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  • 1
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    Stress interaction effect on the occurrence probability of characteristic earthquakes in Central Apennines (2008)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: In this study, we compute the effect of stress change due to previous historical earthquakes on the probability of occurrence of future earthquakes on neighboring faults. Following a methodology developed in the last decade, we start from the estimate of the probability of occurrence in the next 50 years for a characteristic earthquake on known seismogenic structures, based on a time-dependent renewal model. Then a physical model for the Coulomb stress change caused by previous earthquakes on these structures is applied. The influence of this stress change on the occurrence rate of characteristic earthquakes is computed, taking into account both permanent (clock advance) and temporary (rate-and-state) perturbations. We apply this method to the computation of earthquake hazard of the main seismogenic structures recognized in the Central and Southern Apennines region, for which both historical and paleoseismological data are available. This study provides the opportunity of reviewing the problems connected with the estimate of the parameters of a renewal model in case of characteristic earthquakes characterized by return times longer than the time spanned by the available catalogues and the applicability of the concept of characteristic earthquake itself. The results show that the estimated effect of earthquake interaction in this region is small compared with the uncertainties affecting the statistical model used for the basic time-dependent hazard assessment.
    Description: Published
    Description: B08313
    Description: 3.1. Fisica dei terremoti
    Description: 3.2. Tettonica attiva
    Description: 4.2. TTC - Scenari e mappe di pericolosità sismica
    Description: JCR Journal
    Description: reserved
    Keywords: Stress interaction, occurrence probability, characteristic earthquakes ; 01. Atmosphere::01.02. Ionosphere::01.02.03. Forecasts ; 04. Solid Earth::04.04. Geology::04.04.01. Earthquake geology and paleoseismology ; 04. Solid Earth::04.04. Geology::04.04.06. Rheology, friction, and structure of fault zones ; 04. Solid Earth::04.06. Seismology::04.06.02. Earthquake interactions and probability ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
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    Le Sorgenti sismiche: teoria ed osservazioni (2008)
    Details
    Publication Date: 2017-04-04
    Description: Scopo di questo lavoro è quello di fornire al lettore (più o meno esperto) uno strumento per la comprensione (concettuale ed analitica) di alcuni aspetti della teoria dinamica dell’elasticità, passando poi alla rappresentazione delle sorgenti sismiche, alla loro radiazione ed alla determinazione del loro meccanismo. Il terremoto infatti, non è altro che l’effetto delle onde sismiche, cioè il processo di oscillazione della Terra e, in particolare, della superficie terrestre, dove tale oscillazione è osservabile. La sorgente del terremoto (o sorgente sismica) è la sorgente delle onde sismiche. Nel capitolo 1 si fa riferimento in particolare al più semplice problema dinamico per un mezzo isotropo; la sorgente sismica infatti è forza impulsiva applicata ad un solo punto e orientata come uno degli assi del sistema di riferimento. E’ stata descritta la relazione che rappresenta la radiazione emessa da tali sorgenti in un mezzo elastico illimitato, omogeneo ed isotropo fino ad arrivare alla soluzione rappresentata dal Tensore di Green. Successivamente, (capitolo 2), viene fornita una descrizione sulla rappresentazione delle sorgenti sismiche sia in modo analitico che concettuale. Anche in questo caso è fatta una trattazione completa del problema, per poi giungere alla definizione di tensore momento sismico. Il terzo capitolo riguarda invece la trattazione sulla radiazione della sorgente sismica, sul campo degli spostamenti e sulle funzioni di irraggiamento, partendo dai risultati del primo e del secondo capitolo. Infine nella quarta ed ultima parte si è descritto il meccanismo focale di frattura, funzioni di irraggiamento per una frattura (orientata secondo gli assi o arbitrariamente) descrivendo la sfera focale e le sue proiezioni ed alcuni metodi per la determinazione del meccanismo focale.
    Description: Istituto Nazionale di Geofisica e Vulcanologia
    Description: Published
    Description: 3.1. Fisica dei terremoti
    Description: 5.6. Consulenze in favore di istituzioni nazionali e attività nell'ambito di trattati internazionali
    Description: open
    Keywords: sorgenti sismiche ; elastodinamica ; meccanismi focali di frattura ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: report
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  • 3
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    Earthquake occurrence models in the short and long term for the Italian seismicity (2010)
    Details
    Publication Date: 2017-04-04
    Description: The ETES, ERS and LTST models have been submitted to the CSEP (Collaboratory for the study of Earthquake Predictability) forecast testing for Italy (ETH-Zurich) and locked down to test their validity on real data in a forward way starting from August 1, 2009.
    Description: This work describes three earthquake occurrence models, two in the short-(24 hour) and one in long-term (5- and 10 year), applied to the whole Italian territory in order to assess the occurrence probability of future (M≥5.0) earthquakes. The first model for short-term forecasts is a purely stochastic Epidemic Type Earthquake Sequence model (ETES). The second short-term epidemic forecast is based on a model physically constrained by the application of Dieterich rate-state constitutive law to the earthquake clustering (ERS). The third forecast is based on a Long Term model that considers the perturbation of earthquake probability for interacting faults by static Coulomb stress changes (LTST). These models have been submitted to the CSEP (Collaboratory for the study of Earthquake Predictability) forecast testing for Italy (ETH-Zurich) and locked down to test their validity on real data in a forward way starting from August 1, 2009.
    Description: CSEP testing center for Italy
    Description: Submitted
    Description: 1-23
    Description: 3.1. Fisica dei terremoti
    Description: JCR Journal
    Description: open
    Keywords: CSEP forecast ; purely stochastic Epidemic Type Earthquake Sequence model (ETES) ; Long Term model (LTST) ; Earthquake rate and state model (ERS) ; 01. Atmosphere::01.02. Ionosphere::01.02.03. Forecasts
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: manuscript
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  • 4
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    Real time forecasts through an earthquake clustering model constrained by the rate-and-state constitutive law compared with a purely stochastic ETAS model (2008)
    Seismological society of America
    Details
    Publication Date: 2017-04-04
    Description: We propose an earthquake clustering model based on the popular concept of epidemic models. In these models every earthquake can be regarded as both triggered by previous events and as a potential triggering event for subsequent earthquakes (Ogata 1988, 1998; Ogata and Zhuang 2006 and reference therein; Console and Murru 2001; Console et al. 2003; Console et al. 2006a, 2006b; Helmstetter and Sornette 2002a, 2002b, 2003 for reviews; and Vere-Jones 2006 for review on the use of stochastic models for earthquake occurrence). The occurrence- rate density at any time and geographical location is computed by the contribution of every previous event using a kernel function that takes into proper account: (a) the magnitude of the triggering earthquake, (b) the spatial distance from the triggering event, and (c) the time interval between the triggering event and the instant considered for the computation. The magnitude distribution adopted here is the Gutenberg-Richter law (Gutenberg and Richter 1944). The above-mentioned criteria are implemented through the introduction of the rate-and-state constitutive law in a previously existing epidemic algorithm. The validity of the model can be tested in an exercise of realtime forecast.
    Description: Published
    Description: 49-56
    Description: 3.1. Fisica dei terremoti
    Description: JCR Journal
    Description: reserved
    Keywords: rate and state ; ETAS ; 01. Atmosphere::01.02. Ionosphere::01.02.03. Forecasts
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 5
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    Retrospective forecasting of M≥4.0 earthquakes in New Zealand (2010)
    springer
    Details
    Publication Date: 2019-10-11
    Description: We have applied a variation of the ETAS model, which is a stochastic triggering epidemic model incorporating short-term clustering, to data collected by the New Zealand Seismological Observatory-Wellington (Geonet) for forecasting earthquakes of moderate and large magnitude in the New Zealand region.
    Description: We have applied a variation of the ETAS model, which is a stochastic triggering epidemic model incorporating short-term clustering, to data collected by the New Zealand Seismological Observatory-Wellington (Geonet) for forecasting earthquakes of moderate and large magnitude in the New Zealand region. The model uses earthquake data only, with no explicit use of tectonic, geologic, or geodetic information. In this epidemic-type model every earthquake is regarded, at the same time, as being triggered by previous events and triggering following earthquakes. A maximum likelihood estimate of the model parameters has been performed on the learning period from 1960 to 2005 for earthquakes of magnitude 4.0 and larger. Forecast verification procedures have been carried out in forward-retrospective way on the January 2006-April 2008 data set, making use of statistical tools as the log-likelihood ratio, the Relative Operating Characteristics (ROC) diagrams, the Molchan error diagrams, the probability gain and the R-score. These procedures show that the clustering epidemic model achieves a log-likelihood ratio per event of the order of some units, and a probability gain up to several hundred times larger than a time-independent spatially uniform random forecasting hypothesis. The results show also that a significant component of the probability gain is linked to the time-independent spatial distribution of the seismicity used in the model.
    Description: Published
    Description: 693–707
    Description: 3T. Sorgente sismica
    Description: 6T. Studi di pericolosità sismica e da maremoto
    Description: JCR Journal
    Description: open
    Keywords: earthquake forecasting, real time forecasting ; epidemic model ; hypothesis testing ; error diagrams ; 01. Atmosphere::01.02. Ionosphere::01.02.03. Forecasts
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 6
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    Long-term seismogenesis in Greece: Comparison of the evolving stress field and precursory scale increase approaches (2007)
    Agu
    Details
    Publication Date: 2024-05-09
    Description: Recent strong (M 6.6) earthquakes in Greece are examined from the point of view of two current, but disparate, approaches to long-term seismogenesis. These are the evolving stress field (ESF) approach, in which earthquakes are considered to be triggered by accumulated stress changes from past earthquakes and tectonic loading on the major faults, and the precursory scale increase (Y) approach, in which a major earthquake is preceded in the long term by an increase in minor earthquake occurrences, with the magnitude of the precursory earthquakes, and the precursor time and area all scaling with the major earthquake magnitude. The strong earthquakes are found to be consistent with both approaches, and it is inferred that both approaches have a relevant role to play in the description of the long-term generation process of major earthquakes. A three-stage faulting model proposed previously to explain the Y phenomenon involves a major crack, which eventually fractures in the major earthquake, being formed before the onset of precursory seismicity. Hence we examine whether ESF can account for the formation of the major crack by examining the accumulated stress changes at the time of the onset of Y for each strong earthquake. In each case, the answer is in the affirmative; there is enhanced stress in the vicinity of the main shock at the time of the onset. The same is true for most, but not all, of the locations of precursory earthquakes.
    Description: Published
    Description: B05318
    Description: reserved
    Keywords: seismogenesis ; Greece: ; 04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution ; 04. Solid Earth::04.06. Seismology::04.06.02. Earthquake interactions and probability ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 7
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    Correlation of Static Stress Changes and Earthquake Occurrence in the North Aegean Region (2010)
    springer
    Details
    Publication Date: 2024-05-09
    Description: A systematic analysis is made of static Coulomb stress changes and earthquake occurrence in the area of the North Aegean Sea, Greece, in order to assess the prospect of using static stress changes to construct a regional earthquake likelihood model.
    Description: A systematic analysis is made of static Coulomb stress changes and earthquake occurrence in the area of the North Aegean Sea, Greece, in order to assess the prospect of using static stress changes to construct a regional earthquake likelihood model. The earthquake data set comprises all events of magnitude M ≥ 5.2 which have occurred since 1964. This is compared to the evolving stress field due to constant tectonic loading and perturbations due to coseismic slip associated with major earthquakes (M ≥ 6.4) over the same period. The stress was resolved for sixteen fault orientation classes, covering the observed focal mechanisms of all earthquakes in the region. Analysis using error diagrams shows that earthquake occurrence is better correlated with the constant tectonic loading component of the stress field than with the total stress field changes since 1964, and that little, if any, information on earthquake occurrence is lost if only the maximum of the tectonic loading over the fault orientation classes is considered. Moreover, the information on earthquake occurrence is actually increased by taking the maximum of the evolving stress field since 1964, and of its coseismic–slip component, over the fault orientation classes. The maximum, over fault orientation classes, of linear combinations of the tectonic loading and the evolving stress field is insignificantly better correlated with earthquake occurrence than the maximum of the tectonic loading by itself. A composite stress–change variable is constructed from ordering of the maximum tectonic loading component and the maximum coseismic–slip component, in order to optimize the correlation with earthquake occurrence. The results indicate that it would be difficult to construct a time–varying earthquake likelihood model from the evolving stress field that is more informative than a time–invariant model based on the constant tectonic loading.
    Description: This research was supported by the Foundation for Research, Science and Technology under contract CO5X0402. Geophysics Department, AUTH, contribution number 741.
    Description: Published
    Description: 1049–1066
    Description: 6T. Studi di pericolosità sismica e da maremoto
    Description: JCR Journal
    Description: open
    Keywords: Earthquake prediction ; static stress changes ; Greece ; 01. Atmosphere::01.02. Ionosphere::01.02.03. Forecasts
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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