A numerical model for the dynamics of pyroclastic flows at Galeras volcano, Colombia

This paper presents a two-dimensional model for dilute pyroclastics flow dynamics that uses the compressible Navier - Stokes equation coupled with the Diffusion - Convection equation to take into account sedimentation. The model is applied to one of the slopes of Galeras Volcano to show: (1) the temperature evolution with the time; (2) dynamic pressure change; and (3) particle concentration along the computer domain from the eruption to the impact with a topographic barrier located more than 16 km from the source. Two initial solid volumetric fractions are modeled. For both cases, some of the structures located more distant than 10 km could survive, but in all cases the flow remains deadly. This paper shows that a dymanical model of pyroclastics flows can be implemented using personal computers

Residents, decision makers, and scientists discuss volcanic hazard in Colombia

Abstract Galeras volcano, located in southwestern Colombia, imposes several hazards on the surrounding population: pyroclastic flows, lahars, ashfall, and shock waves. The current hazard map shows three zones: high, medium, and low (see A. D. Hurtado Artunduaga and G. P. Cortés Jiménez, J. Volcanol. Geotherm. Res., 77, 89–100, 1997). The pyroclastic flow hazard on this map defines the Zone of High Volcanic Hazard (ZAVA) for civil authorities. Current activity of Galeras has provoked two contentious issues related to hazard management: (1) Decision makers announce an evacuation order of ZAVA whenever the volcanic alert reaches a high level, and (2) the Colombian government initiated a relocation program for the inhabitants within ZAVA (Colombian Decrees-Laws 4106 and 3905). However, communities within ZAVA refuse to obey both the evacuation orders and the relocation process. To help resolve this situation, the University of Nariño (Colombia) and the State University of New York at Buffalo organized a workshop, which was sponsored by the U.S. National Science Foundation. A daily average of 92 people attended, including residents of ZAVA, decision makers, Colombian technical and scientific personnel, international scientists and researchers, students, and academics from the University of Nariñ

Aportes para una reconstrucción lógica de categorías kuhnianas

En la presente comunicación, abordo el análisis de esta interpretación lógica de la posición kuhniana y como resultado pretendo establecer que el conjunto de categorías que Kuhn propone puede ser reconstruido como un sistema

Árboles de Navidad: Estado de la Reforestación en Costa Rica

Proyecto de Investigación. Instituto Tecnológico de Costa Rica . Escuela de Ingeniería Forestal, 2012The cultivation of Christmas trees practiced in Costa Rica is unique in its style in Tropical America, because this has been based on the exclusive use of cypress (Cupressus lusitanica) in a ratio of supply and demand and negligible positive for producers. This type of reforestation is unique in that trees receive special care from the time of planting to harvest, making intensive character. But the forestry sector has actual and accurate documentation of the geographical location of these plantations, as well as techniques or practices used by farmers in reforestation, and also on issues related to its marketing and commercialization. This activity strengthening research main objective was to assess the state of the Christmas tree reforestation in Costa Rica. This type of reforestation has a potential close to a crash as long as aspects outweigh line aimed at ensuring better forest management silvicultural technical assistance. The experience of the producer, the existence of a technology package and a tradition by the user are opportunities that favor this practice in our country.Instituto Tecnológico de Costa Ric

TITAN2F: a pseudo 3D model if 2-phase debris flows

Debris flows, avalanches, landslides, and other geophysical mass flows can contain O(106–1010) m3 or more of material. These flows commonly consist of mixture of soil and rocks with a significant quantity of interstitial fluid. They can be tens of meters deep, and their runouts can extend many kilometers. The complicated rheology of such a mixture challenges every constitutive model that can reasonably be applied; the range of length and timescales involved in such mass flows challenges the computational capabilities of existing systems.This paper extends recent efforts to develop a depth averaged "thin layer" model for geophysical mass flows that contain a mixture of solid material and fluid. Concepts from the engineering community are integrated with phenomenological findings in geo-science, resulting in a theory that accounts for the principal solid and fluid forces as well as interactions between the phases, across a wide range of solid volume fraction. A principal contribution here is to present drag and phase interaction terms that comport with the literature in geo-sciences. The program predicts the evolution of the concentration and dynamic pressure. The theory is validated with with data from one dimensional dam break solutions and it is verified with data from artificial channel experiments

Effects of the concentration of solids on the phenomenon of super-elevation in artificial curved open channels

This present study analyses the effects of the concentration of solids in the over-elevation phenomenon in a canalwith a 180° curvature and a constant trapezoidal transversal section, with a firm bed, the fluid has a non-colloidal,mono-disperse distribution of relatively spherical particles of 1mm in size, thus making the rheology of the flow de-scribable by the Einstein-Roscoe equation (1). Two stages are proposed for the development of the research; the firstcorresponds to physical experimentation, achieved using an artificial canal, in which 420 tests were carried out usingdifferent concentration of solids and two slopes, in order to determine the behaviour of the bi-phased flow. All of thisis carried out by using experimental results and results obtained from numerical models. The data collected from theexperimental process is compared to the results obtained from the theoretical models that are reported in literature.An over-elevation equation was formulated from the analysis, which can be used for the bi-phased conditions de-scribed in this article. During the second phase, numerical modelling using the TITAN2F software was carried out,where laboratory conditions are replicated. Data found from numerical modelling is compared with experimentalresults, with the intention of validating the numerical model that TITAN2F uses. From what is mentioned above, itwas deduced that TITAN2F effectively reproduces the hydraulic phenomenon. However, it is also observed that theprogram has a low susceptibility to changes in the concentration of solids, due to the scale being use

Evaluación probabilística del peligro por lahares en el flanco NE del Volcán Popocatépetl

This study shows the results of a probabilistic evaluation of laharic hazard to Santiago Xalitzintla, locality in Puebla, at the NE flank of the Popocatépetl volcano in México. The TITAN2F software was used for lahars modeling. The program forecasts were compared with data obtained in the field for the laharic event of 2001 in order to evaluate the reliability of its use on a digital elevation model. The results obtained with TITAN2F are comparable with information reported previously in other studies of this lahar; coming to the conclusion that modeling with TITAN2F is reliable. This investigation provides a useful tool for the knowledge of laharic hazards. Also, it shows the probability of the affected area by inundation as well as the probability distribution of dynamic-pressure levels, which is an important parameter for assessment risk in a lahar flow. To make a probabilistic analysis is required a number of statistically representative hypothetic scenarios, covering all possible cases. According to historical events recorded, two possible sources for a laharic flow were defined, and they correspond to the Huiloac and Alseseca gorges. Based on the geological information, the ranges of initial conditions that TITAN2F requires (velocity, concentration and volume) were defined for each one of the basins. A stratified sampling was carried out using the Latin Hypercube method (LHS). This method generates a representative sample of hundreds of combinations from the initial conditions, in order to modeling laharic events with TITAN2F. The probabilistic analysis was made through Bayesian inference, and programming routines in OCTAVE. The probabilistic distribution indicates that there is a nearly 80 % probability to be reached by lahars at community areas of Santiago Xalitzintla. However it is characterized by low dynamic-pressure levels. The final section of the Huiloac gorge was identified as a critical zone, where the probability that dynamic-pressures surpassing destructive levels is high

TITAN2F

El programa de computo para el modelamiento de flujos bifasicos de gravedad, desarrollado con el apoyo de la national science foundation (grant NSF- EAR 711497), simula flujos de gravedad Bi-fasicos consistentes en una mezcla de agua y solidos. El programa se basa en un modelo de profundidad promedio para medio continuo en el cual se cumplen las leyes de Darcy-Wisbach para la fase liquida y la de Coulomb para la fase solida

Congreso de Ingeniería Civil aplicada al desarrollo rural

Coadyuvar en el desarrollo de la infraestructura de obras civiles locales, regionales y nacionales, a través de la formación de Ingenieros Civiles integrales, comprometidos, que se incorporen al mundo laboral y a la creación de empresas constructoras y consultoras, a través de la ciencia y la técnica, la investigación y la proyección social; que trabajen con dedicación y excelencia y con liderazgo empresarial para que contribuyan al desarrollo económico y social del país, al mejoramiento del sector urbano y rural, a la conservación del ambiente y al uso adecuado de los recursos naturales