Análisis de la peligrosidad sísmica en la Península Ibérica con un método basado en estimadores de densidad Kernel

El presente trabajo estudia la peligrosidad sísmica en La Península Ibérica con un método basado en estimadores de densidad kernel. Se trata de una metodología no paramétrica en la que la tasa de actividad sísmica se deduce de la información contenida en el propio catálogo sísmico, tanto en lo que se refiere a su dependencia espacial (prescindiendo de hipótesis cuestionables sobre la uniformidad en zonas discretas) como en relación con la magnitud (obviando la ley de Gutenberg-Richter). El catálogo sísmico empleado es el del Instituto Geográfico Nacional (IGN) complementado con otros catálogos en las zonas periféricas en que pareció apropiado hacerlo. El catálogo se ha homogeneizado en lo que se refiere a la cuantificación de los terremotos, y se ha filtrado con objeto de eliminar eventos espacial o temporalmente interrelacionados ya que se asume el modelo temporal de Poisson. La tasa de actividad sísmica queda fijada por la forma de la función kernel, el ancho de banda y los períodos efectivos. Se especifican los valores considerados para cada uno de estos elementos. Asimismo, se presenta un análisis cualitativo y cuantitativo de la tasa de actividad sísmica obtenida, que permite establecer las similitudes y diferencias con respecto a la tasa de actividad que se obtendría con las estadísticas de Gutenberg-Richter y una metodología zonificada. La selección de leyes de atenuación ha sido especialmente cuidadosa, basada en el estado del conocimiento y haciendo un empleo riguroso de los modelos seleccionados en lo referente a su campo de aplicación o a la definición de las variables de las que depende o que proporciona. Se han empleado tres leyes de atenuación: una para terremotos profundos y las otras dos para terremotos superficiales, en función de que su magnitud fuera superior o inferior a 5, para ceñir el uso de las leyes a su rango de soporte. Los resultados se obtienen en términos de aceleración y se presentan en tres formatos: mapas de peligrosidad sísmica, curvas de peligrosidad y espectros de peligrosidad uniforme. Abstract The seismic hazard of The Iberian Peninsula has been analysed in the present work using a non-parametric methodology based on kernel density estimators. The activity rate was derived from the information provided in the seismic catalogue, both in respect of its dependence on spatial location (disregarding questionable hypothesis of uniformity over discrete zones) and in relation with the event magnitude (obviating the use of the Gutenberg- Richter law). The seismic catalogue employed was that by Instituto Geográfico Nacional (IGN), supplemented for peripherial regions with other catalogues as appropriate. The quantification of events was homogenised throughout the catalogue and spatially or temporally related events were condensed for consistency with the assumed Poisson process. The seismic activity rate is given by the shape of the kernel function, the bandwidth and the effective periods; the values used for those parameters have all been specified. Also, qualitative and quantitative analyses of the seismic activity rate have been provided, thus allowing comparisons with the results produced using Gutenberg-Richter statistics and a zoned approach. Special care was taken in the selection of attenuation laws, taking into account the state of the art and ensuring that each law is only used within its range of applicability and that the definitions of the variables involved in the model are properly taken into account. Three attenuation laws were employed: one for deep sources and the other two for shallower events, depending on whether their magnitude was above or below 5, restricting the use of each model to its support range. The results were obtained in terms of acceleration and presented in three different formats: seismic hazard maps, hazard curves and uniform hazard spectra

Incorporación de actividad sísmica no reflejada en el catálogo en métodos no zonificados

Las evaluaciones de la peligrosidad sísmica suelen apoyarse en la información del catálogo. El período de retorno de los cálculos probabilistas debe ser consistente con las tasas de ocurrencia representadas en la caracterización de la actividad. En la metodología de Gutenberg-Richter (GR) se fija una magnitud máxima de integración que acota la validez de la ley de GR, siendo frecuente que el rango cubierto por la ley de GR exceda al cubierto por el catálogo que la soporta. En un método no zonificado la tasa de actividad se construye a partir de los eventos del catálogo y es sólo representativa de dichos eventos, aunque la incorporación de incertidumbres y el adecuado manejo de los períodos efectivos pueden incrementar los períodos de retorno respecto al rango cubierto por el catálogo. Se expone aquí una estrategia para incorporar información paleosísmica en una metodología basada en estimadores de densidad kernel

Seismic Activity Rates in the Iberian Peninsula

Evaluating the seismic hazard requires establishing a distribution of the seismic activity rate, irrespective of the methodology used in the evaluation. In practice, how that activity rate is established tends to be the main difference between the various evaluation methods. The traditional procedure relies on a seismogenic zonation and the Gutenberg-Richter (GR) hypothesis. Competing zonations are often compared looking only at the geometry of the zones, but the resulting activity rate is affected by both geometry and the values assigned to the GR parameters. Contour plots can be used for conducting more meaningful comparisons, providing the GR parameters are suitably normalised. More recent approaches for establishing the seismic activity rate forego the use of zones and GR statistics and special attention is paid here to such procedures. The paper presents comparisons between the local activity rates that result for the complete Iberian Peninsula using kernel estimators as well as two seismogenic zonations. It is concluded that the smooth variation of the seismic activity rate produced by zoneless methods is more realistic than the stepwise changes associated with zoned approaches; moreover, the choice of zonation often has a stronger influence on the results than its fairly subjective origin would warrant. It is also observed that the activity rate derived from the kernel approach, related with the GR parameter “a”, is qualitatively consistent with the epicentres in the catalogue. Finally, when comparing alternative zonations it is not just their geometry but the distribution of activity rate that should be compared

Seismic Isolation of Liquefied Natural Gas Tanks: a Compartive Assessment

In severe seismic environments, tanks for storage of liquefied natural gas may benefit from seismic isolation. As the design accelerations increase, the inner tank undergoes progressively greater demands and may suffer from corner uplift, elephant’s foot buckling, gross sliding, shell thickness requirements beyond what can be reliably welded and, eventually, global uplift. Some of these problems cause extra costs while others make the construction impossible. The seismic environments at which the previous problems arise are quantified for modern 160,000 m3 tanks, whether supported on shallow or pile foundations, for both a conventional design and one employing seismic isolation. Additionally, by introducing some cost assumptions, comparisons can be made as to the cost of dealing with the seismic threat for each seismic environment and tank design option. It then becomes possible to establish the seismic environments that require seismic isolation, as well as to offer guidance for decisions in intermediate cases

Seismic hazards of the Iberian Peninsula - evaluation with Kernel functions

The seismic hazard of the Iberian Peninsula is analysed using a nonparametric methodology based on statistical kernel functions; the activity rate is derived from the catalogue data, both its spatial dependence (without a seismogenetic zonation) and its magnitude dependence (without using Gutenberg–Richter's law). The catalogue is that of the Instituto Geográfico Nacional, supplemented with other catalogues around the periphery; the quantification of events has been homogenised and spatially or temporally interrelated events have been suppressed to assume a Poisson process. The activity rate is determined by the kernel function, the bandwidth and the effective periods. The resulting rate is compared with that produced using Gutenberg–Richter statistics and a zoned approach. Three attenuation laws have been employed, one for deep sources and two for shallower events, depending on whether their magnitude was above or below 5. The results are presented as seismic hazard maps for different spectral frequencies and for return periods of 475 and 2475 yr, which allows constructing uniform hazard spectra

Peligrosidad sísmica en la península ibérica

Se estudia la peligrosidad sísmica en la Península Ibérica con una metodología no paramétrica basada en estimadores de densidad kernel; la tasa de actividad se deduce del catálogo, tanto en cuanto a su dependencia espacial (prescindiendo de zonificación) como en relación con la magnitud (obviando la ley de Gutenberg-Richter). El catálogo es el del Instituto Geográfico Nacional, complementado con otros en zonas periféricas, homogeneizado en su cuantificación de los terremotos y eliminando eventos espacial o temporalmente interrelacionados para mantener un modelo temporal de Poisson. La tasa de actividad sísmica viene determinada por la función kernel, el ancho de banda y los períodos efectivos. La tasa resultante se compara con la obtenida usando estadísticas de Gutenberg-Richter y una metodología zonificada. Se han empleado tres leyes de atenuación: una para terremotos profundos y dos para terremotos superficiales, dependiendo de que su magnitud fuera superior o inferior a 5. Los resultados se presentan en forma de mapas de peligrosidad para diversas frecuencias espectrales y períodos de retorno de 475 y 2475 años, lo que permite construir espectros de peligrosidad uniforme

Percepção dos estudantes sobre comportamento no ensino do professor e satisfação com a Educação Física: uma questão de gênero?

Este estudio analiza la satisfacción con la Educación Física (EF) y la percepción del comportamiento instructivo del profesor (CIP). Participaron 2.536 estudiantes (edad 13,7 ± 2,0). Se aplicaron dos escalas: a) escala de satisfacción con la EF; y b) escala de comportamientos instructivos del profesorado. Los resultados muestran una elevada satisfacción con la EF y la percepción de una buena frecuencia del CIP. Existen algunas diferencias significativas en función del género de los alumnos y profesores. No se produce empatía de género descrita en otros estudios: chicos y chicas perciben mayor frecuencia de comportamientos instructivos deseables cuando el profesor es mujer.Este trabalho analisa a satisfação com a educação física (EF) e a percepção do comportamento no ensino do professor. Participaram 2.536 estudantes (idade 13,77 ± 2,0). Foram aplicadas duas escalas: a) escala de satisfação com a educação física; y b) escala de comportamento no ensino dos professores. Os resultados demonstram uma alta satisfação com a EF, bem como a percepção de uma boa freqüência do comportamento no ensino do professor. Existem algumas diferenças significativas em função do gênero dos alunos e professores. Não há relação direta de simpatia de gênero encontrada em outros estudos: meninos e meninas percebem com mais frequência um comportamento no ensino do professor de maneira desejável, quando ele é uma mulher.The purposes of this study were to analyze the satisfaction with PE and the perception of the students about of the Teacher´ Instructional Behaviours. Participants were 2,536 students (13.7 ± 2.0 years old). Two scales were applied: a) the satisfaction with PE scale; and b) the scale of perception of the Teacher´ Instructional Behaviours. The results illustrate a high level of satisfaction with PE. Students perceive instructional desirable behaviours of their teachers occur frequently. The findings show some significant differences in gender. There is not empathy of gender: both boys and girls perceive more f requent instructional desirable behaviour when the teacher is female.Estudio financiado por el Ministerio Español de Ciencia y Tecnología (Proyecto código SEJ2007-67267/EDU

Fluid-Structure Interaction in Civil Engineering Structures

The problems being addressed involve the dynamic interaction of solids (structure and foundation) with a liquid (water). Various numerical procedures are reviewed and employed to solve the problem of establishing the expected response of a structure subjected to seismic excitations while duly accounting for those interactions. The methodology is applied to the analysis of dams, lock gates, and large storage tanks, incorporating in some cases a comparison with the results produced by means of simplified analytical procedures

Towards a new seismic hazard assessment in Spain

Seismic hazard is an evolving science that is fed by geological and seismological studies. As new data and models arise, the revision of hazard maps is compelling. Additionally, understanding the nature and the sources of the uncertainties involved in seismic hazard analyses is essential in order to reduce them. In this context, Spain is not an exception and a move towards a reassessment of the national hazard maps is pertinent. Several hazard-controlling factors needing to be updated and eventually revaluated are identified in this work in progress. The first one concerns the seismic catalogue. It must be homogenised, incorporating data from neighbouring countries and correlating magnitude scales for different regions and recording periods. A second factor refers to seismicity characterization by zoning and zoneless models: Neotectonic, seismological and other geological data that justify the development of a new zoning model for Spain and adjacent areas are disclosed. Revaluation of seismic areas that are traditionally considered as stable but show evidence of seismic activity at present and during Quaternary times needs to be considered. The interest of developing a neotectonic characterization of active faults is advanced. For zoneless models, the different elements that define the continuous spatial variation of the activity rate density have to be examined. For a zoneless model based on kernel functions, these elements would be the specific type of kernel function, the bandwidth and the reference years. A third factor requiring a modern analysis refers to the implementation of different strong motion prediction models. These include models based on local data and developed with data from other regions. Special attention is paid to the application of the next generation attenuation models originally developed for western North America to Spain. Criteria for selecting different models must be clearly and thoughtfully enumerated. The final goal of this work is to assess the variability of seismic hazard results to the new data and models that are becoming available. Such information will be of indubitable interest for forthcoming versions of the seismic code, national annexes of Eurocode 8 and research projects fomented by the Spanish Nuclear Security Counci

A Sparse-Bayesian Approach for the Design of Robust Digital Predistorters Under Power-Varying Operation

"Early access"In this article, a sparse-Bayesian treatment is proposed to solve the crucial questions posed by power amplifier (PA) and digital predistorter (DPD) modeling. To learn a model, the advanced Bayesian framework includes a group of specific processes that maximize the likelihood of the measured data: regressor pursuit and identification, coefficient estimation, stopping criterion, and regressor deselection. The relevance vector machine (RVM) method is reformulated theoretically to be implemented in complex-valued linear regression. In essence, given an initial set of candidate regressors, the result of this sparse-Bayesian learning approach is the most likely model. Experimental results are provided for the linearization of class AB and class J PAs driven by a 30-MHz fifth-generation new radio signal for a fixed average power, where the evolution of the figures of merit versus the number of active coefficients is examined for the proposed sparse-Bayesian pursuit (SBP) algorithm in comparison to other greedy algorithms. The SBP presents a good performance in terms of linearization capabilities and computational cost. Furthermore, the proposed Bayesian framework enabled the design of a DPD model structure, deselect regressors, and readjust coefficients in a direct learning architecture, demonstrating the robustness to changes in the power level over a 10-dB range.Ministerio de Ciencia e Innovación 10.13039/501100011033Junta de Andalucía - Fondos FEDER US-126499