Time filter

Source Type

Quito, Ecuador

The National Polytechnic School , also known as EPN, is a public university located in Quito, Ecuador.EPN is known for research and education in the applied science, astronomy, atmospheric physics, engineering and physical science. The Geophysics Institute monitors over the country`s seismic, tectonic and volcanic activity in the continental territory and in the Galápagos Islands.EPN adopted the polytechnic university model that stresses laboratory instruction in applied science and engineering.One of the oldest observatories in South America is the Quito Astronomical Observatory. Founded in 1873 and located 12 minutes south of the Equator in Quito, Ecuador. The Quito Astronomical Observatory is the National Observatory of Ecuador and is located in the Historic Center of Quito and is managed by the National Polytechnic School. Wikipedia.

Chiaradia M.,University of Geneva | Muntener O.,University of Lausanne | Beate B.,National Polytechnic School of Ecuador
Journal of Petrology | Year: 2011

The origin of andesite is an important issue in petrology because andesite is the main eruptive product at convergent margins, corresponds to the average crustal composition and is often associated with major Cu-Au mineralization. In this study we present petrographic, mineralogical, geochemical and isotopic data for basaltic andesites of the latest Pleistocene Pilavo volcano, one of the most frontal volcanoes of the Ecuadorian Quaternary arc, situated upon thick (30-50 km) mafic crust composed of accreted Cretaceous oceanic plateau rocks and overlying mafic to intermediate Late Cretaceous-Late Tertiary magmatic arcs. The Pilavo rocks are basaltic andesites (54-57·5 wt % SiO. 2) with a tholeiitic affinity as opposed to the typical calc-alkaline high-silica andesites and dacites (SiO. 2 59-66 wt %) of other frontal arc volcanoes of Ecuador (e.g. Pichincha, Pululahua). They have much higher incompatible element contents (e.g. Sr 650-1350 ppm, Ba 650-1800 ppm, Zr 100-225 ppm, Th 5-25 ppm, La 15-65 ppm) and Th/La ratios (0·28-0·36) than Pichincha and Pululahua, and more primitive Sr (.87Sr/.86Sr ∼0·7038-0·7039) and Nd (e{open}. Nd ∼ +5·5 to +6·1) isotopic signatures. Pilavo andesites have geochemical affinities with modern and recent high-MgO andesites (e.g. low-silica adakites, Setouchi sanukites) and, especially, with Archean sanukitoids, for both of which incompatible element enrichments are believed to result from interactions of slab melts with peridotitic mantle. Petrographic, mineral chemistry, bulk-rock geochemical and isotopic data indicate that the Pilavo magmatic rocks have evolved through three main stages: (1) generation of a basaltic magma in the mantle wedge region by flux melting induced by slab-derived fluids (aqueous, supercritical or melts); (2) high-pressure differentiation of the basaltic melt (at the mantle-crust boundary or at lower crustal levels) through sustained fractionation of olivine and clinopyroxene, leading to hydrous, high-alumina basaltic andesite melts with a tholeiitic affinity, enriched in incompatible elements and strongly impoverished in Ni and Cr; (3) establishment of one or more mid-crustal magma storage reservoirs in which the magmas evolved through dominant amphibole and clinopyroxene (but no plagioclase) fractionation accompanied by assimilation of the modified plutonic roots of the arc and recharge by incoming batches of more primitive magma from depth. The latter process has resulted in strongly increasing incompatible element concentrations in the Pilavo basaltic andesites, coupled with slightly increasing crustal isotopic signatures and a shift towards a more calc-alkaline affinity. Our data show that, although ultimately originating from the slab, incompatible element abundances in arc andesites with primitive isotopic signatures can be significantly enhanced by intra-crustal processes within a thick juvenile mafic crust, thus providing an additional process for the generation of enriched andesites. © The Author 2011. Published by Oxford University Press. All rights reserved. Source

Torres L.M.,National Polytechnic School of Ecuador | Wagler A.K.,University Blaise Pascal
Mathematical Methods of Operations Research | Year: 2011

We present a model for the dynamics of discrete deterministic systems, based on an extension of the Petri nets framework. Our model relies on the definition of a priority relation between conflicting transitions, which is encoded by orienting the edges of a transition conflict graph. We provide a characterization in terms of a local consistency condition of those deterministic systems whose dynamic behavior can be encoded using our approach. Finally, we consider the problem of recognizing when an orientation of the transition conflict graph is valid for encoding the dynamic behavior of a system. © 2011 Springer-Verlag. Source

Cortez F.,National Polytechnic School of Ecuador
Mathematical Methods in the Applied Sciences | Year: 2016

In this paper, we consider the b-family of equations on the torus ut-utxx+(b + 1)uux=buxuxx+uuxxx, which for appropriate values of b reduces to well-known models, such as the Camassa-Holm equation or the Degasperis-Procesi equation. We establish a local-in-space blow-up criterion. © 2016 John Wiley & Sons, Ltd. Source

Torres L.M.,National Polytechnic School of Ecuador | Wagler A.K.,CNRS Laboratory of Informatics, Modeling and Optimization of Systems
RAIRO - Operations Research | Year: 2013

To model the dynamics of discrete deterministic systems, we extend the Petri nets framework by a priority relation between conflicting transitions, which is encoded by orienting the edges of a transition conflict graph. The aim of this paper is to gain some insight into the structure of this conflict graph and to characterize a class of suitable orientations by an analysis in the context of hypergraph theory. © EDP Sciences, ROADEF, SMAI 2013. Source

Lyons J.J.,National Polytechnic School of Ecuador | Waite G.P.,Michigan Technological University | Ichihara M.,University of Tokyo | Lees J.M.,University of North Carolina at Chapel Hill
Geophysical Research Letters | Year: 2012

Ground tilt is measured from broadband seismic records prior to frequent explosions at Fuego volcano, Guatemala. We are able to resolve tilt beginning 20-30 minutes prior to explosions, followed by a rapid reversal in deformation coincident with explosion onsets. The tilt amplitude and polarity recorded on the horizontal channels vary from station to station such that the steep and unusual topography of the upper cone of Fuego appears to affect the ultra-long-period signals. We account for the effect of topography and attempt to constrain the tilt source depth and geometry through finite-difference modeling. The results indicate a shallow spherical pressure source, and that topography must be considered when attempting to model tilt sources at volcanoes with steep topography. The tilt signals are interpreted as pressurization of the shallow conduit beneath a crystallized plug followed by elastic deflation concurrent with explosive pressure release. © 2012 by the American Geophysical Union. Source

Discover hidden collaborations