GIES - Geofísica i Enginyeria Sísmica
http://hdl.handle.net/2117/477
Sun, 29 May 2016 11:36:15 GMT2016-05-29T11:36:15ZDetección de galerías de agua en Barcelona
http://hdl.handle.net/2117/87398
Detección de galerías de agua en Barcelona
Caselles Magallón, Josep Oriol; Clapes Boixader, Jaime; Osorio Gómez, Raúl; Pujades Beneit, Lluís; Canas Torres, José Antonio; Pérez Gracia, María de la Vega
Several zones of the northern part of Barcelona City have old water mining galleries located in the upper part of the granite formation. These galleries are now out of use and their localization are unkown. This fact involves some problemes when foundations are built near or over them. Usually geothecnical or geophysical prospecting are only carried out to detect these underground galleries when foundation has been already built and, therefore, geophysical prospecting is more difficult and hard to carry out. The presence of parts of the totally of the building foundation makes very difficult to apply some of the geophysical prospecting techniques like some electromagnetic ones. GPR prospecting surveys are one of the few techniques that are little influenced by near undergound objects, only being affected by down metallic objects or water cables. In this work we present an example of a georradar survey made in Barcelona when building foundation was already made.
Thu, 26 May 2016 16:32:06 GMThttp://hdl.handle.net/2117/873982016-05-26T16:32:06ZCaselles Magallón, Josep OriolClapes Boixader, JaimeOsorio Gómez, RaúlPujades Beneit, LluísCanas Torres, José AntonioPérez Gracia, María de la VegaSeveral zones of the northern part of Barcelona City have old water mining galleries located in the upper part of the granite formation. These galleries are now out of use and their localization are unkown. This fact involves some problemes when foundations are built near or over them. Usually geothecnical or geophysical prospecting are only carried out to detect these underground galleries when foundation has been already built and, therefore, geophysical prospecting is more difficult and hard to carry out. The presence of parts of the totally of the building foundation makes very difficult to apply some of the geophysical prospecting techniques like some electromagnetic ones. GPR prospecting surveys are one of the few techniques that are little influenced by near undergound objects, only being affected by down metallic objects or water cables. In this work we present an example of a georradar survey made in Barcelona when building foundation was already made.Short period Rayleigh-wave dispersion applied to the determination of shallow structure.
http://hdl.handle.net/2117/87395
Short period Rayleigh-wave dispersion applied to the determination of shallow structure.
Navarro, M; Corchete Fernández, Víctor; Badal, J; Vidal, F; Canas Torres, José Antonio; Pujades Beneit, Lluís; Caselles Magallón, Josep Oriol
Very short-period surface waves are useful to obtai.n the models of
shear velocity structure at shallow crustal depths. In this study, we have investigated the shear velocity shallow crustal structure of the Andarax basin (Almeria province) and Granada basin (Granada province) located in southern Spain, from inversion of fundamental mode Rayleigh wave group velocity curves generated by blasts. The analysis and inversion of Rayleigh waveforms is performed using digital filtering techniques and a generalized inversion approach. A timevariable filter has reduced the influence of noise and removed higher mode interference and multiple filtering is then used to compute group velocities from 1.13 to 1.50 km s-1 for a period range between 0.6 and 2.0 sin Andarax basin. We have obtained group velocities values between 0.83 and 1.22 km s-1 for a period range from 1.4 to 3.4 s in Granada basin. We have performed inversion for velocity
structure by stochastic inversion of the dispersion data, so that we have obtained shear wave velocity model down to 2 km depth for Andarax basin which shows velocities between 1.26 and 2.58 km s-1 with a standard desviation band of 0.03-0.08 km s-1 and down to 5 km for Granada basin which shows velocities from 1.01 to 3.14 km s-1 with a standard desviation band of 0.05-0.26 km s-1. The shear velocity model for Andarax basin exhibits a low-velocity channel at depths between 200 and 500 m whereas in Granada basin the shear velocity values increases with depth. In order to guarantee the reliability of our results, we have proceeded to compute the resolution kemels at various reference depths for and observed a good coincidence between the absolute maximun of any kernels and the respective referece depth, which implies a good agreement between the calculated solution and the true solution at these depths.
Thu, 26 May 2016 15:24:47 GMThttp://hdl.handle.net/2117/873952016-05-26T15:24:47ZNavarro, MCorchete Fernández, VíctorBadal, JVidal, FCanas Torres, José AntonioPujades Beneit, LluísCaselles Magallón, Josep OriolVery short-period surface waves are useful to obtai.n the models of
shear velocity structure at shallow crustal depths. In this study, we have investigated the shear velocity shallow crustal structure of the Andarax basin (Almeria province) and Granada basin (Granada province) located in southern Spain, from inversion of fundamental mode Rayleigh wave group velocity curves generated by blasts. The analysis and inversion of Rayleigh waveforms is performed using digital filtering techniques and a generalized inversion approach. A timevariable filter has reduced the influence of noise and removed higher mode interference and multiple filtering is then used to compute group velocities from 1.13 to 1.50 km s-1 for a period range between 0.6 and 2.0 sin Andarax basin. We have obtained group velocities values between 0.83 and 1.22 km s-1 for a period range from 1.4 to 3.4 s in Granada basin. We have performed inversion for velocity
structure by stochastic inversion of the dispersion data, so that we have obtained shear wave velocity model down to 2 km depth for Andarax basin which shows velocities between 1.26 and 2.58 km s-1 with a standard desviation band of 0.03-0.08 km s-1 and down to 5 km for Granada basin which shows velocities from 1.01 to 3.14 km s-1 with a standard desviation band of 0.05-0.26 km s-1. The shear velocity model for Andarax basin exhibits a low-velocity channel at depths between 200 and 500 m whereas in Granada basin the shear velocity values increases with depth. In order to guarantee the reliability of our results, we have proceeded to compute the resolution kemels at various reference depths for and observed a good coincidence between the absolute maximun of any kernels and the respective referece depth, which implies a good agreement between the calculated solution and the true solution at these depths.Variación del periodo propio de un edificio durante su construcción
http://hdl.handle.net/2117/87394
Variación del periodo propio de un edificio durante su construcción
Espinoza Barreras, Fortunato; Caselles Magallón, Josep Oriol; Mena Hernandez, Ulises; Cruz, De La S T; Pujades Beneit, Lluís; Canas Torres, José Antonio; Clapes Boixader, Jaime
El ruido cultural o vibración ambiental se genera por el hombre debido a la maquinaria industrial, por el tráfico de vehículos, por el viento, por cambios en presión atmosférica, por actividad volcánica interna, etcétera, y se utiliza para determinar características dinámicas de suelos y estructuras entre otras aplicaciones. Las pruebas de víbración ambiental tienen la ventaja de ser eficientes, rápidas y de bajo coste. La información lograda permite mejorar el proceso de construcción de modelos matemáticos de sistemas dinámicos realizando un ajuste de sus parámetros de tal manera que se establezca la mejor correlación posible entre las respuestas predichas por el modelo y las obtenidas experimentalmente. La frecuencia natural o su inverso, el periodo propio, es de entre las características dinámicas, el parámetro más importante para la estimación de las condiciones físicas de las
estructuras. En la ciudad de Barcelona se está realizando un estudio para determinar los periodos propios de los edificios utilizando vibración ambiental como fuente de excitación.
En este trabajo se presentan los resultados obtenidos al realizar mediciones durante tres etapas de la construcción de un edificio mixto, de hormigón armado y acero, de ocho niveles. Se busca determinar la influencia de los elementos no estructurales analizando el comportamiento del periodo propio. Los resultados preliminares muestran que el periodo disminuye a medida que se incorporan elementos no estructurales al edificio, indicando un aumento de su rigidez.
Thu, 26 May 2016 15:20:39 GMThttp://hdl.handle.net/2117/873942016-05-26T15:20:39ZEspinoza Barreras, FortunatoCaselles Magallón, Josep OriolMena Hernandez, UlisesCruz, De La S TPujades Beneit, LluísCanas Torres, José AntonioClapes Boixader, JaimeEl ruido cultural o vibración ambiental se genera por el hombre debido a la maquinaria industrial, por el tráfico de vehículos, por el viento, por cambios en presión atmosférica, por actividad volcánica interna, etcétera, y se utiliza para determinar características dinámicas de suelos y estructuras entre otras aplicaciones. Las pruebas de víbración ambiental tienen la ventaja de ser eficientes, rápidas y de bajo coste. La información lograda permite mejorar el proceso de construcción de modelos matemáticos de sistemas dinámicos realizando un ajuste de sus parámetros de tal manera que se establezca la mejor correlación posible entre las respuestas predichas por el modelo y las obtenidas experimentalmente. La frecuencia natural o su inverso, el periodo propio, es de entre las características dinámicas, el parámetro más importante para la estimación de las condiciones físicas de las
estructuras. En la ciudad de Barcelona se está realizando un estudio para determinar los periodos propios de los edificios utilizando vibración ambiental como fuente de excitación.
En este trabajo se presentan los resultados obtenidos al realizar mediciones durante tres etapas de la construcción de un edificio mixto, de hormigón armado y acero, de ocho niveles. Se busca determinar la influencia de los elementos no estructurales analizando el comportamiento del periodo propio. Los resultados preliminares muestran que el periodo disminuye a medida que se incorporan elementos no estructurales al edificio, indicando un aumento de su rigidez.Spectral analysis of the Beznar dam accelerogram. Comparison with results in the northeastern of Spain
http://hdl.handle.net/2117/87083
Spectral analysis of the Beznar dam accelerogram. Comparison with results in the northeastern of Spain
Canas Torres, José Antonio; Barbat Barbat, Horia Alejandro; Pujades Beneit, Lluís; Egozcue Rubí, Juan José; Sarrate Ramos, Josep
Numerical analysis applied to the Beznar dam accelerograms (longitudinal and transversal components) shows that the Fourier amplitude spectrum is a good approximation to the pseudo-velocity spectra. Thís fact makes possible to use displacement ar velocíty seismograrns to generate acceleration of the ground in places
where acceleration data are not available.
Maximae accelerations determined near and at the Beznar dam are compared wíth the predicted acceleration values far the regían compressed by the Pyrenees Mountains, the lberic System and the Catalonia Coastal Mountains usíng a established theoretical formula
far this region. Theoretical and observad values are consistent among them.
Tue, 17 May 2016 07:55:41 GMThttp://hdl.handle.net/2117/870832016-05-17T07:55:41ZCanas Torres, José AntonioBarbat Barbat, Horia AlejandroPujades Beneit, LluísEgozcue Rubí, Juan JoséSarrate Ramos, JosepNumerical analysis applied to the Beznar dam accelerograms (longitudinal and transversal components) shows that the Fourier amplitude spectrum is a good approximation to the pseudo-velocity spectra. Thís fact makes possible to use displacement ar velocíty seismograrns to generate acceleration of the ground in places
where acceleration data are not available.
Maximae accelerations determined near and at the Beznar dam are compared wíth the predicted acceleration values far the regían compressed by the Pyrenees Mountains, the lberic System and the Catalonia Coastal Mountains usíng a established theoretical formula
far this region. Theoretical and observad values are consistent among them.Prioritizing interventions to reduce seismic vulnerability in school facilities in Colombia
http://hdl.handle.net/2117/86746
Prioritizing interventions to reduce seismic vulnerability in school facilities in Colombia
Mora, Miguel G.; Valcarcel Torres, Jairo Andrés; Cardona, Omar D.; Pujades Beneit, Lluís; Barbat Barbat, Horia Alejandro; Bernal Granados, Gabriel Andres
Colombian seismic code NSR-98 establishes the requirement for t he seismic vulnerability analysis and, if necessary, the strengthening of public facilities (schools). Due to the investments required by risk reduction pr ograms, it is necessary to establish criteria for assigning priorities for th e interventions. This article proposes a methodology for obtaining a Benefit-Cost Rat io (BCR) at the subnational level, by assessing the expected annual average los s of the built area of public schools and the retrofitting cost. The BCR is estimat ed as the difference between the estimates of the net present value for status quo a nd retrofitted states, these two divided by the retrofitting costs. According to the B CR, 47.3% of the total school built area of Colombia should be retrofitted where the retrofitting costs correspond to 25% of the total investment. Proposed BCR i s useful for prioritizing regions in functi on of the feasibility of reducing the seismic vulnerability of the schools.
Mon, 09 May 2016 08:35:22 GMThttp://hdl.handle.net/2117/867462016-05-09T08:35:22ZMora, Miguel G.Valcarcel Torres, Jairo AndrésCardona, Omar D.Pujades Beneit, LluísBarbat Barbat, Horia AlejandroBernal Granados, Gabriel AndresColombian seismic code NSR-98 establishes the requirement for t he seismic vulnerability analysis and, if necessary, the strengthening of public facilities (schools). Due to the investments required by risk reduction pr ograms, it is necessary to establish criteria for assigning priorities for th e interventions. This article proposes a methodology for obtaining a Benefit-Cost Rat io (BCR) at the subnational level, by assessing the expected annual average los s of the built area of public schools and the retrofitting cost. The BCR is estimat ed as the difference between the estimates of the net present value for status quo a nd retrofitted states, these two divided by the retrofitting costs. According to the B CR, 47.3% of the total school built area of Colombia should be retrofitted where the retrofitting costs correspond to 25% of the total investment. Proposed BCR i s useful for prioritizing regions in functi on of the feasibility of reducing the seismic vulnerability of the schools.Partial duration series distributions of the European dry spell lengths for the second half of the twentieth century
http://hdl.handle.net/2117/85539
Partial duration series distributions of the European dry spell lengths for the second half of the twentieth century
Serra de Larrocha, Carina; Lana Pons, Francisco Javier; Burgueño Rivero, August; Martínez Santafé, Maria Dolors
A spatial analysis of partial duration series, PDS, of the dry spell lengths, DSL, is applied to 267 European stations during years 1951–2000. A DSL is defined as the number of consecutive days with precipitation below 0.1 mm/day. For every station, PDS are made of DSL longer than those corresponding to 95th empirical percentile. The L-skewness and L-kurtosis diagram of the PDS distributions shows that most of the stations fit well a generalised Pareto, GP, model. Only four rain gauge records at the southeast Mediterranean coast notably depart from this model. In addition, DSL maps for return periods of 2, 5, 10, 25 and 50 years are introduced by taking into account GP parameters, which are estimated by fitting the GP distribution to empirical PDS distributions of DSL. A comparative study with those obtained in a previous paper, for the whole DSL series and the corresponding best distribution model (Pearson type III), shows that the differences of DSL for the different return periods keep within ±10 % in most of rain gauges. Moreover, a principal component analysis, PCA, is applied to the four first L-moments of the 267 rain gauges. Then, a regionalization in 11 groups is obtained after the clustering process. Finally, a regional frequency analysis is attempted, being possible to assign a GP parent distribution with different parameters to 7 out of the 11 groups.
Tue, 12 Apr 2016 09:57:25 GMThttp://hdl.handle.net/2117/855392016-04-12T09:57:25ZSerra de Larrocha, CarinaLana Pons, Francisco JavierBurgueño Rivero, AugustMartínez Santafé, Maria DolorsA spatial analysis of partial duration series, PDS, of the dry spell lengths, DSL, is applied to 267 European stations during years 1951–2000. A DSL is defined as the number of consecutive days with precipitation below 0.1 mm/day. For every station, PDS are made of DSL longer than those corresponding to 95th empirical percentile. The L-skewness and L-kurtosis diagram of the PDS distributions shows that most of the stations fit well a generalised Pareto, GP, model. Only four rain gauge records at the southeast Mediterranean coast notably depart from this model. In addition, DSL maps for return periods of 2, 5, 10, 25 and 50 years are introduced by taking into account GP parameters, which are estimated by fitting the GP distribution to empirical PDS distributions of DSL. A comparative study with those obtained in a previous paper, for the whole DSL series and the corresponding best distribution model (Pearson type III), shows that the differences of DSL for the different return periods keep within ±10 % in most of rain gauges. Moreover, a principal component analysis, PCA, is applied to the four first L-moments of the 267 rain gauges. Then, a regionalization in 11 groups is obtained after the clustering process. Finally, a regional frequency analysis is attempted, being possible to assign a GP parent distribution with different parameters to 7 out of the 11 groups.Seismic coda attenuation after the Mw=6.2 Armenia (Colombia) earthquake of 25 January 25, 1999
http://hdl.handle.net/2117/83596
Seismic coda attenuation after the Mw=6.2 Armenia (Colombia) earthquake of 25 January 25, 1999
Ugalde, Arantza; Vargas, C A; Pujades Beneit, Lluís; Canas Torres, José Antonio
Seismic wave attenuation in the central region of the Colombian Andes is studied using coda waves. Most of the events used occurred in the region on the occasion of the Armenia 25 January 1999 earthquake. The estimation of the decay rate of coda amplitudes (called coda Q-1 or Qc-1) is performed by means of the single isotropic scattering method of Sato [1977]. The attenuation parameters Qi-1 (intrinsic absorption), Qs-1 (scattering loss), and Qt-1 (total attenuation) are also estimated using the multiple lapse time window method of Hoshiba et al. [1991]. The frequencies of interest lie between 1 and 15 Hz. Results show that scattering attenuation is predominant for the frequency bands 1.5 ± 0.5 and 13.5 ± 1.5 Hz, whereas the intrinsic absorption and scattering contribute in equal shares to total attenuation for the 3 ± 1, 5 ± 1, 7.5 ± 1.5, and 10.5 ± 1.5 Hz frequencies. A comparison among the estimated attenuation parameters indicates that Qc-1 is close to total attenuation for all the studied frequency bands. On the other hand, no evidence in support of temporal changes of Qc-1 before and after the main shock has been found. Finally, the regionalization of Qc-1 values seems to correlate well with the geotectonic characteristics of the region.
Tue, 01 Mar 2016 11:34:12 GMThttp://hdl.handle.net/2117/835962016-03-01T11:34:12ZUgalde, ArantzaVargas, C APujades Beneit, LluísCanas Torres, José AntonioSeismic wave attenuation in the central region of the Colombian Andes is studied using coda waves. Most of the events used occurred in the region on the occasion of the Armenia 25 January 1999 earthquake. The estimation of the decay rate of coda amplitudes (called coda Q-1 or Qc-1) is performed by means of the single isotropic scattering method of Sato [1977]. The attenuation parameters Qi-1 (intrinsic absorption), Qs-1 (scattering loss), and Qt-1 (total attenuation) are also estimated using the multiple lapse time window method of Hoshiba et al. [1991]. The frequencies of interest lie between 1 and 15 Hz. Results show that scattering attenuation is predominant for the frequency bands 1.5 ± 0.5 and 13.5 ± 1.5 Hz, whereas the intrinsic absorption and scattering contribute in equal shares to total attenuation for the 3 ± 1, 5 ± 1, 7.5 ± 1.5, and 10.5 ± 1.5 Hz frequencies. A comparison among the estimated attenuation parameters indicates that Qc-1 is close to total attenuation for all the studied frequency bands. On the other hand, no evidence in support of temporal changes of Qc-1 before and after the main shock has been found. Finally, the regionalization of Qc-1 values seems to correlate well with the geotectonic characteristics of the region.Preliminary objective regionalization of the Mediterranean basin derived from surface-wave tomography
http://hdl.handle.net/2117/83388
Preliminary objective regionalization of the Mediterranean basin derived from surface-wave tomography
Martínez Santafé, Maria Dolors; Lana Pons, Francisco Javier; Badal, Jose; Canas Torres, José Antonio; Pujades Beneit, Lluís
An objective regionalization of the Mediterranean basin is derived from a tomographic study based on the fundamental mode of Rayleigh waves. The database is formed by seismic wavetrains recorded at very-broadband stations belonging to MedNet and other cooperative stations, located in the Mediterranean area. The data treatment consists of application of spectral filtering techniques aimed to determine path-averaged group velocities, computation of local group velocity maps for some periods and classification of the studied area in several homogeneous regions according to Principal Component Analysis (PCA) and Average Linkage (AL) algorithms. Finally, the group velocity dispersion curves representing each homogeneous region are compared and possible correlation between these regions and seismotectonic and structural characteristics are discussed.
Wed, 24 Feb 2016 13:30:04 GMThttp://hdl.handle.net/2117/833882016-02-24T13:30:04ZMartínez Santafé, Maria DolorsLana Pons, Francisco JavierBadal, JoseCanas Torres, José AntonioPujades Beneit, LluísAn objective regionalization of the Mediterranean basin is derived from a tomographic study based on the fundamental mode of Rayleigh waves. The database is formed by seismic wavetrains recorded at very-broadband stations belonging to MedNet and other cooperative stations, located in the Mediterranean area. The data treatment consists of application of spectral filtering techniques aimed to determine path-averaged group velocities, computation of local group velocity maps for some periods and classification of the studied area in several homogeneous regions according to Principal Component Analysis (PCA) and Average Linkage (AL) algorithms. Finally, the group velocity dispersion curves representing each homogeneous region are compared and possible correlation between these regions and seismotectonic and structural characteristics are discussed.Statistical distribution of elapsed times and distances of seismic events: the case of the Southern Spain seismic catalogue
http://hdl.handle.net/2117/83233
Statistical distribution of elapsed times and distances of seismic events: the case of the Southern Spain seismic catalogue
Martínez Santafé, Maria Dolors; Lana Pons, Francisco Javier; Posadas, A M; Pujades Beneit, Lluís
Several empiric cumulative distributions of elapsed times and distances between seismic events occurred in the Southern Iberian Peninsula from 1985 to 2000 (data extracted from the seismic catalogue of the Andalusian Institute of Geophysics) are investigated. Elapsed times and distances between consecutive seismic events of the whole
catalogue, taking into account threshold magnitudes of 2.5, 3.0, 3.5 and 4.0, and of five seismic crises, without distinguishing magnitudes, are investigated. Additionally, the series of distances and elapsed times from the main event to every aftershock are also analysed for the five seismic crises. Even though a power law is sometimes a satisfactory model for the cumulative distribution of elapsed times and distances between seismic events, in some cases a fit with a Weibull distribution for elapsed times performs better. It is worth of mention that, in the case of the seismic crises, the fit achieved by the power law is sometimes improved when it is combined with a logarithmic law. The results derived might be a contribution to a better representation of the seismic activity by means of models that could be based on random-walk processes.
Mon, 22 Feb 2016 11:49:01 GMThttp://hdl.handle.net/2117/832332016-02-22T11:49:01ZMartínez Santafé, Maria DolorsLana Pons, Francisco JavierPosadas, A MPujades Beneit, LluísSeveral empiric cumulative distributions of elapsed times and distances between seismic events occurred in the Southern Iberian Peninsula from 1985 to 2000 (data extracted from the seismic catalogue of the Andalusian Institute of Geophysics) are investigated. Elapsed times and distances between consecutive seismic events of the whole
catalogue, taking into account threshold magnitudes of 2.5, 3.0, 3.5 and 4.0, and of five seismic crises, without distinguishing magnitudes, are investigated. Additionally, the series of distances and elapsed times from the main event to every aftershock are also analysed for the five seismic crises. Even though a power law is sometimes a satisfactory model for the cumulative distribution of elapsed times and distances between seismic events, in some cases a fit with a Weibull distribution for elapsed times performs better. It is worth of mention that, in the case of the seismic crises, the fit achieved by the power law is sometimes improved when it is combined with a logarithmic law. The results derived might be a contribution to a better representation of the seismic activity by means of models that could be based on random-walk processes.Multifractality and autoregressive processes of dry spell lengths in Europe: an approach to their complexity and predictability
http://hdl.handle.net/2117/82075
Multifractality and autoregressive processes of dry spell lengths in Europe: an approach to their complexity and predictability
Martínez Santafé, Maria Dolors; Lana Pons, Francisco Javier; Burgueño Rivero, August; Serra de Larrocha, Carina
Tue, 26 Jan 2016 17:42:02 GMThttp://hdl.handle.net/2117/820752016-01-26T17:42:02ZMartínez Santafé, Maria DolorsLana Pons, Francisco JavierBurgueño Rivero, AugustSerra de Larrocha, Carina