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Smerzini, Chiara
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Smerzini, Chiara
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- PublicationOpen AccessCharacteristics of strong ground motions from the L’Aquila (Mw = 6.3) earthquake and its strongest aftershocks(2011-09)
; ; ; ; ; ; ; ;Pacor, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Milano-Pavia, Milano, Italia ;Ameri, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Milano-Pavia, Milano, Italia ;Bindi, D.; GFZ, Helmholtz-Zentrum 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 ;Paolucci, R.; Politecnico di Milano ;Smerzini, C.; Politecnico di Milano; ; ; ; ; ; Strong motion data during the L’Aquila seismic sequence, were mainly recorded by the Italian accelerometric network (Rete Accelerometrica Nazionale, RAN), operated by the Department of Civil Protection (DPC). Several records were obtained also by a temporary network installed the day after the mainshock by the Istituto Nazionale di Geofisica e Vulcanologia (INGV). The L’Aquila earthquake is the third strongest seismic event producing strong-motion records in Italy, after the Irpinia (1980, Mw 6.9) and Friuli (1976, Mw 6.4) earthquakes. This event, together with its largest aftershocks (Mw > 4.0) provided a unique strong-motion data set in Italy, especially due to the amount and intensity of near-fault records. The data set included in the Italian strong motion database, ITACA, consists of about 300 digital accelerograms (270 of which belonging to RAN), with a very good signal-to-noise ratio, recorded by about 70 stations, installed on different site conditions at distances ranging from 0 to 300 km. The national and international relevance of this data set is enhanced by its contribution to filling gaps in the magnitude-distance distribution of worldwide strong motion records, especially for normal-fault earthquakes. Near-fault records were obtained by (i) an array of 6 stations installed by DPC in 2001 in the Aterno Valley to study seismic site effects; (ii) station AQK close to downtown L’Aquila; (iii) station AQU, belonging to the broad-band Mednet network, located in the L’Aquila historic castle; (iv) the stations of the INGV temporary network, installed in the epicentral region one day after the mainshock. These stations are located less than 5 km from the mainshock epicenter and are inside the surface projection of the fault rupture. This work presents an overview of the main features of seismic ground shaking during the L’Aquila sequence, referring to records of the mainshock and of the two strongest aftershocks. The dependence of the strong-motion parameters on distance, azimuth and site conditions as well as the characteristics of near-fault strong-motion records are discussed225 300 - PublicationOpen AccessSpectral elements numerical simulation of the 2009 L’Aquila earthquake on a detailed reconstructed domain(2022)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ;; ; ; ; ; ; ; ;In this paper we simulate the earthquake that hit the city of L'Aquila on the 6th of April 2009 using SPEED (SPectral Elements in Elastodynamics with Discontinuous Galerkin), an open-source code able to simulate the propagation of seismic waves in complex three-dimensional (3D) domains. Our model includes an accurate 3D recon- struction of the Quaternary deposits, according to the most up-to-date data obtained from the Microzonation studies in Central Italy and a detailed model of the topography incorporated using a newly developed tool (May et al. 2021). The sensitivity of our results with respect to dfferent kinematic seismic sources is inves- tigated. The results obtained are in good agreement with the recordings at the available seismic stations at epicentral distances within a range of 20km. Finally, a blind source prediction scenario application shows a reasonably good agreement between simulations and recordings can be obtained by simulating stochastic rupture realizations with basic input data. These results, although limited to nine simulated scenarios, demonstrate that it is possible to obtain a satisfactory reconstruction of a ground shaking scenario employing a stochastic source constrained on a limited amount of ex-ante information. A similar approach can be used to model future and past earthquakes for which little or no information is typically available, with potential relevant implications for seismic risk assessment.136 26 - PublicationOpen AccessThe 6 April 2009, Mw 6.3, L’Aquila (Central Italy) earthquake: strong-motion observations(2009-11)
; ; ; ; ; ; ; ; ; ; ; ;Ameri, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Milano-Pavia, Milano, Italia ;Massa, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Milano-Pavia, Milano, Italia ;Bindi, D.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Milano-Pavia, Milano, Italia ;D'Alema, E.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Milano-Pavia, Milano, Italia ;Gorini, A.; DPC ;Luzi, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Milano-Pavia, Milano, Italia ;Marzorati, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Milano-Pavia, Milano, Italia ;Pacor, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Milano-Pavia, Milano, Italia ;Paolucci, R.; POLIMI ;Puglia, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Milano-Pavia, Milano, Italia ;Smerzini, C.; POLIMI; ; ; ; ; ; ; ; ; ; On 6 April 2009, 01:32:40 UTC, an Mw 6.3 earthquake occurred in the Abruzzo region (central Italy), close to L’Aquila, a town of 68,500 inhabitants. About 300 people died because of the collapse of many residential and public build¬ings, and damage was widespread in L’Aquila and its neighbor¬ing municipalities. The earthquake occurred at 9.5 km depth along a NW-SW normal fault with SW dip, located below the city of L’Aquila (Istituto Nazionale di Geofisica e Vulcanologia [INGV] 2009a). The maximum observed intensity is IX–X in the MCS scale and the most relevant damages are distributed in the NW-SE direc¬tion, with evident predominance toward the southeast (Istituto Nazionale di Geofisica e Vulcanologia 2009b). This event rep¬resents the third largest earthquake recorded by strong-motion instruments in Italy, after the 1980 Mw 6.9 Irpinia and the 1976 Mw 6.4 Friuli earthquakes (Luzi et al. 2008). The mainshock was followed by seven aftershocks of moment magnitude larger than or equal to 5, the two stron¬gest of which occurred on April 7 (Mw = 5.6) and April 9 (Mw = 5.4). The mainshock and its aftershocks have been recorded by several digital stations of the Italian strong-motion network (Rete Accelerometrica Nazionale, R AN), operated by the Italian Department of Civil Protection (DPC); by the Italian seismometric network (Rete Sismometrica Nazionale, operated by INGV-Centro Nazionale Terremoti (CNT); http://cnt. rm.ingv.it); and by a temporary strong-motion array installed by the INGV Sezione di Milano-Pavia (MI-PV; http://www. mi.ingv.it). A total of 56 three-component strong-motion record¬ings were obtained within 280 km for the mainshock, with 23 being within 100 km of the epicenter. Horizontal peak ground motions in the near-fault region range from 327 to 646 cm/sec2, the latter representing one of the highest values recorded in Italy. This strong-motion data set, consisting of 954 waveforms from Mw > 4.0 events, is unique in Italy because it is entirely digital and includes observations from near-fault dis¬tances to some hundred kilometers away. The data set has been integrated in the new Italian strong-motion database ITACA (ITalian ACcelerometric Archive), available at http://itaca. mi.ingv.it. This paper provides an overview of the strong-motion recordings of the mainshock and the two strongest aftershocks with preliminary analyses of different strong-motion param¬eters as a function of distance, azimuth, and site conditions.450 1004 - PublicationOpen AccessAn empirical model for the vertical‐to‐horizontal spectral ratios for Italy(2021)
; ; ; ; ; ; ; This work presents a novel empirical Ground Motion prediction Model (GMM) for vertical-to-horizontal (VH) response spectral amplitudes up to 10 s, peak ground acceleration and velocity for shallow crustal earthquakes in Italy. Being calibrated on the most up-to-date strong motion dataset for Italian crustal earthquakes (ITA18), the model is consistent with the ITA18 GMM for the horizontal ground motion. This property makes the model useful in probabilistic seismic hazard assessment for Italy to derive compatible vertical and horizontal response spectra. To account for the increase of VH ratios in the proximity of the seismic source, an adjustment term is introduced to improve the prediction capability of the model in near-source conditions, relying on the worldwide NEar-Source Strong motion dataset (NESS). The proposed model uses a simple functional form restricted to a limited number of predictor variables, namely, magnitude, source-to-site distance, focal mechanism, and site effects, and the variability associated with both VH and V models is provided.177 30 - PublicationOpen AccessTopographic amplification from recorded earthquake data and numerical simulations(2012-09-24)
; ; ; ; ; ;Cauzzi, Carlo; Swiss Seismological Service (SED-ETHZ), Zürich, Switzerland ;Fäh, Donat; Swiss Seismological Service (SED-ETHZ), Zürich, Switzerland ;Pessina, Vera; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Milano-Pavia, Milano, Italia ;Faccioli, Ezio; Department of Structural Engineering, Politecnico di Milano, Italy ;Smerzini, Chiara; Department of Structural Engineering, Politecnico di Milano, Italy; ; ; ; With the aim of contributing to the refinement of the next generation of tools for seismic hazard analyses, we present here an attempt at including topographic amplification factors in GMPEs, thus broadening the traditional options for site effects. With a view to critically discuss and complement with new data the approach of Cauzzi et al. (2010) and Paolucci (2002), information from additional numerical models including crustal layering are taken into account. The indications obtained from the numerical simulations are cross-checked against and consolidated by analyses of the residuals of a selection of strong- and weak-motion observations on topographic reliefs in Italy and Switzerland (carefully selected via GIS) with respect to a set of largely used GMPEs.213 234