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  • 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous  (21)
  • Carbon cycle
  • Seismological Society of America  (20)
  • Nature Publishing Group
  • MDPI Publishing
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  • 1
    Publikationsdatum: 2022-05-26
    Beschreibung: © The Author(s), 2018. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Nature Communications 9 (2018): 121, doi:10.1038/s41467-017-02504-1.
    Beschreibung: Sediments in deep ocean trenches may contain crucial information on past earthquake history and constitute important sites of carbon burial. Here we present 14C data on bulk organic carbon (OC) and its thermal decomposition fractions produced by ramped pyrolysis/oxidation for a core retrieved from the 〉7.5 km-deep Japan Trench. High-resolution 14C measurements, coupled with distinctive thermogram characteristics of OC, reveal hemipelagic sedimentation interrupted by episodic deposition of pre-aged OC in the trench. Low δ13C values and diverse 14C ages of thermal fractions imply that the latter material originates from the adjacent margin, and the co-occurrence of pre-aged OC with intervals corresponding to known earthquake events implies tectonically triggered, gravity-flow-driven supply. We show that 14C ages of thermal fractions can yield valuable chronological constraints on sedimentary sequences. Our findings shed new light on links between tectonically driven sedimentological processes and marine carbon cycling, with implications for carbon dynamics in hadal environments.
    Beschreibung: This study is supported by Doc.Mobility Fellowship (P1EZP2_159064) (R.B.) from the Swiss National Science Foundation (SNSF). This work is also supported by SNF “CAPS-LOCK” project 200021_140850 (T.I.E.), by SNSF grant (133481) (M.S.), and Austrian Science Foundation (P 29678-N28) (M.S.).
    Schlagwort(e): Carbon cycle ; Sedimentology
    Repository-Name: Woods Hole Open Access Server
    Materialart: Article
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  • 2
    Publikationsdatum: 2017-04-04
    Beschreibung: Earthquake-rotated objects (EROs) have been observed and described for centuries (e.g., Hoffmann, 1838; Mallet, 1862; Reid, 1910). Several theories about the rotating mechanisms have been developed. Kozák (2006) classified rotating effects as those caused by a deviation between the projection of the center of gravity into the contact plane and the point of strongest adhesion (Rot1) and those due to subsequent arrival of ground-motion phases from different directions (Rot2). The EROs found in the literature include parts of buildings, such as chimneys, monuments, tombstones, and columns, often described with great care and in detail by early earthquake reports (Mallet, 1862) or still accessible (Boschi et al., 1995). However, in most cases rotational effects are observed on vertically oriented objects such as gravestones, tall monuments, and single columns (Kozák, 2009). Although earthquake- toppled objects (ETOs) allow the determination of minimum ground-motion thresholds which caused the toppling (Kamai and Hatzor 2008; Hinzen, 2010, 2012), EROs and earthquake-deformed objects (EDOs) present the chance to make a more detailed back calculation of the causative ground motion (Yegian et al., 1994; Lee et al., 2009; Hinzen et al., 2010; Hough et al., 2012). Numerous EROs were observed and documented during the 2009 L’Aquila earthquake in central Italy. Cucci and Tertulliani (2011) and Castellano et al. (2012) showed a correlation between the occurrence of EROs in the mesoseismal zone, the fault orientation, and the site conditions. Some of the simply structured and vertically oriented objects mapped by Cucci et al. (2011) and Cucci and Tertulliani (2011) offer the opportunity to use local strong-motion records to test different hypotheses about the mechanisms that caused the rotation. A main question in this context is whether near-field rotational components of ground motion are necessary to rotate the studied objects or whether 3D purely translational ground motions are sufficient to explain the observations. In this study, we use discrete-element models of EROs that are based on laser scans to study the dynamic behavior of the EROs and rotations induced by translation ground motions and uneven foundations.
    Beschreibung: Published
    Beschreibung: 745-751
    Beschreibung: 3T. Pericolosità sismica e contributo alla definizione del rischio
    Beschreibung: JCR Journal
    Beschreibung: restricted
    Schlagwort(e): earthquake rotations ; L'Aquila 2009 earthquake ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 3
    Publikationsdatum: 2017-04-04
    Beschreibung: In the past few years, the awareness that earthquake-induced rotational effects can be significant in the near-fault region of an earthquake, and the consequent implications in seismic engineering, has gained rotational seismology a strong recovery in the attention of the scientific community. Impulses came from direct observations as well as numerical simulations, and special volumes related to this topic have been recently published by the Bulletin of the Seismological Society of America (Lee et al., 2009) and by the Journal of Seismology (Igel et al., 2012). In particular, some of the most recent papers on this subject addressed the earthquake-rotated objects (EROs hereinafter), considering the possible contribution to EROs occurrence from true rotational motion and/or translational motion (Kozák, 2006, 2009; Yang et al., 2010; Hinzen, 2012), the geometry of the structure (Mucciarelli et al., 2011), the clockwise/ counterclockwise (CW/CCW hereinafter) sense of rotation (Yegian et al., 1994), and the geological conditions at the site (Cucci and Tertulliani, 2011; Castellano et al., 2012). The renewed attention to earthquake-induced rotations allowed the collection of a significant dataset of EROs following the Mw 6.3 2009 L’Aquila (Central Italy) event (see Cucci et al., 2011 for a complete description of the dataset); this kind of data collection is a sound starting point for subsequent quantitative analyses of the data. In this paper, we present a newⒺdataset of EROs (available in the electronic supplement to this paper) originated by the Emilia seismic sequence, which occurred in northern Italy in 2012. The main aim of this study is to verify whether and how the distribution of the 2012 EROs is influenced by some geophysical observables (epicentral distance, intensity, directivity, lithology, etc.), in a geomorphological and seismological context completely different from that of 2009 L’Aquila.
    Beschreibung: Published
    Beschreibung: 973-981
    Beschreibung: 3T. Pericolosità sismica e contributo alla definizione del rischio
    Beschreibung: JCR Journal
    Beschreibung: restricted
    Schlagwort(e): earthquake rotations ; Emilia 2012 earthquakes ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 4
    Publikationsdatum: 2020-02-24
    Beschreibung: Accurate earthquake locations are crucial for investigating seismogenic processes, as well as for applications like verifying compliance to the Comprehensive Test Ban Treaty. Earthquake location accuracy is related to the degree of knowledge about the 3-D structure of seismic wave velocity in the Earth. It is well known that modeling errors of calculated travel times may have the effect of shifting the computed epicenters far from the real locations by a distance even larger than the size of the statistical error ellipses, regardless of the accuracy in picking seismic phase arrivals. In the present study, we develop a method of seismic location based on a set of well located events recorded by the dense national seismic network in a seismically active region of central Japan. We show that mislocations of the order of 10-20 km affecting the epicenters calculated from a global seismic network and using the standard IASPEI91 travel times can be effectively removed by applying station-source-specific corrections. The results show a clear correlation of the travel time residuals with the subduction structure beneath Japan.
    Beschreibung: Published
    Beschreibung: 225-236
    Beschreibung: 2T. Tettonica attiva
    Beschreibung: JCR Journal
    Beschreibung: restricted
    Schlagwort(e): Travel-time correction ; Teleseimic location ; Seismic monitoring and test-ban treaty verification. ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 5
    Publikationsdatum: 2021-06-25
    Beschreibung: We adopt a spectral-element method (SEM) to perform numerical simulations of the complex wavefield generated by the 6 April 2009 Mw 6.3 L’Aquila earthquake in central Italy. The mainshock is represented by a finite-fault solution obtained by inverting strong-motion and Global Positioning System data, testing both 1D and 3D wavespeed models for central Italy. Surface topography, attenuation, and the Moho discontinuity are also accommodated. Including these complexities is essential to accurately simulate seismic-wave propagation. Three-component synthetic waveforms are compared to corresponding velocimeter and strong-motion recordings. The results show a favorable match between data and synthetics up to ∼0:5 Hz in a 200 km × 200 km × 60 km model volume, capturing features mainly related to topography or low-wavespeed basins. We construct synthetic peak ground velocity maps that, for the 3D model, are in good agreement with observations, thus providing valuable information for seismic-hazard assessment. Exploiting the SEM in combination with an adjoint method, we calculate finite-frequency kernels for specific seismic arrivals. These kernels capture the volumetric sensitivity associated with the selected waveform and highlight prominent effects of topography on seismic-wave propagation in central Italy.
    Beschreibung: Published
    Beschreibung: JCR Journal
    Beschreibung: restricted
    Schlagwort(e): Wave Propagation ; Earthquake ; Ground Motion ; Basin & Site Effects ; Topographic Effects ; Numerical Modelling ; Spectral-Element Methods ; Adjoint Methods ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 6
    Publikationsdatum: 2017-04-04
    Beschreibung: On 20 May 2012, at 02:03:52 GMT, an earthquake with Mw 6.1 (RCMT, http://www.bo.ingv.it/RCMT) occurred in northern Italy striking a densely populated area. The mainshock was followed a few hours later by two severe aftershocks having the same local magnitude (Ml 5.1, 1 and 2 in Figure 1a), and by hundreds of smaller aftershocks. Nine days later, on 29 May, at 07:00:03 GMT, a second event with moment magnitude Mw 6.0 (RCMT, http://www.bo.ingv.it/RCMT) occurred to the west, on an adjacent fault segment. This event was also followed by hundreds of aftershocks, three of them having local magnitude 5.3, 5.2 and 5.1 (3, 4 and 5, respectively, in Figure 1a) (locations from Istituto Nazionale di Geofisica e Vulcanologia, hereinafter INGV, http://iside.rm.ingv.it/; Malagnini et al., 2012; Scognamiglio et al., 2012). Despite the moderate number of casualties if compared to other major events in the Italian history, the economic loss was extremely high, resulting in about EUR 5 billion (AON Benfield, 2012, http://www.aon.com/), as the majority of Italian industrial activities and infrastructures concentrate in this area, the eastern Po plain, which is the largest sedimentary basin in Italy. The mainshocks are associated to two thrust faults with an approximate E-W trend dipping to the South (Figure 1b). The majority of the faults in this region are located in the upper crust, at depths lower than 10 km. The two main shocks are among the strongest earthquakes generated by thrust faults ever recorded in Italy in the instrumental era. The Emilia sequence has been extensively recorded by several strong-motion networks, operating in the Italian territory and neighbouring countries. Some of the networks acquire continuous data streams at their national data centres, which are nodes of EIDA (European Integrated Data Archive, hhtp://eida.rm.ingv.it), a federation of several archives, so that the waveforms can be obtained immediately after the occurrence of an event. Other networks, such as the Italian accelerometric network (RAN), managed by the Italian Department of the Civil Protection (hereinafter DPC), distribute the acceleration waveforms through their web site (http://protezionecivile.gov.it). The data set explored in this study is relative to the six events of the sequence having Ml 〉 5 (Table 1) and consists in 365 accelerograms recorded within a distance of 200 km from the epicentres, that were provided by the permanent and temporary seismic networks of INGV, the Swiss Seismological Service (SED, http://www.seismo.ethz.ch/index) and the DPC.
    Beschreibung: Published
    Beschreibung: 629-644
    Beschreibung: 1.1. TTC - Monitoraggio sismico del territorio nazionale
    Beschreibung: JCR Journal
    Beschreibung: open
    Schlagwort(e): Strong motion ; May-June 2012 Emilia Romagna earthquake sequence ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous ; 04. Solid Earth::04.06. Seismology::04.06.04. Ground motion ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 7
    Publikationsdatum: 2017-04-03
    Beschreibung: The seismic sequence that occurred in the Abruzzo Apennines near L’Aquila (Italy) in April 2009 caused extensive damage and a large number of casual- ties (more than 300). The earthquake struck an area in the Italian Apennines chain where several faults, belonging to adjacent seismotectonic domains, create a complex tectonic regime resulting from the interaction among regional stress buildup, local stress changes caused by individual earthquakes, and viscous-elastic stress relaxation. Understanding such complex interaction in the Apennines can lead to a large step for- ward in the seismic risk mitigation in Italy. The Abruzzo earthquake has been very well recorded by interferometric synthetic aperture radar (InSAR) data, much better than the first Italian earthquake ever recorded by satellites, namely, the 1997 Umbria–Marche earthquake. ENVISAT (ENVIronmental SATellite) data for the Abruzzo earthquake are, in fact, very clear and allow an accurate reconstruction of the faulting mechanism. We present here an accurate inversion of vertical deformation data obtained by ENVISAT images, aimed to give a detailed reconstruction of the fault geometry and slip distribu- tion. The resulting fault models are then used to compute, by a suitable theoretical model based on the elastic dislocation theory, the stress changes induced on the neigh- boring faults. The correlation of the subsequent mainshocks and aftershocks of the Abruzzo sequence with the volumes undergoing increasing Coulomb stress clearly evidence the triggering effect of coseismic stress changes on further seismicity. More- over, this analysis put in evidence which seismotectonic domains have been more heav- ily charged by stress released by the Abruzzo mainshocks. The most important faults significantly charged by the Abruzzo sequence belong to the Sulmona and Avezzano tectonic domains. Taking into account the average regional stress buildup in the area, the positive Coulomb stress changes caused by this earthquake can be seen as antici- pating the next earthquakes in the neighboring domains of 15–20 yr.
    Beschreibung: Published
    Beschreibung: 2340-2354
    Beschreibung: JCR Journal
    Beschreibung: restricted
    Schlagwort(e): Aquila Earthquakes of April 2009 ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 8
    Publikationsdatum: 2017-04-04
    Beschreibung: Rapid evaluation of strong ground-shaking maps after moderate-to-large earthquakes is crucial to recognizing those areas where the largest damage and losses are expected. These maps play a fundamental role for emergency management. This is particularly important for areas having high seismic risk potential and covered by dense seismic networks. In near-real-time applications, ground-shaking maps are produced by integrating recorded data and estimates obtained by using ground-motion predictive equations, which assume point-source models. However, particularly for large earthquakes, improvements in the predictions of the peak ground motion can be obtained when fault extension and orientation are available. In fact, detailed source information allows one to use a more robust source-to-site distance metric compared with hypocentral distance. In this paper, a technique for estimating both fault extent (in terms of its surface projection) and dominant rupture direction is presented. This technique can be used in near-real-time ground-motion map calculation codes with the aim of improving ground-motion estimates with respect to a point-source model. The model parameters are estimated by maximizing a probability density function based on the residuals between observed and predicted peak-ground-motion quantities, the latter obtained by using predictive equations. The model space to be investigated is defined through a Bayesian approach, and it is explored by a grid-searching technique. The effectiveness of the proposed technique is demonstrated by offline numerical tests using data from three earthquakes occurring in different seismotectonic environments. The selected earthquakes are the 17 August 1999 Mw 7.5 Kocaeli (Turkey) earthquake, the 6 April 2009 Mw 6.3 L’Aquila (Italy) earthquake, and the 17 January 1994 Mw 6.7 Northridge (California) earthquake. The obtained results show that the proposed technique allows for fast and first order estimates of the fault extent and dominant rupture direction, which could be used to improve ground-shaking map calculations.
    Beschreibung: Published
    Beschreibung: 661-679
    Beschreibung: 4.1. Metodologie sismologiche per l'ingegneria sismica
    Beschreibung: JCR Journal
    Beschreibung: restricted
    Schlagwort(e): Source directivity ; ShakeMap ; L'Aquila earthquake ; Northridge earthquake ; Kocaeli earthquake ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 9
    Publikationsdatum: 2017-04-03
    Beschreibung: The 2009 Mw 6.3 L’Aquila earthquake produced an impressive number of rotational effects on vertically organized objects such as chimneys, pillars, capitals, and gravestones. We present a dataset of such effects that consists of 105 observations at 37 different sites and represents a compendium of earthquake-induced instances of rotational effects that is unprecedented in recent times. We find that the absolute majority of the reported effects were observed in the epicentral zone and that most of the observations are located where the Mercalli–Cancani–Sieberg intensity is between 7 and 8–9. The evident asymmetry in the distribution of the rotational effects resembles the southeastward directivity of the macroseismic effects and highlights a significant convergence between rotations and damage. Finally, we perform some qualitative analyses to recognize and evaluate which geological and seismological parameters can be significant contributors to local rotations. We find that surface geology and amplification of the seismic motion at each reported location strongly influence the occurrence and the nature of the earthquake-induced rotational effects. Conversely, the contribution of the pattern of slip distribution on the fault plane plays only a secondary role in enhancing the rotational motion at each site.
    Beschreibung: Published
    Beschreibung: 1109-1120
    Beschreibung: JCR Journal
    Beschreibung: restricted
    Schlagwort(e): L’Aquila earthquake ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 10
    Publikationsdatum: 2017-04-04
    Beschreibung: In widely used -2 source models the characteristics of high frequency radiation are described as being flat for frequencies between the source corner frequency and an upper limiting frequency fmax. Deviations from this behavior are described in a parameter which is understood as a general measure of the changes the signal undergoes on its way from the source to the receiver. In this study, we calculated  in Southeastern Sicily by using microearthquakes belonging to three different seismic sequences occurring in the area in 1990, 1999-2001, and 2002. The selected events form four different clusters whose seismic sources are located within a 2 km radius. Although the source-to-station paths are approximately the same inside a given cluster, the values of  change considerably at the same recording site from one event to another, also in the case of events having the same magnitude. We parameterized  in terms of event (E), and path (P and Diff) contributions. The term P represents the contribution on total  of both the whole source-to- station path and the near-surface geology, while Diff models the possible spatial variation in the parameter measured with respect to a reference source-station direction. Results show that the source contribution is not negligible and that there is a positive correlation with source size exists. Moreover, the hypothesis of a laterally homogeneous crustal structure within the area in question is not appropriate and significant variation in attenuating properties of the medium may occur in a very small distance range (also in the order of a few tens of meters). Our analysis suggests that the origin of the above mentioned variability is located near the recording site. Synthetic spectra are also computed in order to verify the actual significance of the parameterization employed and its capacity to separate the source and the path contribution to . We describe our spectra as a product of a Brune-type source spectrum and an exponential shaping term accounting for propagation effects. The seismic moments range between 3.8 ×1011 and 5.2 ×1013 N·m, the source radii range between 176 and 669 m, while the stress drop varies from 0.01 to 0.67 MPa.
    Beschreibung: Published
    Beschreibung: 1796-1809
    Beschreibung: 3.1. Fisica dei terremoti
    Beschreibung: JCR Journal
    Beschreibung: open
    Schlagwort(e): High-frequency spectral decay in P-wave acceleration ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 11
    Publikationsdatum: 2017-04-04
    Beschreibung: The recent Mw 6.3 destructive L’Aquila earthquake has further stimulated the improvement of the Italian operational earthquake forecasting capability at different time intervals. Here, we describe a medium-term (10-year) forecast model for Mw ≥5:5 earthquakes in Italy that aims at opening new possibilities for risk mitigation purposes. While a longer forecast yielded by the national seismic-hazard map is the primary component in establishing the building code, a medium-term earthquake forecast model may be useful to prioritize additional risk mitigation strategies such as the retrofitting of vulnerable structures. In particular, we have developed an earthquake occurrence model for a 10-year forecast that consists of a weighted average of time-independent and different types of available time-dependent models, based on seismotectonic zonations and regular grids. The inclusion of time-dependent models marks a difference with the earthquake occurrence model of the national seismic-hazard map, and it is motivated by the fact that, at the 10-year scale, the contribution of time-dependency in the earthquake occurrence process may play a major role. The models are assembled through a simple averaging scheme whereby each model is weighted through the results of a retrospective testing phase similar to the ones carried out in the framework of the Collaboratory for the Study of Earthquake Predictability. In this way, the most hazardous Italian areas in the next ten years will arise from a combination of distinct models that place more emphasis on different aspects of the earthquake occurrence process, such as earthquake clustering, historical seismic rate, and the presence of delayed faults capable of large events. Finally, we report new challenges and possible developments for future updating of the model.
    Beschreibung: Published
    Beschreibung: 1195-1213
    Beschreibung: 4.2. TTC - Modelli per la stima della pericolosità sismica a scala nazionale
    Beschreibung: JCR Journal
    Beschreibung: restricted
    Schlagwort(e): Earthquake occurrence ; time-dependent and independent earthquake occurrence models ; csep testing ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 12
    Publikationsdatum: 2017-04-04
    Beschreibung: In this paper, we adopt three ground-motion simulation techniques (EXSIM, Motazedian and Atkinson, 2005, DSM, Pacor et al., 2005 and HIC, Gallovič and Brokešová, 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. First, we simulate the recorded strong-motion data and validate the model parameters by computing spectral acceleration and peak amplitudes 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 ± one 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 inter-event variability.
    Beschreibung: In press
    Beschreibung: 4.1. Metodologie sismologiche per l'ingegneria sismica
    Beschreibung: JCR Journal
    Beschreibung: restricted
    Schlagwort(e): Irpinia 1980 earthquake ; ground-motion simulation ; ground-motion variability ; scenario events ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics ; 04. Solid Earth::04.06. Seismology::04.06.04. Ground motion
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 13
    Publikationsdatum: 2017-04-04
    Beschreibung: The MW 8.8 mega-thrust earthquake and tsunami that occurred on February 27, 2010, offshore Maule region, Chile, was not unexpected. A clearly identified seismic gap existed in an area where tectonic loading has been accumulating since the great 1835 earthquake experienced and described by Darwin during the voyage of the Beagle. Here we jointly invert tsunami and geodetic data (InSAR, GPS, land-level changes), to derive a robust model for the co-seismic slip distribution and induced co-seismic stress changes, and compare them to past earthquakes and the pre-seismic locking distribution. We aim to assess if the Maule earthquake has filled the Darwin gap, decreasing the probability of a future shock . We find that the main slip patch is located to the north of the gap, overlapping the rupture zone of the MW 8.0 1928 earthquake, and that a secondary concentration of slip occurred to the south; the Darwin gap was only partially filled and a zone of high pre-seismic locking remains unbroken. This observation is not consistent with the assumption that distributions of seismic rupture might be correlated with pre-seismic locking, potentially allowing the anticipation of slip distributions in seismic gaps. Moreover, increased stress on this unbroken patch might have increased the probability of another major to great earthquake there in the near future.
    Beschreibung: Published
    Beschreibung: 173-177
    Beschreibung: 3.1. Fisica dei terremoti
    Beschreibung: 4.2. TTC - Modelli per la stima della pericolosità sismica a scala nazionale
    Beschreibung: JCR Journal
    Beschreibung: restricted
    Schlagwort(e): Source process ; Chile ; Tsunami ; Joint Inversion ; Seismic Gap ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous ; 04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress ; 04. Solid Earth::04.07. Tectonophysics::04.07.06. Subduction related processes ; 05. General::05.01. Computational geophysics::05.01.03. Inverse methods
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 14
    Publikationsdatum: 2017-04-04
    Beschreibung: The analysis of the seismic attenuation is a prominent and problematic component of hazard assessment. Over the last decade it has become increasingly clear that the intrinsic uncertainty of the decay process must be expressed in probabilistic terms. This implies estimating the probability distribution of the intensity at a site Is as the combination of the distribution of the decay DI and of the distribution of the intensity I0 found for the area surrounding that site. We focus here on the estimation of the distribution of DI. Previous studies presented in the literature show that the intensity decay in Italian territory varies greatly from one region to another, and depends on many factors, some of them not easily measurable. Assuming that the decay shows a similar behavior in function of the epicenter-site distance when the same geophysical conditions and building vulnerability characterize different macroseismic fields, we have classified some macroseismic fields drawn from the Italian felt report database by applying a clustering algorithm. Earthquakes in the same class constitute the input of a two-step procedure for the Bayesian estimation of the probability distribution of I at any distance from the epicenter, conditioned on I0, where DI is considered an integer, random variable, following a binomial distribution. The scenario generated by a future earthquake is forecast either by the predictive distribution in each distance bin, or by a binomial distribution whose parameter is a continuous function of the distance. The estimated distributions have been applied to forecast the scenario actually produced by the Colfiorito earthquake on 1997/09/26; for both options the expected and observed intensities have been compared on the basis of some validation criteria. The same procedure has been repeated using the probability distribution of DI estimated on the basis of each class of macroseismic fields identified by the clustering algorithm.
    Beschreibung: Published
    Beschreibung: 2876-2892
    Beschreibung: 4.1. Metodologie sismologiche per l'ingegneria sismica
    Beschreibung: JCR Journal
    Beschreibung: open
    Schlagwort(e): Macroseismic fields ; Probability Distribution of the Intensity at Site ; Attenuation trends ; Colfiorito 1997 earthquake ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 15
    Publikationsdatum: 2017-04-04
    Beschreibung: This study investigates the engineering applicability of two conceptually different finite-fault simulation techniques. We focus our attention on two important aspects: first to quantify the capability of the methods to reproduce the observed ground-motion parameters (peaks and integral quantities); second to quantify the dependence of the strong-motion parameters on the variability in the large-scale kinematic definition of the source (i.e., position of the nucleation point, value of the rupture velocity, and distribution of the final slip on the fault). We applied an approximated simulation technique, the deterministic-stochastic method and a broadband technique, the hybrid-integral-composite method, to model the 1984 Mw 5.7 Gubbio, central Italy, earthquake, at five accelerometric stations. We first optimize the position of the nucleation point and the value of the rupture velocity for three different final slip distributions on the fault by minimizing an error function in terms of acceleration response spectra in the frequency band from 1 to 9 Hz. We found that the best model is given by a rupture propagating at about 2:65 km=sec from a hypocenter located approximately at the center of the fault. In the second part of the article we calculate more than 2400 scenarios varying the kinematic source parameters. At the five sites we compute the residuals distributions for the various strongmotion parameters and show that their standard deviations depend on the source parameterization adopted by the two techniques. Furthermore, we show that Arias Intensity (AI) and significant duration are characterized by the largest and smallest standard deviation, respectively. Housner Intensity is better modeled and less affected by uncertainties in the source kinematic parameters than AI. The fact that the uncertainties in the kinematic model affects the variability of different ground-motion parameters in different ways has to be taken into account when performing hazard assessment and earthquake engineering studies for future events.
    Beschreibung: Published
    Beschreibung: 647-663
    Beschreibung: 4.1. Metodologie sismologiche per l'ingegneria sismica
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): ground-motion simulation ; Gubbio 1984 ; ground-motion variability ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics ; 04. Solid Earth::04.06. Seismology::04.06.04. Ground motion
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 16
    Publikationsdatum: 2017-04-04
    Beschreibung: The Campi Flegrei caldera (southern Italy) is one of the most hazardous areas in the World as several hundred thousand people live there and where important socio-economic activities have developed. The caldera includes the western-most part of the city of Naples and extends into the Gulf of Pozzuoli (eastern Tyrrhenian basin; Fig. 1). The main feature of the present volcanic activity of the caldera is the episodic slow and high-amplitude soil movement (bradyseism) accompanied by intense and shallow seismic activity that only occurs during the uplift phase.
    Beschreibung: Published
    Beschreibung: 916-927
    Beschreibung: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Beschreibung: 1.8. Osservazioni di geofisica ambientale
    Beschreibung: JCR Journal
    Beschreibung: restricted
    Schlagwort(e): Campi Flegrei ; volcanic activity ; seafloor monitoring ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 17
    Publikationsdatum: 2017-04-04
    Beschreibung: The Mw6.3 2009 L’Aquila earthquake produced an impressive number of rotational effects on vertically organized objects such as chimneys, pillars, capitals and gravestones. We present the dataset of such effects, that consists of 105 observations at 37 different sites and represents a compendium of earthquake-induced istances of rotational effects that is unprecedented in recent times. We find that the absolute majority of the reported effects was observed in the epicentral zone and that most of the observations are located where the MCS intensity is between 7 and 8-9. The evident asymmetry in the distribution of the rotational effects resembles the southeastward directivity of the macroseismic effects and highlights a significant convergence between rotations and damage. Finally, we perform some qualitative analyses to recognize and evaluate which *Manuscript Click here to download Manuscript: revised_text.doc 2 geological and seismological parameters can be significant contributors to local rotations. We find that surface geology and amplification of the seismic motion at each reported location strongly influence the occurrence and the nature of the earthquake-induced rotational effects. Conversely, the contribution of the pattern of slip distribution on the fault plane plays only a secondary role in enhancing the rotational motion at each site.
    Beschreibung: In press
    Beschreibung: 1.11. TTC - Osservazioni e monitoraggio macrosismico del territorio nazionale
    Beschreibung: JCR Journal
    Beschreibung: open
    Schlagwort(e): l'aquila earthquake ; rotationale effects ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 18
    Publikationsdatum: 2017-04-04
    Beschreibung: This study investigates the engineering applicability of two conceptually different finite-fault simulation techniques. We focus our attention on two important aspects: first to quantify the capability of the methods to reproduce the observed ground-motion parameters (peaks and integral quantities); second to quantify the dependence of the strong-motion parameters on the variability in the large-scale kinematic definition of the source (i.e. position of nucleation point, value of the rupture velocity and distribution of the final slip on the fault). We applied an approximated simulation technique, the Deterministic-Stochastic Method DSM, and a broadband technique, the Hybrid-Integral-Composite method HIC, to model the 1984 Mw 5.7 Gubbio, central Italy, earthquake, at 5 accelerometric stations. We first optimize the position of nucleation point and the value of rupture velocity for three different final slip distributions on the fault by minimizing an error function in terms of acceleration response spectra in the frequency band from 1 to 9 Hz. We found that the best model is given by a rupture propagating at about 2.65 km/s from a hypocenter located approximately at the center of the fault. In the second part of the paper we calculate more than 2400 scenarios varying the kinematic source parameters. At the five sites we compute the residuals distributions for the various strong-motion parameters and show that their standard deviations depend on the source-parameterization adopted by the two techniques. Furthermore, we show that, Arias Intensity and significant duration are characterized by the largest and smallest standard deviation, respectively. Housner Intensity results better modeled and less affected by uncertainties in the source kinematic parameters than Arias Intensity. The fact that the uncertainties in the kinematic model affects the variability of different ground-motion parameters in different ways has to be taken into account when performing hazard assessment and earthquake engineering studies for future events.
    Beschreibung: In press
    Beschreibung: 4.1. Metodologie sismologiche per l'ingegneria sismica
    Beschreibung: JCR Journal
    Beschreibung: open
    Schlagwort(e): ground-motion simulation ; Gubbio 1984 ; ground-motion variability ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics ; 04. Solid Earth::04.06. Seismology::04.06.04. Ground motion
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 19
    Publikationsdatum: 2019-03-05
    Beschreibung: New duration-based local (ML) and moment (Mw) magnitude scales are obtained for the Campi Flegrei area through analysis of a dataset of local volcanotectonic earthquakes. First, the S-wave quality factor for the investigated area was experimentally calculated, and then the distance-correction curve, log A0(r), to be used in the Richter formula ML = log Amax − log A0(r), was numerically estimated by measuring the attenuation properties and, hence, propagating a synthetic S-wave packet in the earth medium. The local magnitude scale was normalized to fit the Richter formula that was valid for Southern California at a distance of 10 km. ML was estimated by synthesizing Wood–Anderson seismograms and measuring the maximum amplitude. For the same dataset, the moment magnitude was obtained from S-wave distance-corrected and site-corrected displacement spectra. Comparisons between local and moment magnitudes determined, along with the old duration magnitude (MD) routinely used at the Istituto Nazionale di Geofisica e Vulcanologia– Osservatorio Vesuviano, are presented and discussed. Moreover, the relationships between ML and Mw calculated for two reference sites are also derived.
    Beschreibung: Published
    Beschreibung: 1964-1974
    Beschreibung: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Beschreibung: JCR Journal
    Beschreibung: open
    Schlagwort(e): magnitude ; Campi Flegrei ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 20
    Publikationsdatum: 2017-04-04
    Beschreibung: The spatial distribution of 414 earthquakes (1.0 ≤ ML ≤ 4.6), recorded from 1994 to 2002 in Southeastern Sicily (Italy), has been analyzed; it generally coincides with mapped Plio-Quaternary faults, including the NNW-SSE offshore fault system which is the most important tectonic structure of the area. For the best located events, we computed 70 focal mechanisms by combining P-wave polarities with S-wave polarizations. A predominance of strike-slip and normal faults was observed. Focal mechanisms were then inverted for stress tensor parameters using the algorithm of Gephart and Forsyth. The results highlighted a region governed mainly by a compressional stress regime. Moreover, anisotropy analysis of shear-waves showed a polarization of fast S-waves prevalently aligned in the NNW-SSE to NW-SE direction over the whole area. A finer analysis of stress tensor evidenced three regions characterized by slightly differing orientation of the greatest principal stress axis, 1. The eastern sector displays a nearly horizontal 1 trending NW-SE; the central sector is affected by a low dip NNW-SSE 1; whereas in the western sector a 1 NNW-SSE oriented, with a higher dip angle, was detected. Finally, the comparison of the spatial distribution of seismicity occurring during 1994-2002, with locations of previous instrumental earthquakes and larger (M ≥ 5.0) historical events showed that the seismic patterns are persistent.
    Beschreibung: Published
    Beschreibung: 1359–1374
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): Stress direction ; focal mechanisms ; Shear-Wave Anisotropy ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 21
    Publikationsdatum: 2017-04-04
    Beschreibung: In November 1999 and in January 2000, two microearthquake swarms occurred in Southeastern Sicily (Italy). They were analytically located in the depth range 17-25 km, some kilometers northward from the buried front of a regional foredeep, below the active thrust zone of the Sicily mountain chain. Their hypocentral distribution showed two distinct clusters, and comparison of the waveforms revealed clearly that the two swarms formed two distinct families of multiplet events. This led us: i) to carry out a precise relocation relative to two chosen master events of the families, and ii) to better define the geometrical structure of the two clusters. The cross-spectral method was applied to obtain precise readings of the wave onsets. SH-wave onsets were used instead of P-waves, as they showed clearer onsets and a good signal-to-noise ratio. Residuals of the relative locations showed small values, no more than several meters on average. The vertical extent of the two relocated clusters was 500 m and 250 m, respectively, while the horizontal extent was 250 m. Hypocenters of the first cluster clearly delineate a NNW trending plane with almost vertical dip, matching one nodal plane of the focal mechanism obtained as a composite solution of all events of the cluster. Given the considerable gap angles, because of unfavorable network geometry with respect to the events, the stability of our results was tested carrying out a Montecarlo experiment. Varying the onset times randomly in the range of 5 ms, a dispersion of the locations less than 10 m in longitude, and less than 50 m both in latitude and depth was found. Similar results were obtained when comparing relocations carried out with different master events. Thus, the overall geometrical characteristics of the clusters were not affected seriously by random errors. Considering the geo-structural framework of the region, together with the location and time evolution of the two clusters, fluids of plutonic origin are suggested as the trigger mechanism.
    Beschreibung: Published
    Beschreibung: 1479–1497
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): earthquake swarms ; cross-correlation ; relative location ; master-event technique ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 22
    Publikationsdatum: 2017-04-04
    Beschreibung: A long sequence of moderate-magnitude earthquakes (5 M 6) struck central Italy in September and October 1997. At the end of the sequence a year later, the seismogenic area extends for about 60 km along the Apennines. The analysis of historical seismicity suggests that this seismic sequence filled a 700-year gap in this portion of the chain. Other historical sequences in the same area are characterized by prolonged seismic release on adjacent fault segments, probably due to the involvement of shallow and complex structures inherited by the compressive tectonics. The distribution of seismicity and the fault-plane solutions show that the extension in this region is accomplished by normal faults dipping at relatively low angles ( 40 ) to the southwest. The focal mechanisms of the largest shocks reveal normal faulting with extension perpendicular to the Apenninic chain (northeast–southwest), consistently with the Quaternary tectonics of the internal sector of the northern Apennine belt and with previous earthquakes in adjacent regions. Three mainshocks occurred on distinct 5- to 10-km-long fault segments, adjacent and slightly offset between each other. High-quality aftershock locations show that seismicity is confined within the sedimentary Mesozoic cover in the upper 8 km of the crust and that most of the aftershocks are shallower than the largest shocks, which nucleated at 6-km depth. Faults evidenced by aftershock locations have a planar geometry and show increased complexity toward the surface. Most of the aftershock focal mechanisms are dominated by normal faulting. Several strike-slip events occurred at shallow depths, reactivating portions of pre-existing thrust planes that segment the normal fault system. The spatiotemporal evolution of seismicity shows a peculiar migration of hypocenters along the strike of the main faults with multiple ruptures and the activation of fault segments before the occurrence of the main rupture episodes.
    Beschreibung: Published
    Beschreibung: 99-116
    Beschreibung: reserved
    Schlagwort(e): Seismic ; Sequence ; Central Italy ; Apennines ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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    Format: application/pdf
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