Options
Traversa, Paola
Loading...
Preferred name
Traversa, Paola
4 results
Now showing 1 - 4 of 4
- PublicationOpen AccessComparisons among the five ground-motion models developed using RESORCE for the prediction of response spectral accelerations due to earthquakes in Europe and the Middle East(2014-02)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;Douglas, J.; BRGM, Orléans, France ;Akkar, S.; Middle East Technical University, Ankara, Turkey ;Ameri, G.; FUGRO-Geoter, Auriol, France. ;Bard, P.; ISTerre, Grenoble, France ;Bindi, D.; GFZ, Potsdam, Germany ;Bommer, J.; Imperial College London, United Kingdom ;Bora, S. S.; Inst. Erd- und Umweltwissesnschaften, Universitaet Potsdam, Germany ;Cotton, F.; ISTerre, Grenoble, France ;Derras, B.; ISTerre, Grenoble, France ;Hermkes, M.; Inst. Erd- und Umweltwissesnschaften, Universitaet Potsdam, Germany ;Kuehn, N. M.; Inst. Erd- und Umweltwissesnschaften, Universitaet Potsdam, Germany ;Luzi, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Milano-Pavia, Milano, Italia ;Massa, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Milano-Pavia, Milano, Italia ;Pacor, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Milano-Pavia, Milano, Italia ;Riggelsen, C.; Inst. Erd- und Umweltwissesnschaften, Universitaet Potsdam, Germany ;Sandikkaya, M. A.; Middle East Technical University, Ankara, Turkey ;Scherbaum, F.; Inst. Erd- und Umweltwissesnschaften, Universitaet Potsdam, Germany ;Stafford, P.; Imperial College London, United Kingdom ;Traversa, P.; EDF, Aix en Provence, France; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; This article presents comparisons among the five ground-motion models described in other articles within this special issue, in terms of data selection criteria, characteristics of the models and predicted peak ground and response spectral accelerations. Comparisons are also made with predictions from the Next Generation Attenuation (NGA) models to which the models presented here have similarities (e.g. a common master database has been used) but also differences (e.g. some models in this issue are nonparametric). As a result of the differing data selection criteria and derivation techniques the predicted median ground motions show considerable differences (up to a factor of two for certain scenarios), particularly for magnitudes and distances close to or beyond the range of the available observations. The predicted influence of style-of-faulting shows much variation among models whereas site amplification factors are more similar, with peak amplification at around 1s. These differences are greater than those among predictions from the NGA models. The models for aleatory variability (sigma), however, are similar and suggest that ground-motion variability from this region is slightly higher than that predicted by the NGA models, based primarily on data from California and Taiwan.214 263 - PublicationOpen AccessMethodology to identify the reference rock sites in regions of medium-to-high seismicity: an application in Central Italy(2020)
; ; ; ; ; ; ; ; ; To evaluate the site response using both empirical approaches (e.g. standard spectral ratio, ground motion models (GMMs), generalized inversion techniques, etc.) and numerical 1-D/2-D analyses, the definition of the reference motion, that is the ground motion recorded at stations unaffected by site-effects due to topographic, stratigraphic or basin effects, is needed. The main objective of this work is to define a robust strategy to identify the seismic stations that can be considered as reference rock sites, using six proxies for the site response: three proxies are related to the analysis of geophysical and seismological data (the repeatable site term from the residual analysis, the resonance frequencies from horizontal-to-vertical spectral ratios on noise or earthquake signals, the average shear wave velocity in the first 30 m); the remaining ones concern geomorphological and installation features (outcropping rocks or stiff soils, flat topography and absence of interaction with structures). We introduce a weighting scheme to take into account the availability and the quality of the site information, as well as the fulfillment of the criterion associated to each proxy. We also introduce a hierarchical index, to take into account the relevance of the proposed proxies in the description of the site effects, and an acceptance threshold for reference rock sites identification. The procedure is applied on a very large data set, composed by accelerometric and velocimetric waveforms, recorded in Central Italy in the period 2008–2018. This data set is composed by more than 30 000 waveforms relative to 450 earthquakes in the magnitude range 3.2–6.5 and recorded by more than 450 stations. A total of 36 out of 133 candidate stations are identified as reference sites: the majority of them are installed on rock with flat topography, but this condition is not sufficient to guarantee the absence of amplifications, especially at high frequencies. Seismological analyses are necessary to exclude stations affected by resonances. We test the impact of using these sites by calibrating a GMMs. The results show that for reference rock sites the median predictions are reduced down to about 45 per cent at short periods in comparison to the generic rock motions.352 28 - PublicationOpen AccessThe 2009 L'Aquila (central Italy) seismic sequence(2011)
; ; ; ; ; ; ; ; ; ; ;Chiaraluce, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Chiarabba, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;De Gori, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Di Stefano, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Improta, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Piccinini, D.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Schlagenhauf, A. ;Traversa, P. ;Valoroso, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Voisin, C.; ; ; ; ; ; ; ;; On April 6 (01:32 UTC) 2009 a MW 6.1 normal faulting earthquake struck the axial area of the Abruzzo region in central Italy. The earthquake heavily damaged the city of L’Aquila and its surroundings, causing 308 casualties, 70,000 evacuees and incalculable losses to the cultural heritage. We present the geometry of the fault system composed of two main normal fault planes, reconstructed by means of seismicity distribution: almost 3000 events with ML≥1.9 occurred in the area during 2009. The events have been located with a 1D velocity model we computed for the area by using data of the seismic sequence. The mainshock, located at around a 9.3 km depth beneath the town of L’Aquila, activated a 50° (+/- 3) SW-dipping and ~135° NW-trending normal fault with a length of about 16 km. The aftershocks activated the whole 10 km of the upper crust up to the surface. The geometry of the fault is coherent with the mapped San Demetrio-Paganica and Mt. Stabiata normal faults. The whole normal fault system that reached about 40 km of length by the end of December in the NW-trending direction, was activated within the first few days of the sequence when most of the energetic events occurred. The main shock fault plane was activated by a foreshock sequence that culminated with a MW 4.0 on March 30 (13:38 UTC), showing extensional kinematics with a minor left lateral component. The second major structure, located to the north close to Campotosto village, is controlled by an MW 5.0 event, which occurred on the same day of the main shock (April 6 at 23:15 UTC), and by an MW 5.2 event (April 9 at 00:53 UTC). The fault plane shows a shallower dip angle with respect to the main fault plane, of about 35° with a tendency to flattening towards the deepest portion. Due to the lack of seismicity above a 5 km depth, the connection between this structure and the mapped Monti della Laga fault is not straightforward. This northern segment is recognisable for about 12-14 km of length, always NW-trending and forming a right lateral step with the main fault plane. The result is a en-echelon system overlapping for about 6 km. The seismicity pattern also highlights the activation of numerous minor normal fault segments within the whole fault system. The deepest is located at around a 13-15 km depth, south of the L’Aquila mainshock, and it seems to be antithetic to the main fault plane.411 507 - PublicationRestrictedGeneric-To-Reference Rock Scaling Factors for Seismic Ground Motion in Italy(2022)
; ; ; ; ; ; ; ; ; In this article, we apply the reference-rock identification method (RRIM; Lanzano et al., 2020) to the ITalian ACcelerometric Archive, which includes more than 1600 recording stations in Italy and in the neighboring countries, with different levels of site characterization. The RRIM is based on the identification and the evaluation of site parameters representing the reference site conditions (Steidl et al., 1996) and the construction of the scoring scheme to classify the candidate stations. Given the large number of sites, the preselection of can- didates is performed via residual analysis, selecting those characterized by flat site response and amplitude similar or lower than the one for the generic rock (average shear-wave veloc- ity in the uppermost 30 m, V S30 800 m= s). The main results of this study are: (1) a list of reference rock sites in Italy, with an associated score; (2) a scenario-independent generic-to- reference rock corrective factor for the ground-motion model for shallow active crustal events in Italy (ITA18; Lanzano, Luzi, et al., 2019); (3) a model for the generic-to-reference rockcorrectivefactor,parametrizedintermsofVS30 andκ0,thatis,thehigh-frequencydecay parameter (Anderson and Hough, 1984). A collateral product is a set of coefficients for the prediction of 81 ordinates of the Fourier amplitude spectra (FAS) in the frequency interval 0.1–30 Hz, calibrated with the same dataset and functional form of ITA18 for acceleration response spectra (SA). The application of RRIM allowed us to identify 116 stations with aver- age measured V S30 ∼ 900 m= s. The corrective factor allows to scale both SA and FAS spectra, and has a significant effect at high frequencies, reducing the ground motion by up to a factor 1.7 at f = 10 Hz. The introduction of κ0 in the corrective term modeling is effective from 2 Hz onward and results in a reduction of variability at high frequencies (f > 10 Hz).260 58