12 documents found, page 1 of 2
The Portuguese National Seismic Network —Products and Services
Carrilho, F.; Custodio, S.; Bezzeghoud, M.; Oliveira, C. S.; Marreiros, C.; Vales, D.; Alves, P.; Pena, A.; Madureira, G.; Escuer, M.; Silveira, G.Portugal, located in the southwest region of the Eurasian plate, has been affected by several destructive earthquakes throughout its history, the most well-known being the 1755 Great Lisbon earthquake. The seismicity of the territory, both in the mainland and in the Azores and Madeira islands, has prompted the continuous development of seis- mic monitoring, from the first known macroseismic inquiry, following t...
Ambient Noise Recorded by a Dense Broadband Seismic Deployment in Western Iberia
Custodio, S.; Dias, N. A.; Caldeira, B.; Carrilho, F.; Carvalho, Sara; Corela, C.; Diaz, J.; Narciso, J.; Madureira, G.; Matias, L.; Haberland, C.The West Iberia Lithosphere and Asthenosphere Structure (WILAS) project densely covered Portugal with broadband seismic stations for 2 yrs. Here we provide an overview of the deployment, and we characterize the network ambient noise and its sources. After explaining quality control, which includes the assessment of sensor orientation, we characterize the background noise in the short‐period (SP), microseismic, ...
Seismic detection using support vector machines
Ruano, Antonio; Madureira, G.; Barros, O.; Khosravani, Hamid Reza; Ruano, M. Graça; Ferreira, P. M.This study describes research to design a seismic detection system to act at the level of a seismic station, providing a similar role to that of STA/LTA ratio-based detection algorithms. In a first step, Multi-Layer Perceptrons (MLPs) and Support Vector Machines (SVMs), trained in supervised mode, were tested. The sample data consisted of 2903 patterns extracted from records of the PVAQ station, one of the seis...
On-line operation of an intelligent seismic detector
Madureira, G.; Ruano, Antonio; Ruano, M. GraçaThis study describes the on-line operation of a seismic detection system to act at the level of a seismic station providing similar role to that of a STA /LTA ratio-based detection algorithms. The intelligent detector is a Support Vector Machine (SVM), trained with data consisting of 2903 patterns extracted from records of the PVAQ station, one of the seismographic network's stations of the Institute of Meteoro...
On-line operation of an intelligent seismic detector
Madureira, G.; Ruano, Antonio; Ruano, M. GraçaThis study describes the on-line operation of a seismic detection system to act at the level of a seismic station providing similar role to that of a STA / LTA ratio- based detection algorithms. The intelligent detector is a Support Vector Machine (SVM), trained with data consisting of 2903 patterns extracted from records of the PVAQ station, one of the seismographic network’s stations of the Institute of Meteo...
A support vector machine seismic detector for early-warning applications
Ruano, Antonio; Madureira, G.; Barros, O.; Khosravani, Hamid Reza; Ruano, M. Graça; Ferreira, P. M.This paper extends a Support Vector Machine (SVM) approach for the detection of seismic events, at the level of a seismic station. In previous works, it was shown that this approach produced excellent results, in terms of the Recall and Specificity measures, whether applied off-line or in a continuous scheme. The drawback was the time taken for achieving the detection, too large to be applied in a Early-Warning...
Seismic Tomography of the Algarve Crust: Previous studies, Campaign and first data
Caldeira, Bento; Bezzeghoud, Mourad; Borges, José F.; Matias, L.; Rocha, João P.; Madureira, G.; Araújo, A.; Corela, C.; Carrilho, F.The Local Earthquake Tomography of Algarve (Portugal), the main objective of this project, will permit produces detailed images of the Algarve crust lithosphere and the mantle in terms ofseismic body waves velocity variations (Teleseismic Tomography) or absolutes velocities (Local Earthquake Tomography, LET). Through the LET of Monchique-Portimiio and Louli-Faro we expect to obtain a more detailed understanding...
Active learning in the detection of seismic events using artificial neural netw...
Ruano, Antonio; Madureira, G.In previous studies, a Support Vector Machine (SVM) was trained with a universe of data consisting of 3284 samples, which was divided into two sets, for training and validation, with approximately the same number of elements. Then put into practice a strategy of active learning having been obtained at the end an optimum detector for those sets. At this stage the objective was to apply the above active learning ...
A neural network seismic detector
Madureira, G.; Ruano, AntonioAbstract: This experimental study focuses on a detection system at the seismic station level that should have a similar role to the detection algorithms based on the ratio STA/LTA. We tested two types of neural network: Multi-Layer Perceptrons and Support Vector Machines, trained in supervised mode. The universe of data consisted of 2903 patterns extracted from records of the PVAQ station, of the seismography n...
Detecção de eventos sísmicos utilizando redes neuronais artificiais
Madureira, G.; Ruano, AntonioThis experimental study focuses on a detection system at the seismic station level that should have a similar role to the detection algorithms based on the ratio STA / LTA. We tested two types of neural network: Multi-Layer Perceptrons and Support Vector Machines, trained in supervised mode. The universe of data consisted of 2903 patterns extracted from records of the PVAQ station, of the seismography network o...