Boletin de Geologia最新文献

{"title":"Análisis de modelos de deslizamiento en bloque para predecir el comportamiento dinámico del fenómeno de remoción en masa: Modelo Uniparamétrico y Modelo Biparamétrico","authors":"Daniela Román, G. Chio","doi":"10.18273/REVBOL.V40N2-2018007","DOIUrl":"https://doi.org/10.18273/REVBOL.V40N2-2018007","url":null,"abstract":"espanolEn este estudio se presentan las variaciones conceptuales entre dos modelos de deslizamiento en bloque, cuya finalidad es determinar las propiedades cinematicas (alcance, velocidad y aceleracion) de una masa deslizante, y como afectan dichas variaciones conceptuales en la magnitud de la respuesta obtenida. Para ello se desarrollan y se solucionan tanto analitica como numericamente las ecuaciones de las variables que gobiernan el movimiento de cada uno de los modelos de deslizamiento, bajo la consideracion de que el movimiento se desarrolla en una sola dimension, en un material isotropico y en funcion de las variables independientes. En los modelos se consideran parametros como el angulo de friccion (φ), el parametro de turbulencia (ξ) y el coeficiente de presion de poros (ru). Finalmente se presenta la comparacion de las velocidades de ambos modelos y una seccion de comentarios en la que se discute la conveniencia del uso practico de cada solucion del problema de la dinamica de avalanchas. EnglishThis study aims to show the variations, from a conceptual perspective, between two sliding block models. The evaluation of these two models allows to determine the kinematic variables (range, velocity and acceleration) of a sliding mass. Herein, is assessed how the outcomes of these models are affected by varying the parameters of the friction angle (φ), turbulence (ξ), and pore pressure coeffiient (ru). To achieve this, the equations of motion are solved through analytical and numerical techniques assuming that, for an isotropic material, the motion is one dimensional and function of the independent variables. Finally, a comparison between the velocities obtained with each model is presented, and a concluding remarks section in which the practical use of each solution in the avalanche dynamics problem is argued.","PeriodicalId":44188,"journal":{"name":"Boletin de Geologia","volume":" ","pages":""},"PeriodicalIF":0.3,"publicationDate":"2018-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46172483","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"El sismo de Capellades del 2016 y su secuencia sísmica: Manifestación de fallamiento de rumbo en el arco volcánico de Costa Rica","authors":"Lepolt Linkimer, I. Arroyo, G. J. Soto, Juan L. Porras, M. C. Araya, Mauricio M. Mora, Magda Taylor","doi":"10.18273/revbol.v40n2-2018002","DOIUrl":"https://doi.org/10.18273/revbol.v40n2-2018002","url":null,"abstract":"espanolEl 30 de noviembre del 2016 a las 18:25 (00:25 UTC del 1 de diciembre) ocurrio un sismo de Mw 5,5 a una profundidad de 2,7 km, 4 km al norte de Capellades de Alvarado, Costa Rica. Fue el evento principal de una secuencia con precursores y replicas, localizada a 5 km de los volcanes activos Irazu y Turrialba. Este sismo es el mas reciente de una lista de terremotos originados en las fallas que cortan la Cordillera Volcanica Central, la cual representa el limite norte del area mas poblada del pais. Usando principalmente los registros instrumentales de la Red Sismologica Nacional (RSN), en este trabajo se presenta un analisis sismologico de la secuencia y se determinan la ubicacion y las caracteristicas de la falla que origino esta sismicidad. Adicionalmente, se describe el entorno geologico-tectonico de su origen y sus efectos. La secuencia de sismos muestra un claro alineamiento de 8 km de longitud y rumbo nor-noroeste, entre los volcanes Irazu y Turrialba. La interpretacion conjunta de la relocalizacion de la secuencia, el tensor de momento del sismo principal y los mecanismos focales de 17 eventos permitio determinar que la falla de origen es casi vertical y de tipo de desplazamiento de rumbo dextral, lo cual es congruente con los sistemas de fallamiento activo de la zona. Esta falla no habia sido reconocida previamente y se ha denominado Liebres en este estudio. El sismo principal fue sentido en casi todo el pais, con una intensidad maxima de VI+. Este sismo ha sido el de mayor magnitud en el sector oriental de la Cordillera Volcanica Central desde el terremoto de Patillos de 1952 (Ms 5,9) y el primer sismo de Mw > 5,0 registrado por la RSN en el edifiio volcanico del Turrialba. A pesar de la cercania con ese volcan, que ha presentado erupciones periodicas desde el 2010, no se observaron efectos eruptivos inmediatos. EnglishOn 30 November 2016 at 18:25 (1 st December at 00:25, UTC time) a Mw 5 5 earthquake occurred at 2.7 km depth, 4 km north of the town Capellades de Alvarado, Costa Rica. It was the main shock of an earthquake sequence including foreshocks and aftershocks, located 5 km from the active Irazu and Turrialba volcanoes. This is the most recent of a series of damaging earthquakes originated in the faults crossing the Central Volcanic Range, which constitutes the northern boundary of the most populated area of the country. Using mainly the seismic records from the National Seismological Network (RSN), we present in this study a seismological analysis of the earthquake sequence and the location and characteristics of the fault that originated this seismicity. Additionally, we describe the geotectonic context of the fault and the Capellades earthquake effects. The earthquake sequence shows a clear 8-km long alignment striking nor-northwest between Irazu and Turrialba volcanoes. The joint interpretation of the earthquake relocation, the main-shock moment tensor solution, and the focal mechanisms of 17 events allows for determinin","PeriodicalId":44188,"journal":{"name":"Boletin de Geologia","volume":" ","pages":""},"PeriodicalIF":0.3,"publicationDate":"2018-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47412903","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Tomografía sísmica 3D del nido sísmico de Bucaramanga (Colombia)","authors":"Francia Jullyette Sepúlveda-Jaimes, Francisco Henry Cabrera-Zambrano","doi":"10.18273/REVBOL.V40N2-2018001","DOIUrl":"https://doi.org/10.18273/REVBOL.V40N2-2018001","url":null,"abstract":"","PeriodicalId":44188,"journal":{"name":"Boletin de Geologia","volume":" ","pages":""},"PeriodicalIF":0.3,"publicationDate":"2018-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43187771","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Estado isostático del abanico del rio Magdalena a partir de la interpretación de anomalías de campos potenciales, Cuenca Colombia","authors":"Luis Alejandro Garzón-Moreno, Orlando Hernández-Pardo","doi":"10.18273/REVBOL.V40N2-2018003","DOIUrl":"https://doi.org/10.18273/REVBOL.V40N2-2018003","url":null,"abstract":"The main purpose of this research is to clear up the isostatic state of the fan area of the Magdalena River from the interpretation of gravity and magnetic anomalies of the Colombia Basin in order to improve the theoretical knowledge on the geodynamic processes and the phenomenon of isostasy. Previous research suggests that the isostatic condition of the crust is strongly affected by the correlation between Free Air Gravity Anomalies (FAGA) and Terrain Gravity Effects (TGE). The analysis and interpretation include processing and mapping of gravity and magnetic anomalies. Correlations and interpretations of gravimetric anomalies confirm isostatic perturbations along the Colombian northwestern margin and the Colombia Basin. The validation of the results was done through the forward and inverse modeling from gravity and magnetic data and subsequent comparison with models of crust thickness from seismic data. The models suggest a low subduction angle and elastic deformation of the Caribbean plate, which is affected by the sedimentary load of the paleo-delta of the Magdalena River, the geo-tectonic provinces of the Sinú-San Jacinto belt and the continental crust.","PeriodicalId":44188,"journal":{"name":"Boletin de Geologia","volume":" ","pages":""},"PeriodicalIF":0.3,"publicationDate":"2018-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45515566","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cálculo de las propiedades geotécnicas a partir de las velocidades transversales obtenidas en la sísmica de refracción. Estudio de caso en la ciudad de Luanda (Angola)","authors":"Maria Amélia Pereira de Barros da Silva, H. Fernández, João Júnior Baptista, G. J. P. Teixeira-Pires","doi":"10.18273/REVBOL.V40N2-2018006","DOIUrl":"https://doi.org/10.18273/REVBOL.V40N2-2018006","url":null,"abstract":"espanolLa sismica de refraccion es un metodo de geofisica de prospeccion, que estudia las respuestas del terreno cuando se propaga a traves de el una onda de compresion (onda P) producida por medios mecanicos en la superficie. El parametro fisico que se utiliza es la velocidad de propagacion de la onda Vp que viaja a traves de los materiales del subsuelo en funcion de la densidad del mismo. Tal parametro aportara informacion de las caracteristicas geomecanicas de la zona en la que se aplican. Los indices medidos mantienen correlaciones con la naturaleza geologica de los diversos horizontes, pudiendose aun conocer sus respectivas profundidades y espesores. Este trabajo tiene como objectivo presentar un procedimiento para la representacion de los parametros geotecnicos, estimados por el metodo de refraccion sismica. Las velocidades longitudinales son obtenidas y se correlacionan con los valores de la resistencia a la penetracion estandar (N) calculados por los ensayos homonimos de SPT. Los parametros dinamicos se presentan en secciones 2D para conseguir una mejor representacion e interpretacion, siendo capaz de caracterizar continuamente todo el area desde el punto de vista geotecnico. El area de estudio esta localizada en los suelos areno - limo - arcillosos de la ciudad de Luanda (Angola). EnglishSeismic refraction is a prospecting geophysical method, which measures the terrain response in reaction to a P compression wave, mechanically produced at the surface and propagating across. The physical parameter in use, in the case, is the wave propagation velocity, Vp, which travel across the subsurface rock material and reflcts to the surface in function of the material’s density it fids on its way down. That way, indexes associated to the parameter will measure and reveal the geomechanic characteristics of the terrain under study. Those indexes, whilst keeping some correlations with the geological nature of the rock in different horizons, allow to infer also their depths and thickness. The present study has the scope of showing a methodology to map geotechnical parameters using seismic reflction, and it has been noticed that the longitudinal velocities also computed are correlated with penetration resistance values, measured by Standard Penetration Tests (SPT). The dynamic parameters were chosen to be presented in 2D maps, in order to give either, a better representation of their characteristics, as well to allow for a continuous geotechnical interpretation over the entire area of study. The latter, is an area of silty/sandy soils located in the city of Luanda (Angola).","PeriodicalId":44188,"journal":{"name":"Boletin de Geologia","volume":" ","pages":""},"PeriodicalIF":0.3,"publicationDate":"2018-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45388650","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Basaltos de San Pablo: un bloque de un arco de islas en el norte de la cordillera Central de Colombia. Caracterización petrográfica y química","authors":"G. Rodríguez-García, Carlos Mario Celada-Arango","doi":"10.18273/REVBOL.V40N2-2018004","DOIUrl":"https://doi.org/10.18273/REVBOL.V40N2-2018004","url":null,"abstract":"The San Pablo Basalts constitute an exotic block of volcanic rocks that crop out next to marine sediments, located in the Northern part of Colombia ́s Central Cordillera, between metamorphic blocks of the Cajamarca Complex and intruded by the Antioquia Batholith, Upper Cretaceous in age. The San Pablo Basalts are composed of basalts (spilitic diabases), with intergranular to phiticsubophitic and occasionally porphyritic and variolitic-subophitic textures, similar to the oceanic crust rocks of the Quebradagrande Complex and the San Jose de Urama Diabases. The higher oxides results suggest that the rocks correspond to calc-alkaline, basalts and basaltic andesites, with SiO2 contents between 43.13% and 55.36%, MgO concentration ranges between 5.85% and 9.45% and TiO2 values between 1% and 2%. Multi-element diagrams of rare earth elements and trace elements show a negative Nb anomaly and positive anomalies of Cs, Ba, K and Pb, which suggests an arc environment with an REE trend similar to MORB-type oceanic crust basalts in the less differentiated rocks, but with higher Th values, which relates them to an island arc environment.","PeriodicalId":44188,"journal":{"name":"Boletin de Geologia","volume":" ","pages":""},"PeriodicalIF":0.3,"publicationDate":"2018-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49326655","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"INVERSIÓN SÍSMICA POR ALGORITMO GENÉTICO CON MIGRACIÓN DE POBLACIONES PARA ESTIMAR ANISOTROPÍA HTI","authors":"Juan J. Tovar, O. Almanza, Luis Montes-Vides","doi":"10.18273/REVBOL.V38N4-201600","DOIUrl":"https://doi.org/10.18273/REVBOL.V38N4-201600","url":null,"abstract":"Se implementó un algoritmo genético en MATLAB para realizar inversión sísmica y determinar anisotropía HTI, el cual se aplicó a un proyecto sísmico en la cuenca del Valle Medio del Magdalena en Colombia. El algoritmo que incluye el concepto de migración de poblaciones (MP), fue probado en condición de isotropía (paralelo a las fracturas) y anisotropía (perpendicular a las fracturas), mostrando mejor desempeño en la fase de prueba con datos reales. Se determinó la presencia de anisotropía débil en la zona de estudio con asociación a fracturas con acimut de 45°, perpendicular al régimen de esfuerzo actual en la zona, lo que explicaría la anisotropía débil relacionada con fracturas asociado a un régimen de paleo-esfuerzos.","PeriodicalId":44188,"journal":{"name":"Boletin de Geologia","volume":"13 1","pages":""},"PeriodicalIF":0.3,"publicationDate":"2016-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67949159","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}