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  • 1
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    Ground-Motion Simulations for the 1980 M 6.9 Irpinia Earthquake (Southern Italy) and Scenario Events (2011)
    Seismological Society of America (SSA)
    Details
    Publication Date: 2011-06-01
    Description: In this paper, we adopt three ground-motion simulation techniques (the stochastic finite-fault simulation code from Motazedian and Atkinson, 2005; the hybrid deterministic-stochastic approach with approximated Green's functions from Pacor et al., 2005; and the broadband hybrid integral-composite technique with full-wavefield Green's functions from Gallovi[c] and Broke[s]ova, 2007), with the aim of investigating the different performances in near-fault strong-motion modeling and prediction from past and future events. The test case is the 1980 M 6.9 Irpinia earthquake, the strongest event recorded in Italy in the last 30 years. First, we simulate the recorded strong-motion data and validate the model parameters by computing spectral acceleration and peak amplitude residual distributions. The validated model is then used to investigate the influence of site effects and to compute synthetic ground motions around the fault. Afterward, we simulate the expected ground motions from scenario events on the Irpinia fault, varying the hypocenters, the rupture velocities, and the slip distributions. We compare the median ground motions and related standard deviations from all scenario events with empirical ground-motion prediction equations (GMPEs). The synthetic median values are included in the median {+/-} 1 standard deviation of the considered GMPEs. Synthetic peak ground accelerations show median values smaller and with a faster decay with distance than the empirical ones. The synthetics total standard deviation is of the same order or smaller than the empirical one, and it shows considerable differences from one simulation technique to another. We decomposed the total standard deviation into its between-scenario and within-scenario components. The larger contribution to the total sigma comes from the latter, while the former is found to be smaller and in good agreement with empirical interevent variability.
    Print ISSN: 0037-1106
    Electronic ISSN: 1943-3573
    Topics: Geosciences , Physics
    Published by Seismological Society of America (SSA)
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  • 2
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    Campagna di Misure Sismiche nella conca Subequana (2012)
    Details
    Publication Date: 2017-04-04
    Description: A seguito del terremoto del 6 aprile 2009 che ha colpito la città de L’Aquila e la valle dell’Aterno, la Sezione di Milano-Pavia dell’Istituto Nazionale di Geofisica e Vulcanologia (INGV-MIPV) ha intrapreso una serie di attività strumentali che hanno riguardato l’installazione di stazioni sismiche temporanee e misure di noise sismico ambientale. INGV-MIPV è intervenuta sia durante le fasi di emergenza nei giorni seguenti il sisma, sia durante successive indagini utili a studi di microzonazione per la caratterizzazione sismica dei territori colpiti dal terremoto [Ameri et al., 2009]. Gli studi di effetti locali in alcuni paesi colpiti dal sisma e gli studi di sismotettonica in corso nell’area abruzzese hanno condotto alcune ricerche di INGV-MIPV a concentrarsi nella conca Subequana, bacino sedimentario a sud della media valle dell’Aterno. In tale area sono presenti piccoli centri urbani, dotati di centri storici antichi che hanno subito gravi danni all’edificato pur essendo già a notevole distanza dall’area epicentrale del sisma del 6 Aprile 2009 (circa 50 Km). Come indicato nel rapporto macrosismico redatto congiuntamente da INGV e il Dipartimento di Protezione Civile Nazionale [Galli e Camassi, 2009], i centri abitati della conca Subequana Castelvecchio Subequo, Goriano Sicoli e Castel di Ieri hanno subito un danno rispettivamente di grado 7.0, 7.0 e 6.5 della scala MCS. Castelvecchio Subequo è stato indicato nel rapporto macrosismico tra i paesi con possibili effetti di sito. Utilizzando strumentazione mobile è stata realizzata una campagna di misure di noise sismico ambientale che ha coperto l’area del bacino sedimentario della conca Subequana e l’abitato di Castelvecchio Subequo. Le misure effettuate sulla superficie del bacino sedimentario sono utili per indagare la risposta 1D del bacino, attraverso la tecnica di Nakamura [Nakamura, 1989] e per stimare la profondità del substrato roccioso. Inoltre, la serie di misure all’interno del centro storico di Castelvecchio Subequo può essere utilizzata per indagare alcuni aspetti della risposta sismica locale dovuti alla morfologia sulla quale è costruito il centro urbano. Una micro rete di monitoraggio di terremoti, composta da tre stazioni, è stata installata per ottenere ulteriori informazioni sulla risposta sismica locale del centro urbano, applicando le tecniche d’analisi con stazione di riferimento.
    Description: Istituto Nazionale di Geofisica e Vulcanologia
    Description: Published
    Description: 1.1. TTC - Monitoraggio sismico del territorio nazionale
    Description: open
    Keywords: noise sismico ; microtremori ; aquila ; subequana ; reti sismiche temporanee ; 04. Solid Earth::04.02. Exploration geophysics::04.02.06. Seismic methods ; 04. Solid Earth::04.02. Exploration geophysics::04.02.07. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: report
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  • 3
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    Testing the improvement of ShakeMaps using f inite-f ault models and synthetic seismograms (2011)
    Details
    Publication Date: 2017-04-04
    Description: ShakeMap package uses empirical ground motion prediction equations (GM PEs) to estimate the ground motion where recorded data are not available. Recorded and estimated values are then interpolated in order to produce a shaking map associated to the considered event. Anyway GMPEs account only for average characteristics of source and wave propagation processes. Within the framework of the DPC-INGV S3 project (2007-09), we evaluate whether the inclusion of directivity effects in GMPEs (companion paper Spagnuolo et al., 2010) or the use of synthetic seismograms from finite-fault rupture models may improve the ShakeMap evaluation. An advantage of using simulated motions from kinematic rupture models is that source effects, as rupture directivity, are directly included in the synthetics. This is particularly interesting in Italy where the regional GMPEs, based on a few number of near-source records for moderate-to-large earthquakes, are not reliable for estimating ground motion in the vicinity of the source. In this work we investigated how and if the synthetic seismograms generated with finite-fault models can be used in place of (or in addition to) GMPEs within the ShakeMap methodology. We assumed a description of the rupture model with gradually increasing details, from a simple point source to a kinematic rupture history obtained from inversion of strong-motion data. According to the available information synthetic seismograms are calculated with methods that account for the different degree of approximation in source properties. We chose the M w 6.9 2008 Iwate-M iyagi (Japan) earthquake as a case study. This earthquake has been recorded by a very large number of stations and the corresponding ShakeMap relies almost totally on the recorded ground motions. Starting from this ideal case, we removed a number of stations in order to evaluate the deviations from the reference map and the sensitivity of the map to the number of stations used. The removed data are then substituted with synthetic values calculated assuming different source approximations, and the resulting maps are compared to the original ones (containing observed data only). The use of synthetic seismograms computed for finite-fault rupture models produces, in general, an improvement of the calculated ShakeMaps, especially when synthetics are used to integrate real data. When real data are not available and ShakeMap is estimated using GMPEs only, the improvement adding simulated values depends on the considered strong-motion parameters.
    Description: Published
    Description: Montpellier , France
    Description: 4.1. Metodologie sismologiche per l'ingegneria sismica
    Description: open
    Keywords: Shakemaps ; synthetic seismograms ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Poster session
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