Shear wave velocity estimation in the metropolitan area of Málaga (S Spain)

We carry out a seismic noise study based on array measurements at three sites in the Málaga basin, South Spain, for the further estimation of shear wave velocity profiles. For this purpose, we use both the H/V method and the f–k technique in order to characterize the different materials present in the zone, i.e., Quaternary sediments and Pliocene sedimentary rocks above the bedrock. The H/V analysis shows frequency peaks going from 1 Hz, in areas close to the border of the basin, to 0.3 Hz in places located toward the center of the formation. The f–k analysis allows obtaining the dispersion curves associated with each site and subsequently, estimating the Vs profiles by inversion of the respective group velocities. In this way, the basin basement can be characterized by S-wave velocities greater than 2000 m/s. Regarding the basin fill, it is divided into three layers defined by different wave velocity intervals. The shallowest one is featured by velocities ranging from 150 to 400 m/s and comprises the Quaternary sediments, while velocities going from 550–700 to1200–1600 m/s characterize the two underlying layers composed by Pliocene sediments. Finally, the information provided by the three Vs profiles is integrated in a 2D cross-section of the basin to have a spatial view of its sedimentary structure. The results obtained here, in addition to providing useful information about the infill of the basin near the metropolitan area of Málaga, will be very helpful for future seismic zonation studies in the region.

Advanced interpretation of subsidence in Murcia (SE Spain) using A-DInSAR data – modelling and validation

Subsidence is a natural hazard that affects wide areas in the world causing important economic costs annually. This phenomenon has occurred in the metropolitan area of Murcia City (SE Spain) as a result of groundwater overexploitation. In this work aquifer system subsidence is investigated using an advanced differential SAR interferometry remote sensing technique (A-DInSAR) called Stable Point Network (SPN). The SPN derived displacement results, mainly the velocity displacement maps and the time series of the displacement, reveal that in the period 2004–2008 the rate of subsidence in Murcia metropolitan area doubled with respect to the previous period from 1995 to 2005. The acceleration of the deformation phenomenon is explained by the drought period started in 2006. The comparison of the temporal evolution of the displacements measured with the extensometers and the SPN technique shows an average absolute error of 3.9±3.8 mm. Finally, results from a finite element model developed to simulate the recorded time history subsidence from known water table height changes compares well with the SPN displacement time series estimations. This result demonstrates the potential of A-DInSAR techniques to validate subsidence prediction models as an alternative to using instrumental ground based techniques for validation.

Sistemas radar aplicados a la investigación de subsidencia y movimientos de ladera

En este trabajo se presentan los sistemas radar satélite y terrestres, así como los métodos de análisis de imágenes radar clásicos y avanzados para la investigación de los movimientos del terreno, haciendo énfasis en la subsidencia y los movimientos de ladera. Para ello en primer lugar se describen los distintos sensores radar disponibles así como las principales características de las imágenes radar generadas. A continuación se detallan los aspectos fundamentales de la interferometría diferencial, de los distintos métodos de interferometría diferencial avanzada y del radar terrestre. Finalmente se presentan los resultados obtenidos en distintas zonas de estudio: la subsidencia por explotación del acuífero en el área metropolitana de Murcia, la subsidencia minera y los movimientos de ladera de la Sierra de Cartagena, los movimientos de ladera de la cuenca del río Gállego y el deslizamiento del Portalet.

Computer Networks Virtualization with GNS3: Evaluating a solution to optimize resources and achieve a distance learning

Designing educational resources allow students to modify their learning process. In particular, on-line and downloadable educational resources have been successfully used in engineering education the last years [1]. Usually, these resources are free and accessible from web. In addition, they are designed and developed by lecturers and used by their students. But, they are rarely developed by students in order to be used by other students. In this work-in-progress, lecturers and students are working together to implement educational resources, which can be used by students to improve the learning process of computer networks subject in engineering studies. In particular, network topologies to model LAN (Local Area Network) and MAN (Metropolitan Area Network) are virtualized in order to simulate the behavior of the links and nodes when they are interconnected with different physical and logical design.

Cambios en la estructura metropolitana durante la última década. El caso del Área Metropolitana de Valencia

La realidad metropolitana de los países desarrollados está experimentando cambios importantes asociados a la creciente separación entre los espacios de residencia y trabajo. En las áreas metropolitanas se dan los procesos de este tipo más complejos cuyas consecuencias territoriales inmediatas son la potenciación de ciertas centralidades a la vez que crecen centros nuevos o tradicionales en sus áreas de influencia. La estructura territorial (la red urbana y de transportes, fundamentalmente) en el Área Metropolitana de Valencia (AMV) incide claramente en los problemas asociados a la equidad social y a la sostenibilidad ambiental. La comunicación que aquí se presenta se centra en el análisis de dichos cambios en la última década, a partir del comportamiento demográfico de los municipios, las pautas generales de movilidad y los cambios en la ocupación del suelo en el AMV.

Virtualización de Redes de Computadores con GNS3: Evaluación de soluciones para el aprendizaje a distancia

El diseño de los recursos educativos permite a los estudiantes modificar su proceso de aprendizaje. En particular, los recursos educativos on-line descargables han sido utilizados con éxito en la educación en ingeniería en los últimos años. Por lo general, estos recursos son gratuitos y accesibles desde la web. Además, son diseñados y desarrollados por profesores y usados por sus estudiantes. Pero, rara vez se desarrollan por los estudiantes con el fin de ser utilizados por otros estudiantes. En este artículo, profesores y estudiantes trabajan juntos para implementar recursos educativos de libre distribución, que puedan ser utilizados por los estudiantes para mejorar el proceso de aprendizaje de redes de computadores en los estudios de ingeniería. En particular, se virtualizan topologías de red para modelar redes LAN (Local Area Network) y MAN (Metropolitan Area Network) con el fin de simular el comportamiento de los enlaces y nodos cuando están interconectados con diferente diseño físico y lógico. Para ello, usando el software de libre distribución GNS3, y teniendo como base la configuración de la red del laboratorio L24 de la EPS, se construye un entorno virtual que simula las posibilidades reales de este laboratorio.

Evaluation of the potential of InSAR time series to study the spatio-temporal evolution of piezometric levels in the Madrid aquifer

The Tertiary detritic aquifer of Madrid (TDAM), with an average thickness of 1500 m and a heterogeneous, anisotropic structure, supplies water to Madrid, the most populated city of Spain (3.2 million inhabitants in the metropolitan area). Besides its complex structure, a previous work focused in the north-northwest of Madrid city showed that the aquifer behaves quasi elastically trough extraction/recovery cycles and ground uplifting during recovery periods compensates most of the ground subsidence measured during previous extraction periods (Ezquerro et al., 2014). Therefore, the relationship between ground deformation and groundwater level through time can be simulated using simple elastic models. In this work, we model the temporal evolution of the piezometric level in 19 wells of the TDAM in the period 1997–2010. Using InSAR and piezometric time series spanning the studied period, we first estimate the elastic storage coefficient (Ske) for every well. Both, the Ske of each well and the average Ske of all wells, are used to predict hydraulic heads at the different well locations during the study period and compared against the measured hydraulic heads, leading to very similar errors when using the Ske of each well and the average Ske of all wells: 14 and 16 % on average respectively. This result suggests that an average Ske can be used to estimate piezometric level variations in all the points where ground deformation has been measured by InSAR, thus allowing production of piezometric level maps for the different extraction/recovery cycles in the TDAM.