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- Validation of the Lower Tagus Valley velocity and structural model using ambient noise broadband measurementsPublication . Torres, Ricardo Jorge Gomes; Furtado, José Augusto; Silva, H. G.; Borges, José Fernando; Caldeira, Bento; Bezzeghoud, Mourad; Pinto, Carlos C.; Carvalho, João
- New seismic source zone model for Portugal and Azores for use in SHARE: methodology and preliminar resultsPublication . Vilanova, Susana; Oliveira, Carlos Sousa; Silveira, A. Brum da; Madeira, J.; Nemser, Eliza; Fonseca, J. F. B. D.; Arvidsson, R.; Besana-Ostman, G. M.; Bezzeghoud, Mourad; Borges, José Fernando; Cabral, João; Carvalho, João P. F.; Cunha, Pedro Proença e; Dias, Ruben Pereira; Lopes, Fernando Carlos; Perea, H.; Wong, I.
- Ground-motion simulation in the Lower Tagus Valley BasinPublication . Borges, José Fernando; Bezzeghoud, Mourad; Caldeira, Bento; Carvalho, JoãoThroughout history, the Lower Tagus Valley (LTV) region has been shaken by several earthquakes, including some with moderate to large magnitudes and with sources located inside the basin, for example the 1344 (M6.0) and 1909 (M6.0) earthquakes. Previous simulations (Bezzeghoud et al. Natural Hazard 69: 1229–1245, 2011) have revealed strong amplification of the amplitude waves in the region, because of the effect of the low-velocity sediments that fill the basin. The model used in those simulations was updated in this work by including new high-resolution geophysical and geotechnical data available for the area (seismic reflection, aeromagnetic, gravimetric, deep wells, standard penetration tests, and geological data). To contribute to improved assessment of seismic hazard in the LTV, we simulated propagation of seismic waves produced by moderate earthquakes in a 3D heterogeneous medium by using elastic finite-difference wave propagation code. The method, successfully used by Grandin et al. (Geophys J Int 171: 1144–1161, 2007), involves evaluation of the seismic potential of known faults in the area studied and three-dimensional seismic ground motion modelling by use of finite difference methods. On the basis of this methodology, we calculated the ground motion for the April 23, 1909, Benavente (Portugal) earthquake (Mw = 6.0) in dense grid points, then computed the synthetic isoseismic map of the area by use of appropriate relationships between seismic intensity (MMI) and peak ground velocity (PGV). The synthetic results, in contrast with available macroseismic and instrumental data, enable validation of the source models proposed for the area, identification of the sources of historical earthquakes, and could also indicate which areas are more exposed to seismic ground motion.
- Velocity and structural model of Lower Tagus Basin (Portugal) derived from ambient seismic noise measurementsPublication . Borges, José Fernando; Torres, Ricardo Jorge Gomes; Silva, Hugo Gonçalves; Caldeira, Bento; Bezzeghoud, Mourad; Carvalho, João; Furtado, Augusto
- Velocity and structural model of the Lower Tagus Basin according to the study of environmental seismic noisePublication . Torres, Ricardo Jorge Gomes; Furtado, José Augusto; Silva, Hugo Gonçalves; Borges, José Fernando; Caldeira, Bento; Bezzeghoud, Mourad; Carvalho, João
- Macrossismicidade associada ao sismo de Arraiolos do dia 15 de janeiro de 2018 com M = 4,9 e eventuais implicações na geometria da ruturaPublication . Araujo, A.; Caldeira, Bento; Martins, Antonio; Borges, José Fernando; Moreira, Noel; Fonseca Araújo, Joana; Maia, Miguel; Vicente, S.; Afonso, P.; Espanhol, D.; Bezzeghoud, MouradRESUMO: Na segunda quinzena de janeiro de 2018 realizou-se um estudo da macrossismicidade associada ao sismo de Arraiolos de dia 15 de janeiro. No presente trabalho descreve-se a metodologia usada na recolha de informação, o tratamento dos dados e a sua representação na forma de mapa de intensidades. A distribuição geográfica das intensidades mostra um alongamento da isossista de intensidade IV na direção N-S e no sentido sul. Este alongamento poderá estar relacionado com uma variação lateral da atenuação, ou com um efeito de sítio. Outra hipótese, menos provável, é que este padrão se deva ao efeito de diretividade originado por uma rutura unilateral com propagação de norte para sul, ao longo de um plano do mecanismo focal. Esta possibilidade, conjugada com evidências para a existência de estruturas ativas WNW-ESE descritas em trabalhos anteriores, levanta a hipótese do designado “cluster sísmico de Arraiolos” estar associado a uma interseção de falhas ativas.
- Muon tomography with Resistive Plate Chambers for geological characterizationPublication . Sarmento, Raul; Castro, Alberto Blanco; Caldeira, Bento; Tomé, Bernardo; Loureiro, Custódio; Clemêncio, Filomena; Alexandre, Isabel; Costa, João; Matos, João Xavier; Saraiva, João; Silva, Jorge; Borges, José Fernando; Cazon, Lorenzo; Afonso, Luis; Lopes, Luís; Duarte, Magda; Pinto, Marco; Pimenta, Mário; Bezzeghoud, Mourad; Dobrilla, Paolo; Assis, Pedro; Teixeira, Pedro; Oliveira, R.; Andringa, Sofia; Pais, VanessaABSTRACT: Muon tomography is one of several fields of applied physics that have witnessed the successful use of particle detection based on Resistive Plate Chambers (RPC). In this work, we report on an innovative project concerning transmission muography for geological characterization. For this purpose, a muon telescope built of four RPC planes was mounted on an adjustable structure and the telescope's response to atmospheric muons was studied. Data acquisition campaigns took place at different locations for producing muographic images of the building of the Physics Department of the University of Coimbra, in Portugal. More recently, the detector was moved to an underground gallery of an old mine, where it is taking data that is being assessed in combination with the results from conventional geophysics techniques.
- Compilation of parameterized seismogenic sources in Iberia for the SHARE European-scale seismic source modelPublication . Nemser, Eliza; García-Mayordomo, J.; Cabral, João; Fonseca, J. F. B. D.; Martínez-Díaz, J. J.; Alfaro García, Pedro; Álvarez-Gómez, J. A.; Atakan, K.; Azañón Hernández, J. M.; Basili, R.; Besana-Ostman, G. M.; Bezzeghoud, Mourad; Borges, José Fernando; Silveira, A. Brum da; Lopes, Fernando Carlos; Carvalho, João P. F.; Dias, Ruben Pereira; Figueiredo, P. M.; García Fernández, M.; Giner-Robles, J. L.; González, A.; Gràcia, Eulália; Gutiérrez, F.; Insua Arévalo, J. M.; Jiménez, M. J.; Jiménez-Díaz, A.; Lafuente Tomás, P.; Lucha, P.; Madeira, J.; Martín González, F.; Masana, E.; Matias, L.; Moreno, X.; Ortuño, M.; Perea, H.; Pérez López, R.; Rodríguez Pascua, M. A.; Ruano, P.; Santanach, P.; Sanz de Galdeano, C.; Barroso, P. Silva; Silva, S.; Simón, J. L.; Terrinha, Pedro; Vilanova, Susana; Villamor, P.; Wong, I.
- Near-surface wave velocity structure of Faial (Azores - Portugal) Island for site effect studiesPublication . Borges, José Fernando; Neves, Samuel; Caldeira, Bento; Bezzeghoud, Mourad; Carvalho, João; Carvalho, Alexandra
- Low frequency modeling of ground motion in the Lower Tagus Valley BasinPublication . Borges, José Fernando; Torres, Ricardo Jorge Gomes; Caldeira, Bento; Silva, H.; Bezzeghoud, Mourad; Carvalho, João; Pinto, Carlos C.