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Falcone, Giuseppe
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Falcone, Giuseppe
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giuseppe.falcone@ingv.it
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staff
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Scopus Author ID
16312404300
Researcher ID
G-6689-2011
41 results
Now showing 1 - 10 of 41
- PublicationRestrictedWhen time and faults matter: towards a time-dependent probabilistic SHA in Calabria, Italy(2017)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; In this study, we attempt to improve the standards in Probabilistic Seismic Hazard Assessment (PSHA) towards a time-dependent hazard assessment by using the most advanced methods and new databases for the Calabria region, Italy. In this perspective we improve the knowledge of the seismotectonic framework of the Calabrian region using geologic, tectonic, paleoseismological, and macroseismic information available in the literature. We built up a PSHA model based on the long-term recurrence behavior of seismogenic faults, together with the spatial distribution of historical earthquakes. We derive the characteristic earthquake model for those sources capable of rupturing the entire fault segment (full-rupture) independently with a single event of maximum magnitude. We apply the floating rupture model to those earthquakes whose location is not known sufficiently constrained. We thus associate these events with longer fault systems, assuming that any such earthquake can rupture anywhere within the particular fault system (floating partial-rupture) with uniform probability. We use a Brownian Passage Time (BPT) model characterized by mean recurrence, aperiodicity, or uncertainty in the recurrence distribution and elapsed time since the last characteristic earthquake. The purpose of this BPT model is to express the time-dependence of the seismic processes to predict the future ground motions in the region. Besides, we consider the influence on the probability of earthquake occurrence controlled by the change in static Coulomb stress (ΔCFF) due to fault interaction; to pursue this, we adopt a model built on the fusion of BPT model (BPT + ΔCFF). We present our results for both time-dependent (renewal) and time-independent (Poisson) models in terms of Peak Ground Acceleration (PGA) maps for 10% probability of exceedance in 50 years. The hazard may increase by more than 20% or decrease by as much as 50% depending on the different occurrence model. Seismic hazard in terms of PGA decreases about 20% in the Messina Strait, where a recent major earthquake took place, with respect to traditional time-independent estimates. PGA near the city of Cosenza reaches ~ 0.36 g for the time-independent model and 0.40 g for the case of the time-dependent one (i.e. a 15% increase). Both the time-dependent and time-independent models for the period of 2015–2065 demonstrate that the city of Cosenza and surrounding areas bear the highest seismic hazard in Calabria.1588 18 - PublicationOpen AccessComprehensive and Topical Evaluations of Earthquake Forecasts in Terms of Number, Time, Space, and Magnitude(2013-06)
; ; ; ; ; ; ; ; ; Among scoring methods employed to determine the performance of probability predictions, the log-likelihood method is the most common and useful. Although the log-likelihood score evaluates the comprehensive power of forecasts, we need to further evaluate the topical predictive powers of respective factors of seismicity, such as total numbers, occurrence times, locations, and magnitudes. For this purpose, we used the conditional- or marginal-likelihood function based on the observed events. Such topical scores reveal both strengths and weaknesses of a forecasting model and suggest the necessary improvements. We applied these scores to the probability forecasts during the devastating period of March 2011, during which the Mw 9.0 Off the Pacific Coast of Tohoku-Oki earthquake struck. However, the evaluations did not suggest that any of the prospective forecast models were consistently satisfactory. Hence, we undertook two additional types of retrospective forecasting experiments to investigate the reasons, including the possibility that the seismicity rate pattern has changed after the M 9 mega-earthquake. In addition, our experiments revealed a technical difficulty in the one-day forecasting protocol adopted by the Collaboratory for the Study of Earthquake Predictability (CSEP). Results of further experiments lead us to recommend specific modifications to the CSEP protocols, leading to real-time forecasts and their evaluations159 96 - PublicationRestrictedEarthquake forecasting during the complex Amatrice-Norcia seismic sequence(2017-09)
; ; ; ; ; Earthquake forecasting is the ultimate challenge for seismologists, because it condenses the scientific knowledge about the earthquake occurrence process, and it is an essential component of any sound risk mitigation planning. It is commonly assumed that, in the short term, trustworthy earthquake forecasts are possible only for typical aftershock sequences, where the largest shock is followed by many smaller earthquakes that decay with time according to the Omori power law. We show that the current Italian operational earthquake forecasting system issued statistically reliable and skillful space-time-magnitude forecasts of the largest earthquakes during the complex 2016-2017 Amatrice-Norcia sequence, which is characterized by several bursts of seismicity and a significant deviation from the Omori law. This capability to deliver statistically reliable forecasts is an essential component of any program to assist public decision-makers and citizens in the challenging risk management of complex seismic sequences.210 5 - PublicationRestrictedStress interaction effect on the occurrence probability of characteristic earthquakes in Central Apennines(2008-08-19)
; ; ; ; ;Console, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Murru, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Falcone, G.; Earth Science Department, Messina University ;Catalli, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; ; ; 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.155 26 - PublicationOpen AccessWhat is the impact of the August 24, 2016 Amatrice earthquake on the seismic hazard assessment in central Italy?(2016)
; ; ; ; ; ; ; The recent Amatrice strong event (Mw6.0) occurred on August 24, 2016 in Central Apennines (Italy) in a seismic gap zone, motivated us to study and provide better understanding of the seismic hazard assessment in the macro area defined as “Central Italy”. The area affected by the sequence is placed between the Mw6.0 1997 Colfiorito sequence to the north (Umbria-Marche region) the Campotosto area hit by the 2009 L’Aquila sequence Mw6.3 (Abruzzo region) to the south. The Amatrice earthquake occurred while there was an ongoing effort to update the 2004 seismic hazard map (MPS04) for the Italian territory, requested in 2015 by the Italian Civil Protection Agency to the Center for Seismic Hazard (CPS) of the Istituto Nazionale di Geofisica e Vulcanologia INGV. Therefore, in this study we brought to our attention new earthquake source data and recently developed ground-motion prediction equations (GMPEs). Our aim was to validate whether the seismic hazard assessment in this area has changed with respect to 2004, year in which the MPS04 map was released. In order to understand the impact of the recent earthquakes on the seismic hazard assessment in central Italy we compared the annual seismic rates calculated using a smoothed seismicity approach over two different periods; the Parametric Catalog of the Historical Italian earthquakes (CPTI15) from 1871 to 2003 and the historical and instrumental catalogs from 1871 up to 31 August 2016. Results are presented also in terms of peak ground acceleration (PGA), using the recent ground-motion prediction equations (GMPEs) at Amatrice, interested by the 2016 sequence.814 96 - PublicationOpen AccessApplication of an ensemble earthquake rate model in Italy, considering seismic catalogs and fault moment release(2020)
; ; ; ; ; ; ; We develop an ensemble earthquake rate model that provides spatially variable time-independent (Poisson) long-term annual occurrence rates of seismic events throughout Italy, for magnitude bin of 0.1 units from Mw ≥4.5 in spatial cells of 0.1° x 0.1°. We weighed seismic activity rates of smoothed seismicity and fault-based inputs to build our earthquake rupture forecast model, merging it into a single ensemble model. Both inputs adopt a tapered Gutenberg-Richter relation with a single b-value and a single corner magnitude estimated by earthquakes catalog. The spatial smoothed seismicity was obtained using the classical kernel smoothing method with the inclusion of magnitude dependent completeness periods applied to the Historical (CPTI15) and Instrumental seismic catalogs. For each seismogenic source provided by the Database of the Individual Seismogenic Sources (DISS), we computed the annual rate of the events above Mw4.5, assuming that the seismic moments of the earthquakes generated by each fault are distributed according to the tapered Gutenberg-Richter relation with the same parameters of the smoothed seismicity models. Comparing seismic annual rates of the catalogs with those of the seismogenic sources, we realized that there is a good agreement between these rates in Central Apennines zones, whereas the seismogenic rates are higher than those of the catalogs in the north east and south of Italy. We also tested our model against the strong Italian earthquakes (Mw5.5+), in order to check if the total number (N-test) and the spatial distribution (S-test) of these events was compatible with our model, obtaining good results, i.e. high p-values in the test. The final model will be a branch of the new Italian seismic hazard map.259 112 - PublicationOpen AccessRetrospective forecasting of M≥4.0 earthquakes in New Zealand(2010)
; ; ; ;Console, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Murru, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Falcone, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; ; 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.166 324 - PublicationOpen AccessTemporal Variations of Seismicity Rates and Gutenberg–Richterb-Values for a Stochastic Declustered Catalog: An Example in Central Italy(2023)
; ; ; ; ; ; ; ;; ; ; ; ; One important aspect of the seismicity is the spatiotemporal clustering; hence, the distinction between independent and triggered events is a critical part of the analysis of seismic catalogs. Stochastic declustering of seismicity allows a probabilistic distinction between these two kinds of events. Such an approach, usually performed with the epidemic‐type aftershock sequence (ETAS) model, avoids the bias in the estimation of the frequency–magnitude distribution parameters if we consider a subset of the catalog, that is, only the independent or the triggered events. In this article, we present a framework to properly include the probabilities of any event to be independent (or triggered) both in the temporal variation of the seismic rates and in the estimation of the b‐value of the Gutenberg–Richter law. This framework is then applied to a high‐definition seismic catalog in the central part of Italy covering the period from April 2010 to December 2015. The results of our analysis show that the seismic activity from the beginning of the catalog to March 2013 is characterized by a low degree of clustering and a relatively high b‐value, whereas the following period exhibits a higher degree of clustering and a smaller b‐value.52 73 - PublicationOpen AccessAn extensive study of clustering features of seismicity in Italy from 2005 to 2016(2019-01)
; ; ; ; ; ; ; To study the characteristics of seismicity in Italy, we have made use of the ISIDE (Italian Seismic Instrumental and parametric Data-basE) catalogue since 2005 April 16, which was compiled by the Istituto Nazionale di Geofisica e Vulcanologia (INGV). This catalogue includes high quality records of the occurrence times, locations, magnitude and other information about the earthquakes that occurred in and near Italy. We made use of the original form and two extended versions of the space–time ETAS model, namely, the 2-D ETAS model, the hypocentral 3-D ETAS model and the finite-source (FS) ETAS model. Our results show that the rupture geometries of large earthquakes, including the L’Aquila (2009 April 6 Mw6.1/ML5.9 ), the Finale-Emilia (2012 May 20, Mw5.8/ML5.9), the Amatrice (2016 August 24 Mw6.0/ML6.0) and the Norcia (2016 October 30 Mw6.5/ML6.1) earthquakes, control the spatial locations of their direct aftershocks. These direct aftershocks are mainly distributed in some areas adjacent to, but seldom at, the parts with the biggest slips along the main shock rupture, implying that aftershocks compensate the rupture of the main shock. The background seismicity rate is not stationary in all these areas, but shows several phases tuned by the major events. Regarding the difference among the three versions of the ETAS model, we found: (i) hypocentral depth plays an important role in triggering; (ii) when classifying background and triggered seismicity, all three models give similar results, but when classifying the family trees in the catalogue, the geometry of an earthquake rupture should be considered. The FS ETAS model classifies most aftershock events as aftershocks of the main shock; (iii) adopting point sources together with isotropic spatial response causes underestimates of the effects triggered by the main shocks. Such biases can be corrected by incorporating the rupture geometries of major events into the model formulation. Compared to the original point-source model, more direct aftershocks from the main shock are estimated by using the FS ETAS model and (iv) The rupture geometry of a major earthquake can be inverted to some extent from small aftershocks following it by fitting to the finite-source ETAS model.233 75 - PublicationOpen AccessOperational Earthquake Forecasting in Italy: validation after 10 yr of operativity(2023)
; ; ; ; ; ; ; In this paper, we gather and take stock of the results produced by the Operational Earthquake Forecasting (OEF) system in Italy, during its first 10 yr of operativity. The system is run in real-time: every midnight and after each ML 3.5 + event, it produces the weekly forecast of earthquakes expected by an ensemble model in each cell of a spatial grid covering the entire Italian territory. To e v aluate the performance skill of the OEF-Italy forecasts, we consider here standard tests of the Collaboratory for the Study of Earthquake Predictability, which have been opportunely adapted to the case of the overlapped weekly OEF forecasts; then we also adopt new performance measures borrowed from other research fields, like meteorology, specific to validate alarm-based systems by a binary criterion (forecast: yes/no; occurrence: yes/no). Our final aim is to: (i) investigate possible weaknesses and room for improvements in the OEF-Italy stochastic modelling, (ii) provide performance measures that could be helpful for stakeholders who act through a boolean logic (making an action or not) and (iii) highlight possible features in the Italian tectonic seismic activity.63 104