Doctorado en Ciencias de la Tierra (tesis)

URI permanente para esta colección


Envíos recientes

Mostrando 1 - 8 de 8
  • Ítem
    Submarine landslides geohazard along the southern margin of the colombian caribbean : relation to ground conditions and effect on shaping seafloor geomorphology
    (Universidad EAFIT, 2023) Mateus Tarazona, Darwin Clemente; Prieto Salazar, Jorge Alonso
    Submarine landslides are a mixture of rock, soil, and fluids moving downslope due to a slope's initial event of mechanical failure. These phenomena play a significant role in the evolution of continental margins. On the one hand, sediment transport processes from the continental shelf to the foot of the continental slope are meaningful. On the other hand, submarine landslides play a critical role in shaping the geomorphology of the seafloor. In addition, they have the potential to affect coastal infrastructure, submarine telecommunications cables, and pipelines, and generate tsunamis and avalanches. Thus, the negative consequences of submarine landslides have been socially and economically significant. In the Colombian southern Caribbean margin, submarine landslides are closely related to regional tectonic dynamics and show distinctive characteristics in canyon walls, channel-levee systems, tectonically controlled ridges, and continental shelf break. Previous studies have highlighted the importance of landslides as geohazards analyzing the largest landslides observed in the bathymetry or studying their presence in limited areas of the Colombian southern Caribbean. This study shows a regional analysis of the occurrence of submarine landslides in the southern Colombian Caribbean. The geomorphological analysis was based on a bathymetric model that included seismic cubes and multibeam bathymetric surveys with resolutions ranging between 10 and 100 meters. These data involved areas from the continental shelf break to the foot of the continental rise making it easier to obtain a regional image of the seafloor in which the interpretation of landslide extended toward areas without 3D seismic information. After mapping the geographic distribution of submarine landslides, their relationship with ground conditions, including seafloor geomorphology, slope degree, fault presence, the Bottom Simulator Reflector (BSR), and Mass-Transport Complexes (MTCs), was analyzed. Finally, a preliminary map of landslides susceptibility was carried out following the landslide Weight index (Wi), a method proposed by Van Westen in 1997, and overpressure conditions in the sedimentary sequence were interpreted to see the relationship between both phenomena. Chapter 1. This chapter presents a detailed geomorphological mapping of submarine landslides carried out using a high-resolution 3D seismic survey. This mapping allowed obtaining a statistical analysis and a complete interpretation of geomorphological characteristics of the seafloor and subsoil patterns to define the morphology of landslides and their distribution of occurrence, and their relationship with structural deformation. Results suggest that landslides in the study area are related to thrust faults and structural ridges of the Southern Sinú Fold Belt (SSFB) that greatly contribute to the filling of intra-slope sub-basins isolated from the continental shelf. Chapter 2. This chapter shows the mapping of the southern Caribbean seafloor using seismic cube surveys and multibeam bathymetry data in an area encompassing 59,471 km2, which allowed analyzing the regional distribution of submarine landslides and simplifying their occurrence through the construction of a conceptual framework for a better insight. Distinctive characteristics were found for submarine landslides associated with canyon walls, channel-levee systems, tectonically controlled ridges, and continental shelf break. Also, can be observed that Mass-Transport Complexes (MTCs) result from the accumulation of mass movement originating both in the continental shelf break and the channel-levee systems. However, the size of MTCs does not represent individual events but rather the accumulation of multiple events. This fact made it possible to estimate a landslide susceptibility map which suggests the following considerations: Firstly, structural ridges and adjacent intra-slope sub-basins related to the South Caribbean Deformed Belt (SCDB) are more likely to be landslide hazards. Secondly, the continental shelf break and channelized systems produce a moderate landslide hazard potential. Thirdly, deep marine systems with a slope less than five degrees (<5°) show the lowest landslide hazard potential. Chapter 3. This chapter presents the analysis carried out on overpressures in the Sinú Offshore basin, summarizing the observations from well data, seismic data, and basin modeling. Overpressure zones were observed to match low velocities of sound from well logs and seismic cubes. Likewise, wells with the highest overpressures (>15 ppg) are located in the south of the study area, while wells located in the northern part of the basin showed lower overpressure conditions (<15 ppg). It is concluded that overpressures have a more direct relationship with anticlinal-type compression structures than with other geological phenomena, such as high sedimentation, which is certainly more related to landslides and Mass-Transport Complexes (MTCs) characteristic on the surface of the seafloor.
  • Ítem
    Quantitative geomorphology of the Northwestern Colombian Andes : contributions to landscape evolution and natural hazard assessment
    (Universidad EAFIT, 2023) Noriega Londoño, Santiago; Marín Cerón, María Isabel; Restrepo Moreno, Sergio Andrés
  • Ítem
    Caracterización del flujo hidrodinámico y evaluación de su impacto en la acumulación y producción de hidrocarburos en el sector sur de la Cuenca de Llanos, Colombia
    (Universidad EAFIT, 2022) Gómez Moncada, Ricardo Andrés; Jaramillo Uribe, Marcela; Mora Bohorquez, Andrés
    The southern sector of the Llanos Basin in Colombia has been identified as a basin where the hydrodynamic flow has influenced the potential of hydrocarbon storage and production. In this area the hydrodynamic flow coincides with a province of heavy and extra-heavy crude oils, which has hypothesized for this area, a critical condition that decreases the potential for hydrocarbon retention by the effect of hydrodynamic flow and the geochemical nature of the fluids. This work provides a comprehensive view to describe the impact of regional hydrodynamic flow on retention of the heavy oil accumulations present in the reservoirs that are part of the most important regional flow unit identified in the Southern Llanos Basin. The Basal Flow Unit (BFU) constitutes a basin-scale flow unit that hydraulically and laterally connects rocks from the Cretaceous (west) to the Oligocene (east) and extends from the basin's southwestern margin up to hundreds of kilometers within the Llanos foreland basin, and whose main water recharge zone has been identified towards the eastern flank of the Serranía de la Macarena. To understand the impact of the physicochemical properties of the fluids, we analyze the relationship between hydraulic data and the main characteristics of the fluids present in the BFU, and their spatial distribution on the present-day configuration of this flow unit. This analysis integrated information from hydraulic heads, SARA analysis (Saturates, Aromatics, Resins, and Asphaltenes), Whole Oil Gas Chromatography analysis, API-gravity, and oil densities. In addition, hydrochemical analysis of the primary ions and isotopic analysis (δ18O and δD) was performed in groundwater samples from the BFU, which was integrated with deep resistivity data measured in producing and exploratory oil wells in the area. The new isotopic analyzes of this study (δ18O and δD), and data from previous studies, allowed establishing the Local Meteoric Water Line (LMWL) for the Llanos basin. The δ18O and δD values of the groundwater samples follow the Local Meteoric Water Line proposed for the Llanos basin, supporting the presence of meteoric waters in the Basal Flow Unit and whose influence it extends from the recharge zone to more than 300 km east of the basin. The results allowed identifying the southwestern corner of the southern Llanos Basin as the area with the highest hydrodynamic flow impact, and therefore, the area with the least potential for hydrocarbon retention, attributing as the main causes: 1) the proximity to recharge areas, and 2) the low contrast of fluids densities (freshwaters and highly biodegraded heavy crude oils), implying high Tilt Amplification Factor (TAF) values. Furthermore, gradual changes in resistivities and ions concentration in groundwaters suggest the eastern flank of the Serranía de la Macarena as the main recharge zone of meteoric waters into the BFU. Finally, numerical simulation techniques were used to analyze the behavior of hydrocarbon drainage under hydrodynamic conditions, obtaining a first approximation to the average linear groundwater flow velocities between 10-3 and 10-4 ft/day.
  • Ítem
    Morphodynamics of deep-water gravitational deposits along a convergent tectonic margin : Southern Caribbean of Colombia
    (Universidad EAFIT, 2021) Naranjo Vesga, Julián Francisco; Paniagua Arroyave, Juan Felipe; Ortiz Karpf, Andrea Lucía
  • Ítem
    Analysis of the environmental licensing procedure for coastal environments in Colombia : a geomorphological perspective from the concept of susceptibility to the effect of human interventions
    (Universidad EAFIT, 2019) Pereira Pomárico, Cristina Isabel; Correa Arango, Iván Darío
    Important flaws in the environmental licensing procedures in Colombia are directly related to the generalized degradation of its coastal fringes and littoral zones. These areas are severely affected by human interventions that interfere with natural processes and severely modify their sedimentary balances, geomorphological contexts, and physical-biotic conditions. Among many other examples, the following stand out: a) the widespread erosion and destruction of beaches and dunes in the Magdalena River delta, associated with the construction of the Bocas de Ceniza jetties; b) the drastic modification of the hydrodynamics of the littorals at the Atlantic and Magdalena departments due to linear infrastructure projects; c) the hyper-salinization and loss of more than 30,000 hectares of mangrove in the lagoon complex of the Ciénaga Grande de Santa Marta (CGSM) due to the expansion of the agricultural frontier and linear infrastructure projects; d) the accelerated retreat of beaches and cliffs in the southern Caribbean, due to activities such as deforestation, beach material extraction, and disordered and chaotic construction of nearly 500 rigid shore protection works; and e) the salinization of more than 10,000 hectares of freshwater marshes in the Bay of Cispatá as a consequence of the induced formation of the new delta of Tinajones. In this sense, the location of infrastructure in geological and geomorphologically unstable lands, affected by phenomena such as coastal subsidence and mud diapirism, poses first order natural threats and risks. This is a palpable panorama in the present and future of urban and rural areas of cities such as Barranquilla, Cartagena, Arboletes and Necoclí, all of them with future developments (industry, ports, urban development) of the greatest importance. The environmental costs associated with such interventions are incalculable, not counting the existence of numerous other examples, which demonstrate among other factors an insufficient acknowledgment to geomorphology in the evaluation, monitoring, and control of human interventions in the marine-coastal environment. These environmental management functions in Colombia are provided through the environmental licensing procedure, which rests upon national and regional authorities according to Law 99 of 1993. In the above context, the following research questions arise:  What elements of the environmental licensing of interventions in coastal environments can be improved, giving priority to the particular geomorphological contexts of the intervention zones?  How has the regulatory system evolved in Colombia with respect to human interventions on coastal environments?  What technical improvements can be made to the Colombian regulatory framework to guide the evaluation, monitoring, and control of human interventions from the geomorphological approach of susceptibility? This research work examines the environmental regulatory framework that currently governs Colombian coastal zones, through two geographic levels. At the first macro level, human interventions 16 are characterized and analyzed on the continental Caribbean coast, a region that represents a significant sample of the Colombian context due to its higher levels of human occupation and consequent anthropogenic disturbances. At a second level, in greater detail, the conceptual and methodological approach resulting from this research is defined and illustrated, with the demonstration in one of the coastal environmental units defined by decree 1120 of 2013 for integrated coastal management. To answer the questions raised, Chapter I briefly introduces the historical geomorphological evolution of the Colombian coastlines since the end of the XVIII century. The complex geology and geomorphology of the Caribbean and Pacific coasts of Colombia are evident in this "appetizer", in which low-relief deltaic islands and mangroves contrast with steep rocky reliefs, cliffs and wide emerged and submerged coastal platforms. The historical evolution of the Colombian littorals involves changes in the coastline estimated in hundreds of meters, at maximum rates of 40 meters a year (Punta Rey, Arboletes, Tumaco Bay), and land losses and gains of the order of tens of square kilometers (Ciénaga de Mallorquín, Isla Cascajo, Tinajorenas Delta - Cispatá, Bay, Urabá Gulf, San Juan and Patía river deltas). These cases reflect drastic variations in the sediment balances of the coast, many of them caused or heavily influenced by human actions, such as navigation infrastructure, modification of river courses and coastal protection works. Chapter II identifies the geomorphological perspective in the environmental licensing of coastal interventions in Colombia, based on its comparison with the regulatory frameworks of Italy, Spain, and Cuba. The interviews and documentary reviews highlighted 59 interventions associated with human uses and activities in the coastal zones, whose compulsory nature for the licensing varies among countries. The natural geomorphological processes were also analyzed within the technical criteria included in the official guidelines for environmental studies. It is concluded that, despite the worldwide acceptance of environmental impact assessments through a licensing procedure, their application in coastal environments is still very diverse and limited in terms of the pertinence of the geomorphological processes that configures the coast. Therefore, seven good practices for the evaluation and control of anthropogenic impacts in the coastal zone are underlined, and a new process-oriented approach is introduced for environmental licensing procedures. In Chapter III, an inventory and characterization of human interventions on the continental coast of the Colombian Caribbean are documented, to establish a regional baseline. Based on images from Google Earth, a total of 2,742 works and activities were located, representing 29 different types of human interventions. This inventory was complemented with an evaluation of the general impact of each intervention, based on four attributes of its geomorphological effects, namely, extension, intensity, reversibility, and persistence. The three most common types of human interventions (low-density settlements, groins and luxury settlements with dock) were also the ones with the higher environmental impact. However, some interventions (e.g., high-density settlements or road infrastructure) had higher environmental impact values than more frequent ones. 17 Based on this exhaustive analysis of the Colombian Caribbean, Chapter IV evaluates the national environmental regulatory framework applicable to coastal areas. It evidences that the licensing procedure in Colombia currently regulates only four of the ten types of interventions with greater effect in the Colombian coastal zones. Also, the number of works and activities covered in each new legislative reform consistently decreased over time. In addition, three policy implications were extracted for coastal and ocean planning, related to a) the geographic diversity of tropical coastal zones; b) the need for territorial carrying capacity instruments and; c) the lack of articulation of territorial planning instruments. The conclusions identify an important gap between technical and political decision making in the environmental regulatory framework of Colombia, which stresses the need for the design of novel methods to assess the breadth and length of geomorphological dynamics in an environmental management context. Therefore, the previous chapters highlight three important deficiencies in Colombia, with respect to the environmental management of human interventions in coastal areas: 1) the absence of a strategy to determine interventions that require an environmental licensing procedure (screening); 2) a poor definition of the scope of environmental studies through relevant information requirements (scoping) and; 3) the disarticulation of environmental management instruments, such as territorial planning and environmental licenses. All these elements ratify that the environmental regulatory framework in Colombia has been insufficient to date to manage the anthropogenic impact in coastal environments due to the unawareness of the natural susceptibility to the effect of human interventions. In this work, the susceptibility is defined as the predisposition of an environmental unit (socio-natural system) to experience changes or affectation due to the introduction of human interventions. In order to propose improvements to the Colombian environmental system, Chapter V establishes a new conceptual and methodological approach to guide the evaluation, monitoring, and control of human impacts from a geomorphological perspective. This novel product has been called Susceptibility to Human Interventions for Environmental Licensing Purposes (SHIELP). The architecture of this model has three components, which are particular to a kind of environment, namely, geomorphological processes, geomorphological configurations and potentially impacting human interventions. Each of these components is translated into a variable by means of expert qualifications along with a fuzzy logic computation strategy. Therefore, the expert-diffuse system SHIELP qualifies the susceptibility of a distinctive landform to the effects of a characteristic type of human intervention, through the estimated perturbation in each geomorphological process that configures the kind of environment under study. As a demonstration, this chapter also documents the design of the expert-diffuse system for coastal environments, drafted from research workshops with members of the marine and coastal research institute INVEMAR (In Spanish: Instituto de Investigaciones Marinas y Costeras “José Benito Vives de Andréis”). The role of this institute as an official adviser to the environmental authorities in matters of impact assessment demonstrates its relevance to support the expert-knowledge base of the model. 18 As a consequence, the SHIELP model was applied with the parameters established for coastal environments, resulting in a database of susceptibility values for 4,524 interactions (littoral configuration vs intervention). The real applicability of this exercise corresponds to the translation of this database into a technical criterion to improve the Colombian regulatory framework. On the one hand, five susceptibility ranges were linked to five differentiated instruments, two of which articulate environmental licensing with territorial plans, while the others differentiate the pertinent degree of licensing for human interventions according to location properties (screening). On the other hand, the differentiated instruments were also combined with four degrees of information requirements for the definition of the scope in the respective environmental studies (scoping). In this way, the susceptibility value of a given intervention in a given configuration (interaction) would fit a percentile range that places its environmental control in a territorial competence (regional or national), and through a specific licensing instrument, with differentiated information requirements for the baseline definition. Finally, the operation of the SHIELP model was also demonstrated with a case study: the environmental coastal unit Magdalena River - Canal del Dique complex - Ciénaga Grande de Santa Marta lagoon system. The geographic information of this regional coastal unit was interpreted according to the parameters defined in the SHIELP model for coastal environments. 154 polygons were delimited in the study area, according to the 40 coastal configurations identified. As a result, 13 cartographic maps represent this area, with the levels of susceptibility attributed to each configuration for the 52 potentially impacting interventions. In order to illustrate the applicability of the model, four scenarios are presented to discriminate interventions by environmental management instrument (screening) and to define information requirements on geomorphological processes (scoping). In this way, the SHIELP model specifies the environmental licensing instrument for human interventions and the corresponding scope of the technical study, given the characteristics of its interaction with the geomorphological configuration. The Overall Conclusions document reflections and recommendations to the Colombian national environmental system – SINA (in Spanish: Sistema Nacional Ambiental) to implement the results of this research. In addition, this work opens a broad perspective for future research in the approach of susceptibility to the effect of human interventions. The SHIELP model for coastal environments can be replicated in different geographies to progressively articulate a national database of coastal susceptibility. Also, the presented methodological scheme can be applied in different kinds of environments, other than the coastal zone. The extension of this approach of geomorphological susceptibility to the variety of tropical ecosystems would set the path for a successful transition from the current anthropocentric and fragmentation-oriented conception towards an ecosystem-based management approach.
Todo persona que consulte en este repositorio podrá copiar apartes del texto citando siempre la fuentes, es decir el título del trabajo y el autor. Esta autorización no implica la renuncia a la facultad que tiene el autor de publicar total o parcialmente la obra.
La Universidad no será responsable de ninguna reclamación que pudiera surgir de terceros que invoquen autoría de la obra que presenta el autor.
Todos los derechos reservados.