Evaluación de susceptibilidad y peligro de remociones en masa en el sector costero de Reñaca, Viña del Mar, Chile
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2020
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es
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Universidad Andrés Bello
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Licencia CC
Licencia CC
Resumen
El presente trabajo consiste en el análisis de peligro de remociones en masa en la zona costera de Reñaca, Viña del Mar, aplicando las metodologías de Muñoz (2013) y Lara (2007).
Reñaca se ubica en las planicies litorales ubicadas al norte de la comuna de Viña del Mar, región de Valparaíso. Esta zona se caracteriza por su alta actividad estival y los altos niveles de urbanización, como también por poseer parte de las vías del sistema metropolitano de transportes de Valparaíso.
La geología del área es compuesta por un basamento ígneo denominado Unidad Cochoa, la que sirve de base para depósitos eólicos inactivos, litorales y aluviales. En las cercanías del área se encuentra la Zona de falla Marga Marga, la que registra importantes daños a la ciudad a través de su historia sísmica.
Las metodologías utilizadas corresponden a las desarrolladas por Muñoz (2013) y Lara (2007), las que evalúan índice de susceptibilidad y peligro de remociones en masa, respectivamente. La primera de ellas utiliza la ponderación de factores condicionantes de acuerdo con su influencia en la ocurrencia de los eventos. La segunda, se basa en el análisis cuantitativo, probabilístico y cualitativos de estabilidad de ladera y el análisis de alcance para cada remoción estudiada. Los análisis se realizan bajo diferentes escenarios climáticos, sísmicos y estáticos, tomando en cuenta el contexto climático y geográfico donde se encuentra el área de estudios. Estos escenarios representan los probables agentes desencadenantes de los eventos de remoción en masa.
Los avances tecnológicos permiten realizar estudios con menor costo económico y mayor rapidez con el paso del tiempo. Los vehículos aéreos no tripulados o “drones” son un avance significativo para los estudios geomorfológicos a pequeña escala comparado con los modelos satelitales. Para el caso de este estudio, se utilizó un dron Mavic pro 2 para realizar una fotogrametría que permitiera un análisis topográfico y geomorfológico en detalle de parte del área de estudios.
Los resultados de susceptibilidad muestran que la zona de estudios es susceptible a fenómenos de remoción en masa del tipo deslizamientos rotacionales y superficiales de suelo, y en menor grado a deslizamientos y caídas de roca.
Los análisis de peligro de remociones en masa muestran que la zona presenta mayormente peligro de deslizamientos de suelo en la zona norte de Reñaca y afloramientos artificiales locales de alta pendiente. Estos afloramientos puntuales también presentan un alto grado de peligro asociado a caídas de roca y deslizamientos en bloque.
The present work constrains a landslide hazard analysis of the coastal zone of Reñaca, Viña del Mar, by applying the methodologies developed by Muñoz (2013) and Lara (2007). Reñaca is situated on top of the coastal planes to the north of Viña del Mar city, Valparaiso Region. This zone is frequently characterized for its high summery activity and urbanization levels, as well as for hosting part of the metropolitan transport system routes of Valparaiso. Geology of the area consists of inactive coastal and aeolian and alluvial sediments, uncomfortably deposited on top of an igneous basement denominated as Unidad Cochoa. Marga – Marga Fault Zone is also located in the near proximity of the area, showing important records of damage to the city across of its active seismic history. The methodologies used in this work correspond to those developed by Muñoz (2013) and Lara (2007), which evaluate susceptibility index and landslide hazards, respectively. The first one utilizes conditioning factor weighing according to their influence in event occurrence. The later is based on a quantitative, qualitative, and probabilistic analysis of slope stability plus the analysis scope for each landslide studied. The analyses are done under different climatic, seismic, and static scenarios. These represent the more probable triggering agents for landslide events. Over time, technological advances are allowing more quick and low cost-wise analyses. Unmanned aerial vehicles or “drones” have shown a significant progress for small-scale geomorphologic studies in comparison with satellite obtained data. In the case of this study, a Mavic Pro 2 drone was used for obtaining photogrammetry data of a particular zone, which was later used to develop a in-detail topographic and geomorphological analysis. Results of susceptibility show that the area constrained in this study is susceptible to landslide phenomena, particularly of rotational- and surface-sliding type and of sliding rock fall events to a lesser degree. Hazard analyses of mass wasting also show that the higher surface-sliding hazard zone is located on the north zone of Reñaca and on the local artificial outcrops of high slope angle. These particular outcrops also show a high hazard level associated to rock fall and block sliding events.
The present work constrains a landslide hazard analysis of the coastal zone of Reñaca, Viña del Mar, by applying the methodologies developed by Muñoz (2013) and Lara (2007). Reñaca is situated on top of the coastal planes to the north of Viña del Mar city, Valparaiso Region. This zone is frequently characterized for its high summery activity and urbanization levels, as well as for hosting part of the metropolitan transport system routes of Valparaiso. Geology of the area consists of inactive coastal and aeolian and alluvial sediments, uncomfortably deposited on top of an igneous basement denominated as Unidad Cochoa. Marga – Marga Fault Zone is also located in the near proximity of the area, showing important records of damage to the city across of its active seismic history. The methodologies used in this work correspond to those developed by Muñoz (2013) and Lara (2007), which evaluate susceptibility index and landslide hazards, respectively. The first one utilizes conditioning factor weighing according to their influence in event occurrence. The later is based on a quantitative, qualitative, and probabilistic analysis of slope stability plus the analysis scope for each landslide studied. The analyses are done under different climatic, seismic, and static scenarios. These represent the more probable triggering agents for landslide events. Over time, technological advances are allowing more quick and low cost-wise analyses. Unmanned aerial vehicles or “drones” have shown a significant progress for small-scale geomorphologic studies in comparison with satellite obtained data. In the case of this study, a Mavic Pro 2 drone was used for obtaining photogrammetry data of a particular zone, which was later used to develop a in-detail topographic and geomorphological analysis. Results of susceptibility show that the area constrained in this study is susceptible to landslide phenomena, particularly of rotational- and surface-sliding type and of sliding rock fall events to a lesser degree. Hazard analyses of mass wasting also show that the higher surface-sliding hazard zone is located on the north zone of Reñaca and on the local artificial outcrops of high slope angle. These particular outcrops also show a high hazard level associated to rock fall and block sliding events.
Notas
Memoria (Geólogo)
Palabras clave
Remociones en Masa, Riesgo Geológico, Evaluación, Chile, Reñaca