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Second University of Naples
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- PublicationOpen AccessSupport Vector Machines and MLP for automatic classification of seismic signals at Stromboli volcano(2009-05-28)
; ; ; ; ; ;GIACCO, F.; Department of Physics, University of Salerno, Italy ;ESPOSITO, A.M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia ;SCARPETTA, S.; Department of Physics, University of Salerno, Italy; INFN and INFM CNISM, Salerno, Italy; Institute for Advanced Scientific Studies, Vietri sul Mare, Italy, Germany ;GIUDICEPIETRO, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia ;MARINARO, M.; Department of Physics, University of Salerno, Italy; INFN and INFM CNISM, Salerno, Italy; Institute for Advanced Scientific Studies, Vietri sul Mare, Italy, Germany; ; ; ; ; ; ; ;Apolloni, B.; Università degli Studi di Milano, Dipartimento di Scienze dell’Informazione,Milano, Italy ;Bassis, S.; Università degli Studi di Milano, Dipartimento di Scienze dell’Informazione,Milano, Italy ;Morabito, C.F.; Università di Reggio Calabria, IMET, Loc. Feo di Vito,Reggio Calabria, Italy; ; We applied and compared two supervised pattern recognition techniques, namely the Multilayer Perceptron (MLP) and Support Vector Machine (SVM), to classify seismic signals recorded on Stromboli volcano. The available data are firstly preprocessed in order to obtain a compact representation of the raw seismic signals. We extract from data spectral and temporal information so that each input vector is made up of 71 components, containing both spectral and temporal information extracted from the early signal. We implemented two classification strategies to discriminate three different seismic events: landslide, explosion-quake, and volcanic microtremor signals. The first method is a two-layer MLP network, with a Cross-Entropy error function and logistic activation function for the output units. The second method is a Support Vector Machine, whose multi-class setting is accomplished through a 1vsAll architecture with gaussian kernel. The experiments show that although the MLP produces very good results, the SVM accuracy is always higher, both in term of best performance, 99.5%, and average performance, 98.8%, obtained with different sampling permutations of training and test sets187 2554 - PublicationRestrictedMechanical origin of aftershocks(2015)
; ; ; ; ; ; ; ; ; Aftershocks are the most striking evidence of earthquake interactions and the physical mechanisms at the origin of their occurrence are still intensively debated. Novel insights stem from recent results on the in influence of the faulting style on the aftershock organisation in magnitude and time. Our study shows that the size of the aftershock zone depends on the fault geometry. We find that positive correlations among parameters controlling aftershock occurrence in time, energy and space are a stable feature of seismicity independently of magnitude range and geographic areas. We explain the ensemble of experimental findings by means of a description of the Earth Crust as an heterogeneous elastic medium coupled with a Maxwell viscoelastic asthenosphere. Our results show that heterogeneous stress distribution in an elastic layer combined with a coupling to a viscous flow are sufficient ingredients to describe the physics of aftershock triggering.69 1 - PublicationRestrictedParameter Estimation in the ETAS Model: Approximations and Novel Methods(2014)
; ; ; ; ; ;Lippiello, E.; Second University of Naples ;Giacco, F.; Second University of Naples ;De Arcangelis, L.; Second University of Naples ;Marzocchi, W.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Godano, C.; Second University of Naples; ; ; ; Branching processes provide an accurate description of earthquake occurrence in the short term (days to a few weeks). Yet, the implementation of these models is not usually straightforward because of the difficulties in estimating the parameters. Indeed, log-likelihood estimation involves a spatial integral that cannot be analytically evaluated and is difficult to implement in numerical codes. Here we present a novel technique that allows for an accurate, stable, and relatively fast param- eter inversion procedure. We study the efficiency of this technique using synthetic epidemic-type aftershock sequence catalogs with a set of parameters known a priori. Results show the efficiency of the novel technique and illustrate the limits of recently proposed approximations147 26 - PublicationRestrictedStatistical Features of Foreshocks in Instrumental and ETAS Catalogs(2017)
; ; ; ; ; ; ; ; ; We study the spatial distribution of earthquakes in temporal intervals before and after the occurrence of large shocks (mainshocks) in the magnitude range m [2 5] for four different regional catalogs. We find that the spatial organization of pre-shock seismicity depends on the mainshock magnitude and is independent of the lower magnitude threshold. These properties are found to be a stable feature of regional catalogs and cannot be reproduced by Epidemic Type Aftershock Sequence models. Our findings suggest that the area fractured during the mainshock is encoded in the foreshock spatial organization and, therefore, enhance the prognostic value of foreshocks.50 4