [1]. The use of a planar configuration allows the monitoring of the moving mass and its deformation patterns, providing a unique insight into the particle-fluid interactions at release and during collapse that were not possible before. These observations are of great importance for the understanding of particle-fluid interactions at a mesoscale and can shed light into larger processes like a submarine and subaerial landslides. This work addresses these interactions by varying the geometry and measuring the mobility in dry and immersed conditions. The associated deformation patterns are observed both at the column-scale and at the particle-scale, reflecting in the velocity scaling of a deformable and moving granular mass and the occasional ejection of particles at its surface. We observed that the area of the released portion decreases during collapse and converges toward an equivalent portion of surface particles with little influence by the initial column geometry. These observations validate the planar setup for the study of granular columns, provides a novel interpretation in the momentum transfer in particle-fluid systems, and sets a validation case for future numerical simulations.&lt;/p&gt;&lt;p&gt;[1] Pinzon &amp; Cabrera, Planar collapse of a submerged granular column. Physics of fluids, v31, 2019.&lt;/p&gt;
Monodisperse behavior of polydisperse flows
(American Physical Society, 2025) Oscar Polanía; Mathieu Renouf; Miguel Cabrera; Nicolás Estrada; Émilien Azéma
Granular flows can occur under low inertia conditions, called the quasi-static regime, and extend to highly inertial systems, called the inertial regime. In the latter, granular flows, particularly those having a variety of grain sizes-property known as polydispersity-have not been extensively studied. Existing rheological laws for monodisperse flows effectively capture volume and friction variations across inertial ranges, assuming the grains diameter as the flow characteristic length. For polydisperse materials, this assumption is less intuitive, and rheological laws cannot be extended straightforwardly. In this work, we employed the Discrete Element Method to study granular flows across varying inertial levels, aiming to identify a physically based length scale that represents the grain scale for polydisperse flows. We show that the average branch length (i.e., distance between the centers of contacting grains) is a representative value of the material's grain size distribution, remaining nearly constant across the explored range of inertia. Moreover, we show that monodisperse and polydisperse flows follow common inertial volume and friction laws when the average branch length is considered as the characteristic length. The findings of this work propose a new perspective for understanding the characteristic length of granular flows, providing a comprehensive interpretation based on the grains contacts. They also permit to extend rheological laws, initially proposed for monodisperse flows, to polydisperse flows by considering the characteristic length scale as the average branch length. Finally, Our results are useful for choosing the characteristic length that controls large-scale flows where polydispersity plays an important role.