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  • 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk  (23)
  • 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring  (16)
  • 04.06. Seismology  (14)
  • 04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution  (8)
  • Inversion
  • Seismological Society of America  (54)
  • 3
  • Wiley
Collection
Keywords
Publisher
Years
  • 1
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    The micro‐seismicity of Co. Donegal (Ireland): Defining baseline seismicity in a region of slow lithospheric deformation (2024)
    Wiley
    Details
    Publication Date: 2024-02-07
    Description: A catalogue of precisely located micro-seismicity is fundamental for investigating seismicity and rock physical properties in active tectonic and volcanic regions and for the definition of a ‘baseline’ seismicity, required for a safe future exploitation of georesource areas. In this study, we produce the first manually revised catalogue of micro-seismicity for Co. Donegal region (Ireland), an area of about 50K M2 of on-going deformation, aimed at localizing natural micro-seismic events occurred between 2012 and 2015. We develop a stochastic method based on a Markov chain Monte Carlo (McMC) sampling approach to compute earthquake hypocentral location parameters. Our results indicates that micro-seismicity is present with magnitudes lower than 2 (the highest magnitude is 2.8).The recorded seismicity is almost clustered along previously mapped NE-SW trending, steeply dipping faults and confined within the upper crust (focal depth less than 10 km). We also recorded anthropogenic seismicity mostly related to quarries' activity in the study area.
    Description: Published
    Description: 62-76
    Description: OST1 Alla ricerca dei Motori Geodinamici
    Description: JCR Journal
    Keywords: 04.06. Seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 2
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    The Influence of Cumulative Intensity on Macroseismic Source Parameters: The Case of 2016–2017 and 1703 Seismic Sequences (Central Italy) (2024)
    Seismological Society of America
    Details
    Publication Date: 2024-03-12
    Description: The macroseismic source parameters of earthquakes occurring within a sequence are strongly influenced by cumulative damage effects. When we deal with historical seismic sequences, in addition to the cumulative intensities, other intrinsic uncertainties due to the scarcity and indeterminacy of sources come into play. These issues imply that the parameterizations of the single earthquakes within a historical seismic sequence are not univocal and that all the uncertainties that are addressed when assessing macroseismic intensity should be carefully considered in the parameter estimation. In the light of these considerations, we performed some tests on the 2016–2017 and 1703 seismic sequences, which occurred in the same area in central Italy, to compute the macroseismic source parameters by means of two independent methods. Results show that the cumulative effects arising from multiple damaging earthquakes can cause biases in the intensity assessments, which affect the computed magnitude and epicentral locations. To reduce bias in macroseismic intensities due to cumulative damage, we illustrate a simple procedure, called cumulative intensity subtraction (CIS), which consists in discarding the localities strongly damaged by the early earthquakes of a sequence from the intensity distributions used for computing the macroseismic source parameters of the subsequent earthquakes. The outcomes show that, for the 2016 seismic sequence, the CIS approach provides locations in agreement with the instrumental epicenters and with the causative faults. For the 1703 sequence, the CIS approach along with explicit accounting for the indeterminacy in intensity assignments give a range of equally plausible solutions. The CIS represents an exploration of a simple strategy that stems from an attempt to give significance to macroseismic intensity in the presence of cumulative damage.
    Description: Published
    Description: 759–774
    Description: OST4 Descrizione in tempo reale del terremoto, del maremoto, loro predicibilità e impatto
    Description: JCR Journal
    Keywords: macroseismic intesity ; cumulative effects ; microseismic source parameters ; 04.06. Seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 3
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    Comment on “A Seismic Moment Magnitude Scale” by Ranjit Das, Mukat Lal Sharma, Hans Raj Wason, Deepankar Choudhury, and Gabriel Gonzalez (2024)
    Seismological Society of America
    In:  Das, R., M. L. Sharma, H. R. Wason, D. Choudhury, and G. Gonzales (2019). A seismic moment magnitude scale, Bull Seismol. Soc. Am. 109, no. 4, 1542–1555, doi: 10.1785/0120180338.
    Details
    Publication Date: 2024-05-21
    Description: Moment magnitude Mw was first defined by Hiroo Kanamori in the late 1970s, when the availability of new force balance seismometers made it possible to measure the seismic moment M0 with virtually no limits in the frequency passband. For this reason, Mw does not become saturated even for the largest earthquakes ever recorded. Mw has been chosen in such a way that it coincides best with the previous definitions of magnitude (Ms, ML, mb, etc.) on certain ranges of values but can deviate significantly from them within other ranges. A few years ago, Das and colleagues proposed a new moment magnitude scale Mwg with the aim of better reproducing the values of mb and Ms over their entire range and to better predict the energy ES radiated by earthquakes. We show that there was no need to define such a new scale and that Mwg is not even optimal to achieve the goal of matching ES.
    Description: In press
    Description: OST2 Deformazione e Hazard sismico e da maremoto
    Description: JCR Journal
    Keywords: earthquake magnitude ; moment magnitude scale ; 04.06. Seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 4
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    Comment on “Earthquake Magnitude Conversion Problem” by Ranjit Das, H. R. Wason, Gabriel Gonzalez, M. L. Sharma, Deepankar Choudhury, Conrad Lindholm, Narayan Roy, and Pablo Salazar (2024)
    Seismological Society of America
    In:  "Earthquake Magnitude Conversion Problem” by Ranjit Das, H. R. Wason, Gabriel Gonzalez, M. L. Sharma, Deepankar Choudhury, Conrad Lindholm, Narayan Roy, and Pablo Salazar
    Details
    Publication Date: 2024-05-21
    Description: Similar to the previous ones, the latest paper by Das and Colleagues (Das et al.,2018) on the application of the general orthogonal regression (GOR) method (Fuller, 1987; Castellaro et al.,2006), for the conversions between different types of earthquake magnitudes, is a collection of incorrect or undemonstrated assertions, most of which have already been pointed out in several contributions that have been published in the last few years (Gasperini and Lolli, 2014a, b; Gasperini et al., 2015, 2018; Pujol, 2018). We recall below only some of them. According to the recent seismological literature, we use here the term “GOR” to indicate the errors-in variable regression method described by Fuller (1987), even if such term is not fully in line with mathematical statistics as orthogonality is only given for equal errors of the dependent and independent variables.
    Description: Published
    Description: 1366-1369
    Description: OST2 Deformazione e Hazard sismico e da maremoto
    Description: JCR Journal
    Keywords: 04.06. Seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 5
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    A Reliable Procedure to Estimate the Rupture Propagation Directions from Source Directivity: The 2016–2018 Central Italy Seismic Sequence (2024)
    Seismological Society of America
    Details
    Publication Date: 2024-05-22
    Description: We present a new approach to estimate the predominant direction of rupture propagation during a seismic sequence. A fast estimation of the rupture propagation direction is essential to knowthe azimuthal distribution of shaking around the seismic source and the associated risks for the earthquake occurrence. The main advantage of the proposed method is that it is conceptually reliable, simple, and fast (near real time). The approach uses the empirical Green’s function technique and can be applied directly to the waveforms without requiring the deconvolution of the instrumental response and without knowing a priori the attenuation model and the orientation of the activated fault system. We apply the method to the 2016–2017 Amatrice-Visso-Norcia high-energy and long-lasting earthquake series in central Italy,which affected a large area up to 80 kmalong strike, withmore than 130,000 events of small-to-moderate magnitude recorded until the end of August 2022. Most of the selected events analyzed in this study have a magnitude greater than 4.4 and only four seismic events have a magnitude in the range of 3.3–3.7. Our results show that the complex activated normal fault system has a rupture direction mainly controlled by the pre-existing normal faults and by the orientation of the reactivated faults. In addition, the preferred direction of rupture propagation is also controlled by the presence of fluid in the pre-existing structural discontinuities. We discuss the possible role of fluids as a cause of bimaterial interface. Another important finding from our analysis is that the spatial evolution of seismicity is controlled by the directivity.
    Description: Published
    Description: 1912–1924
    Description: JCR Journal
    Keywords: directivity ; 04.06. Seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 6
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    Imaging Upper-Mantle Anisotropy with Transdimensional Bayesian Monte Carlo Sampling (2024)
    Seismological Society of America
    Details
    Publication Date: 2024-06-13
    Description: Underdetermination is a condition affecting all problems in seismic imaging. It manifests mainly in the nonuniqueness of the models inferred from the data. This condition is exacerbated if simplifying hypotheses like isotropy are discarded in favor of more realistic anisotropic models that, although supported by seismological evidence, require more free parameters. Investigating the connections between underdetermination and anisotropy requires the implementation of solvers which explore the whole family of possibilities behind nonuniqueness and allow for more informed conclusions about the interpretation of the seismic models. Because these aspects cannot be investigated using traditional iterative linearized inversion schemes with regularization constraints that collapse the infinite possible models into a unique solution, we explore the application of transdimensional Bayesian Monte Carlo sampling to address the consequences of underdetermination in anisotropic seismic imaging. We show how teleseismic waves of P and S phases can constrain upper‐mantle anisotropy and the amount of additional information these data provide in terms of uncertainty and trade‐offs among multiple fields.
    Description: Published
    Description: 1214–1226
    Description: OST1 Alla ricerca dei Motori Geodinamici
    Description: JCR Journal
    Keywords: 04.06. Seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 7
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    The Community Stress-Drop Validation Study—Part I: Source, Propagation, and Site Decomposition of Fourier Spectra (2023)
    Seismological Society of America
    Details
    Publication Date: 2023-10-03
    Description: In part 1, we run multiple GIT decomposition for different choices of model assumptions, namely three different window duration for Fourier calculation, two different parametrization of the attenuation, two different site constraints. We also considered different source models (Brune, Boatwright, Brune with kappa_source) and different approaches to estimate uncertainties of source parameters (i.e., considering the covariance matrix, Monte Carlo sampling of the residual distribution, model selection with threshold based on F-test).
    Description: As part of the community stress-drop validation study initiative, we apply a spectral decomposition approach to isolate the source spectra of 556 events occurred during the 2019 Ridgecrest sequence (Southern California). We perform multiple decompositions by introducing alternative choices for some processing and model assumptions, namely: three different S-wave window durations (i.e., 5 s, 20 s, and variable between 5 and 20 s); two attenuation models that account differently for depth dependencies; and two different site amplification constraints applied to restore uniqueness of the solution. Seismic moment and corner frequency are estimated for the Brune and Boatwright source models, and an extensive archive including source spectra, site amplifications, attenuation models, and tables with source parameters is disseminated as the main product of the present study. We also compare different approaches to measure the precision of the parameters expressed in terms of 95% confidence intervals (CIs). The CIs estimated from the asymptotic standard errors and from Monte Carlo resampling of the residual distribution show an almost one-to-one correspondence; the approach based on model selection by setting a threshold for misfit chosen with an F-ratio test is conservative compared to the approach based on the asymptotic standard errors. The uncertainty analysis is completed in the companion article in which the outcomes from this work are used to compare epistemic uncertainty with precision of the source parameters.
    Description: Published
    Description: 1980–1991
    Description: 3T. Fisica dei terremoti e Sorgente Sismica
    Description: JCR Journal
    Keywords: source parameters ; GIT ; uncertainties ; moment magnitude ; corner frequency ; 04.06. Seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 8
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    Comment on “High-Definition Mapping of the Gutenberg–Richter b-Value and Its Relevance: A Case Study in Italy” by M. Taroni, J. Zhuang, and W. Marzocchi (2023)
    Seismological Society of America
    In:  Taroni, M., J. Zhuang, and W. Marzocchi (2021). High-definition mapping of the Gutenberg–Richter b-value and its relevance: A case study in Italy, Seismol. Res. Lett. 92, 3778–3784, doi: 10.1785/0220210017.
    Details
    Publication Date: 2023-02-21
    Description: Taroni et al. (2021) published a statistical framework to reliably estimate the b-value and its uncertainties, with the goal being the interpretation in a seismotectonic context and improving earthquake forecasting capabilities. In this comment, we show that the results presented for the Italian region and the conclusions drawn by the authors, are heavily biased due to quarry-blast events in the Italian earthquake catalog used in the analysis. Without removing this anthropogenic component in the data, a meaningful analysis of the earthquake- size distribution for natural seismicity is, in our opinion, not possible. This comment highlights the need for basic data quality analysis before sophisticated statistical tools are applied to a dataset.
    Description: European Union’s Horizon 2020 research and innovation program under Grant Agreement Number 821115 Pianeta Dinamico-Working Earth INGV-MUR project.
    Description: Published
    Description: 1089-1094
    Description: 5T. Sismologia, geofisica e geologia per l'ingegneria sismica
    Description: JCR Journal
    Keywords: 04.06. Seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 9
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    Evaluation of the Event Detection Level of the Cuban Seismic Network (2023)
    Seismological Society of America
    Details
    Publication Date: 2023-01-23
    Description: The detection level of a seismic network is a measure of its effective ability to record small earthquakes in a given area. It can vary in both space and time and depends on several factors such as meteorological conditions, anthropic noise, local soil conditions—all factors that affect the seismic noise level—as well as the quality and operating condition of the instruments. The ability to estimate the level of detection is of tremendous importance both in the design of a new network and in determining whether a given network can recognize seismicity consistently or needs to be improved in some of its parts. In this article, we determine the detection level of the Cuban seismic network using the empirically estimated seismic noise spectral level at each station site and some theoretical relationships to predict the signal amplitude of a seismic event at individual stations. The minimum local detectable magnitude thus depends on some network parameters such as the signal‐to‐noise ratio and the number of stations used in the calculation. We also demonstrate the effectiveness of our predictions by comparing the estimated detection level with those empirically determined from one year of data (i.e., the year 2020) of the Cuban seismic catalog. Our analysis shows, on the one hand, in which areas the current Cuban network should be improved, also depending on the regional pattern of faults, and, on the other hand, indicates the magnitude threshold that can be assumed homogeneously for the catalog of Cuban earthquakes in 2020. Because the adopted method can use current measurements of the seismic noise level (e.g., daily), the proposed analysis can also be configured for continuous monitoring of network state quality.
    Description: Published
    Description: 2048-2062
    Description: 5T. Sismologia, geofisica e geologia per l'ingegneria sismica
    Description: 1IT. Reti di monitoraggio e sorveglianza
    Description: JCR Journal
    Keywords: seismic monitoring ; detection ; cuba ; seismic network ; Event Detection Level ; 04.06. Seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 10
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    Minimum 1D Vp and Vp/Vs Models and Hypocentral Determinations in the Central Mediterranean Area (2023)
    Seismological Society of America
    Details
    Publication Date: 2023-03-01
    Description: Minimum 1D velocity models and station corrections have been computed for the central Mediterranean area using two main data sets. The first one consists of accurate first arrival‐time readings from 103 seismic events with magnitude (ML)≥3.5 recorded by the Italian National Seismic Network (RSN) and the AlpArray Seismic Network (AASN) in the period 2014–2021. Earthquakes were selected on the basis of their spatial distribution, epicentral distance to the nearest seismic station, and maximum distance traveled by Pn and Sn phases. This fine selection of high‐quality data combined with the spatial density of the AlpArray seismic stations was decisive in obtaining high resolution for upper mantle velocity, especially in the Alpine belt. To obtain a denser coverage of crustal rays, we extended the first data set with P and S arrivals of local earthquakes from Istituto Nazionale di Geofisica e Vulcanologia (INGV) bulletin data (2016–2018). A total of 75,807 seismic phases (47,183 P phases and 28,264 S phases) have been inverted to calculate best‐fit 1D velocity models, at regional and local scales. We then test the performance of the optimized velocity models by relocating the last four years of seismicity recorded by INGV (period 2017–2020). The computed velocity models are very effective for routine earthquake location, seismic monitoring, source parameter modeling, and future 3D seismic tomography.
    Description: Published
    Description: 2670--2685
    Description: 4T. Sismicità dell'Italia
    Description: JCR Journal
    Keywords: geophysics ; velocity models ; Italian seismicity ; central mediterranean area ; 04. Solid Earth ; 04.06. Seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 11
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    The Dependence on the Moho Depth of the b-Value of the Gutenberg–Richter Law (2023)
    Seismological Society of America
    Details
    Publication Date: 2023-03-31
    Description: We investigate the dependence of the Gutenberg–Richter b parameter on the crustal thickness quantified by the Moho depth, for nine different regional catalogs. We find that, for all the catalogs considered in our study, the b‐value is larger in areas presenting a thicker crust. This result appears in apparent contradiction with previous findings of a b decreasing with the focal depth. However, both the results are consistent with acoustic emission experiments, indicating a b‐value inversely proportion to the applied differential stress. Our results can be indeed interpreted as the signature of a larger stress concentration in areas presenting a thinner crust. This is compatible with the scenario where postseismic deformation plays a central role in stress concentration and in aftershock triggering.
    Description: Published
    Description: 1921–1934
    Description: 6T. Studi di pericolosità sismica e da maremoto
    Description: JCR Journal
    Keywords: b-value ; 04.06. Seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 12
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    Fine‐Scale Structure of the 2016–2017 Central Italy Seismic Sequence From Data Recorded at the Italian National Network (2020)
    Wiley
    Details
    Publication Date: 2020-05-25
    Description: We explore the three‐dimensional structure of the 2016–2017 Central Italy sequence using ~34,000 ML ≥ 1.5 earthquakes that occurred between August 2016 and January 2018. We applied cross‐correlation and double‐difference location methods to waveform and parametric data routinely produced at the Italian National Institute of Geophysics and Volcanology. The sequence activated an 80 km long system of normal faults and near‐horizontal detachment faults through the MW 6.0 Amatrice, the MW 5.9 Visso, and the MW 6.5 Norcia mainshocks and aftershocks. The system has an average strike of N155°E and dips 38°–55° southwestward and is segmented into 15–30 km long faults individually activated by the cascade of MW ≥ 5.0 shocks. The two main normal fault segments, Mt. Vettore‐Mt. Bove to the North and Mt. della Laga to the South, are separated by an NNE‐SSW‐trending lateral ramp of the Sibillini thrust, a regional structure inherited from the previous compressional tectonic phase putting into contact diverse lithologies with different seismicity patterns. Space‐time reconstruction of the fault system supports a composite rupture scenario previously proposed for the MW 6.5 Norcia earthquake, where the rupture possibly propagated also along an oblique portion of the Sibillini thrust. This dissected set of normal fault segments is bounded at 8–10 km depth by a continuous 2 km thick seismicity layer of extensional nature slightly dipping eastward and interpreted as a shear zone. All three mainshocks in the sequence nucleated along the high‐angle planes at significant distance from the shear zone, thus complicating the interpretation of the mechanisms driving strain partitioning between these structures.
    Description: Published
    Description: e2019JB018440
    Description: 3T. Sorgente sismica
    Description: JCR Journal
    Keywords: normal fault ; shear zone ; fault segmentation ; apennines ; 04.06. Seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 13
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    Homogenization in Terms of Mw of Local Magnitudes of Italian Earthquakes That Occurred before 1981 (2018)
    Seismological Society of America
    Details
    Publication Date: 2018-02-16
    Description: In the last two decades, several studies addressed the revaluation and homogenization of the Italian instrumental seismic catalog, but all of them refer to the time interval from 1981, that is, the starting year of the Catalogo Strumentale dei Terremoti Italiani (CSTI). At the time, the CSTI was conceived as the continuation of the catalog of the Progetto Finalizzato Geodinamica (PFG) but, over time, the PFG catalog was almost totally forgotten, and presently it is even difficult to obtain because it is not provided by any website. In this work, we integrate a genuine copy of PFG, with additional locations from the bulletins of the Istituto Nazionale di Geofisica (ING, now known as INGV) and of the International Seismological Centre (ISC) and with local magnitudes from two couples of Wood–Anderson (WA) seismometers operational in Italy in the 1970s and 1980s, mostly derived from a careful scrutiny of paper bulletins of the Osservatorio Geofisico Sperimentale (OGS) and of the ING. We restrict our analysis to the time interval from 1960 to 1980 because, based on various evidence, we can infer that within such period most instrumental magnitudes reported by the PFG catalog are reasonably coherent with the Richter’s definition. Magnitudes provided by WA stations and other data sources are calibrated with respect to Mw by general orthogonal regressions. The final catalog from 1960 to 1980 contains 8536 earthquakes, of which we compute a true or proxy Mw magnitude with related uncertainty for 6407. The analysis of the frequency–magnitude distribution indicates completeness for about Mw ≥4:0. This work extends the time coverage of the Italian instrumental catalog to about 55 yrs before the present, allowing the statistical study of some important seismic periods that occurred, for example, in 1962 (Irpinia), 1968 (Belice Valley), 1976 (Friuli), 1979 (Umbria), and 1980 (Irpinia).
    Description: Published
    Description: 481–492
    Description: 4IT. Banche dati
    Description: JCR Journal
    Keywords: local magnitude ; magnitude homogenization ; 04.06. Seismology
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  • 14
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    An Almost Fair Comparison Between Earthworm and SeisComp3 (2018)
    Seismological Society of America
    Details
    Publication Date: 2018-03-12
    Description: The paper has not any abstract
    Description: Published
    Description: 720-727
    Description: 2T. Sorgente Sismica
    Description: 1IT. Reti di monitoraggio
    Description: JCR Journal
    Keywords: Earthquake ; Monitoring ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
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  • 15
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    Gempa Nusantara: A New Digital Database of Felt Intensity for Historical Earthquakes in the Indonesian Archipelago (2018)
    Seismological Society of America
    Details
    Publication Date: 2021-11-08
    Description: Seismicity during Dutch colonial rule in Indonesia between 1800 and 1939 is poorly catalogued with existing summaries (e.g. Newcomb & McCann, 1987) too brief for further quantitative assessment such as the calculation of intensity magnitudes (MI). We focus on this period in Indonesian history, collating and analysing reports from official documents and newspapers from the erstwhile Dutch East Indies. We scrutinize these for macroseismic intensity using the European Macroseismic Scale (EMS-98). This scale is closely related to the Modified Mercalli Intensity (MMI) scale but is associated with better guidelines with which to assess damage to built-up environments. Our approach enables us to uniformly assess felt intensities from Sumatra, Java, Bali, and Borneo along with instances of perceived shaking from the eastern Indonesian archipelago, and from the Malay peninsula including Singapore. Building upon previous work (Martin et al., 2015), we corelate our data, when possible, with regional, and teleseismic instrumental observations. This allows us to discriminate, for example, a possible M~6 doublet in the region of South Sumatra in 1908. Felt effects in west Malaysia and Singapore from numerous earthquakes in Sumatra were also collected, and unexpectedly, we found two widely felt earthquakes in Singapore in 1922 that likely originated in the region of the southern Malaya peninsula. All our observations contribute to a database named Gempa Nusantara which roughly translates to earthquakes (gempa) in the Indonesian archipelago (nusantara) in Bahasa Indonesia. This database uses a web application called MIDOP (Macroseismic Intensity Data Online Publisher) which is an open-source program written in PHP that has been previously utilized to publish intensity data in Europe (Locati et al., 2014). In our study we extend the capabilities of the MIDOP application further, particularly in equatorial regions, and use it to manage our data from historical Indonesian earthquakes.
    Description: Earth Observatory of Singapore, Nanyang Technological University
    Description: Published
    Description: Miami, Florida, United States of America
    Description: 4T. Sismicità dell'Italia
    Description: 5T. Sismologia, geofisica e geologia per l'ingegneria sismica
    Keywords: historical seismology ; macroseismic intensity ; 04. Solid Earth ; 04.04. Geology ; 04.06. Seismology ; 05.02. Data dissemination
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 16
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    The Ongoing Seismic Sequence at the Pollino Mountains, Italy (2015)
    Seismological Society of America
    Details
    Publication Date: 2020-11-26
    Description: A sequence of thousands of small to moderate earthquakes has been occurring since spring 2010 in the Pollino Mountains area, southern Italy, where a seismic gap was previously hypothesized by paleoseismological evidence associated with the lack of major earthquakes in historical catalogs.
    Description: Published
    Description: 955-962
    Description: 2T. Tettonica attiva
    Description: JCR Journal
    Description: restricted
    Keywords: seismic sequence ; earthquake location ; focal mechanism ; 04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 17
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    Operational (short-term) earthquake loss forecasting in Italy (2015)
    Seismological Society of America
    Details
    Publication Date: 2021-06-21
    Description: The seismological community is currently developing operational earthquake forecasting (OEF) systems that aim to estimate, based on continuous ground motion recording by seismic networks, the rates of events exceeding a certain magnitude threshold in an area of interest and in a short-period of time (days to weeks); i.e., the seismicity. OEF may be possibly used for short-term seismic risk management in regions affected by seismic swarms only if its results may be the input to compute, in a probabilistically sound manner, consequence-based risk metrics. The present paper reports the investigation about feasibility of short-term risk assessment, or operational earthquake loss forecasting (OELF), in Italy. The approach is that of performance-based earthquake engineering, where the loss rates are computed by means of hazard, vulnerability, and exposure. The risk is expressed in terms of individual and regional measures, which are based on short-term macroseismic intensity, or ground motion intensity, hazard. The vulnerability of the built environment relies on damage probability matrices empirically calibrated for Italian structural classes, and exposure data in terms of buildings per vulnerability class and occupants per building typology. All vulnerability and exposure data are at the municipality scale. The procedure set-up, which is virtually independent on the seismological model used, is implemented in an experimental OELF system, which continuously process OEF information to produce weekly nationwide risk maps. This is illustrated by a retrospective application to the 2012 Pollino (southern Italy) seismic sequence, which provides insights on the capabilities of the system and on the impact, on short-term risk assessment, of the methodology currently used for OEF in Italy.
    Description: Published
    Description: 2286-2298
    Description: 3T. Pericolosità sismica e contributo alla definizione del rischio
    Description: JCR Journal
    Description: reserved
    Keywords: operational earthquake forecasting ; seismic risk ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk
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    Macroseismic Intensity Assessment Method for Web Questionnaires (2015)
    Seismological Society of America
    Details
    Publication Date: 2021-03-04
    Description: Macroseismic investigation with data collected through web- based questionnaires is today routinely applied by most impor- tant seismological institutions, such as the U.S. Geological Survey (http://earthquake.usgs.gov/earthquakes/dyfi/; last accessed December 2014), British Geological Survey (http://www. earthquakes.bgs.ac.uk/questionnaire/EqQuestIntro.html; last accessed December 2014), European-Mediterranean Seismological Centre (http://www.emsc-csem.org/Earthquake/Contribute/ choose_earthquake.php?lang=en; last accessed December 2014), Schweizerische Erdbebendienst (http://www.seismo.ethz. ch/eq/detected/eq_form/index_EN; last accessed December 2014), Bureau Central Sismologique Français (http://www .seisme.prd.fr/english.php; last accessed December 2014), and the New Zealand GeoNet project (http://www.geonet.org.nz/ quakes/; last accessed December 2014). The wide diffusion of Internet and the citizen collaboration (crowdsourcing) allow documentation of information on seismic effects and production of a macroseismic field with low costs and almost in real time. Transformation from qualitative information (as given by ques- tionnaires) to numerical quantification is a crucial issue. In the traditional evaluation of intensity, experts used to work through a complex comparison of effects basically driven by personal expe- rience. The major problem with this approach concerns the dif- ficulty in verifing and reproducing the evaluation process due to the lack of a detailed explanation of the employed workflow and to the large variability of possible cases. On the other hand, an automatic method for the estimation of macroseismic intensities needs to be completely well defined and specified in order to be reproducible and verifiable. For these reasons, this paper presents a comprehensive explanation of our intensity assessment method. A useful automatic method for intensity assessment should be computationally fast and strictly follow the macroseismic scales. To meet these requirements in 2010, we proposed a method that firstly quantified the effects using additive scores associated with each answer of the questionnaire item and then determined an intensity estimate for each questionnaire (Sbarra et al., 2010). After a trial period and having collected more than 500,000 questionnaires, we were able to thoroughly test the method. As a result of this testing, we describe here a new improved method that takes into account further factors, such as the situation and the location of the observer (Sbarra et al., 2012, 2014), to obtain a more accurate estimate of the macroseismic intensity degree at the municipality level. In this paper, we show some applications of our method with reference to the Mercalli–Cancani–Sieberg (MCS) scale, because this scale has long been used with Italian earthquakes and allows easy comparison between these intensities and other traditional ones.
    Description: Published
    Description: 985-990
    Description: 3T. Pericolosità sismica e contributo alla definizione del rischio
    Description: 5T. Sorveglianza sismica e operatività post-terremoto
    Description: 4IT. Banche dati
    Description: JCR Journal
    Description: reserved
    Keywords: Macroseismics ; intensity ; questionnaires ; attenuation ; 04. Solid Earth::04.06. Seismology::04.06.04. Ground motion ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring ; 05. General::05.01. Computational geophysics::05.01.05. Algorithms and implementation
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    Accounting for Epistemic Uncertainty in PSHA: Logic Tree and Ensemble Modeling (2015)
    Seismological Society of America
    Details
    Publication Date: 2021-05-12
    Description: Any trustworthy probabilistic seismic hazard analysis (PSHA) has to account for the intrinsic variability of the system (aleatory variability) and the limited knowledge of the system itself (epistemic uncertainty). The most popular framework for this purpose is the logic tree. Notwithstanding its vast popularity, the logic tree outcomes are still interpreted in two different and irreconcilable ways. In one case, practitioners claim that the mean hazard of the logic tree is the hazard and the distribution of all outcomes does not have any probabilistic meaning. On the other hand, other practitioners describe the seismic hazard using the distribution of all logic tree outcomes. In this paper, we explore in detail the reasons of this controversy about the interpretation of logic tree, showing that the distribution of all outcomes is more appropriate to provide a joined full description of aleatory variability and epistemic uncertainty. Then, we provide a more general framework - that we name ensemble modeling - in which the logic tree outcomes can be embedded. In this framework, the logic tree is not a classical probability tree, but it is just a technical tool that samples epistemic uncertainty. Ensemble modeling consists of inferring the parent distribution of the epistemic uncertainty from which this sample is drawn. Ensemble modeling offers some remarkable additional features. First, it allows a rigorous and meaningful validation of any PSHA; this is essential if we want to keep PSHA into a scientific domain. Second, it provides a proper and clear description of the aleatory variability and epistemic uncertainty that can help stakeholders to appreciate the whole range of uncertainties in PSHA. Third, it may help to reduce the computational time when the logic tree becomes computationally intractable because of the too many branches.
    Description: Published
    Description: 2151-2159
    Description: 1SR. TERREMOTI - Servizi e ricerca per la Società
    Description: JCR Journal
    Description: reserved
    Keywords: seismic hazard ; logic tree ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk
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    Difference in shaking intensity between short and tall buildings: known and new findings (2015)
    Seismological Society of America
    Details
    Publication Date: 2021-03-04
    Description: We investigate the influence of building height on the ability of people to feel earthquakes and observe that, in an urban area, short and tall buildings reach different levels of excitation. We quantify this behavior by analyzing macroseismic reports collected from individuals through the Internet, focusing on transitory effects, therefore in the elastic regime during recent earthquakes in Italy in the local magnitude (ML) range of 3 to 5.9. We find a maximum difference of 0.6 intensity units between the top floors of tall (7–10 stories) and short (1–2 stories) buildings at the highest considered magnitudes. As expected, tall buildings experience greater shaking than short buildings during large earthquakes at large source distances. However, we observe the opposite behavior at close distances when the ML is less than 3.5. These results can be explained by considering the different spectra radiated by small and large earthquakes and the different fundamental mode resonances of buildings (i.e., shorter buildings have higher resonance frequencies and vice versa). Using idealized building models excited by real acceleration time histories, we compute synthetic accelerograms on the top floors of short and tall buildings, and confirm the trend of the observed differences in felt intensities.
    Description: Published
    Description: 1803-1809
    Description: 3T. Pericolosità sismica e contributo alla definizione del rischio
    Description: JCR Journal
    Description: reserved
    Keywords: Macroseismics ; intensity ; building height ; 04. Solid Earth::04.06. Seismology::04.06.04. Ground motion ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
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    Adaptive daily forecasting of seismic aftershock hazard (2015)
    Seismological Society of America
    Details
    Publication Date: 2021-06-22
    Description: Seismic aftershock-hazard analysis is one of the first steps toward estab- lishing an integrated risk-based decision-making support framework for emergency management in the event of an ongoing aftershock sequence. This work focuses on providing adaptive daily forecasts of the mean daily rate of exceeding various spectral acceleration values (the aftershock hazard). Two well-established earthquake- occurrence models suitable for daily seismicity forecasts associated with the evolution of an aftershock sequence, namely, the modified Omori’s aftershock model (MO) and the epidemic-type aftershock sequence (ETAS) are adopted. An adaptive and evolution- ary MO-based aftershock occurrence model with distinct spatial and temporal compo- nents is proposed. In this model, the parameters deciding the temporal decay are updated based on the data provided by the ongoing aftershock sequence. This model adopts an evolutionary spatial seismicity pattern loosely based on spatial clustering of aftershock events in the sequence. Bayesian updating is also employed to provide sequence-based parameter estimates for a given ground-motion prediction model. Daily forecasts of the mean rate of exceedance of various spectral acceleration levels are calculated based on alternative occurrence models and the updated ground-motion prediction relation. As a numerical example, daily forecasts of the aftershock-hazard curve are obtained for the L’Aquila aftershock sequence based on the MO-based and ETAS occurrence models, and an updated version of the Sabetta and Pugliese (1996) ground-motion prediction model. These daily hazard forecasts are then compared with the observed daily rates of exceeding various spectral acceleration thresholds.
    Description: Published
    Description: 145 – 161
    Description: 3T. Pericolosità sismica e contributo alla definizione del rischio
    Description: JCR Journal
    Description: reserved
    Keywords: earthquake forecast ; aftershock ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk
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    Operational earthquake forecasting can enhance earthquake preparedness (2015)
    Seismological Society of America
    Details
    Publication Date: 2021-06-25
    Description: We cannot yet predict large earthquakes in the short term with much reliability and skill, but the strong clustering exhibited in seismic sequences tells us that earthquake probabilities are not constant in time; they generally rise and fall over periods of days to years in correlation with nearby seismic activity. Opera- tional earthquake forecasting (OEF) is the dissemination of authoritative information about these time-dependent proba- bilities to help communities prepare for potentially destructive earthquakes. The goal of OEF is to inform the decisions that people and organizations must continually make to mitigate seismic risk and prepare for potentially destructive earthquakes on time scales from days to decades. To fulfill this role, OEF must provide a complete description of the seismic hazard—ground-motion exceedance probabilities as well as short-term rupture probabilities—in concert with the long-term forecasts of probabilistic seismic-hazard analysis (PSHA).
    Description: Published
    Description: 955-959
    Description: 3T. Pericolosità sismica e contributo alla definizione del rischio
    Description: JCR Journal
    Description: reserved
    Keywords: Operational earthquake forecasting ; seismic preparedness ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk
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  • 23
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    Shaking scenarios from multiple source models shed light on the Mw 7 Calabria 8 September 1905 earthquake (S Italy) (2015)
    Seismological Society of America
    Details
    Publication Date: 2017-04-04
    Description: The destructive earthquake (M 7) that struck western Calabria (southern Italy) on 8 September 1905 profoundly hit a broad region, also generating a feeble tsunami. For all the damage it caused, this event was as much studied as not fully explained. Literature source models are numerous and diverse, in fault geometry, location, and associated magnitude. They also differ in nature, since these solutions are either field- based, or deriving from tsunami modeling, and macroseismic data inversion. Most. Neither all of these literature source models are not consistent with the damage pattern caused by the 1905 earthquake. To contribute to the identification of the seismogenic source of this destructive event, we performed a series of ground shaking scenarios, based on different faults that various authors associated with this event. The only documented data available suitable for our comparative purposes are the macroseismic intensities associated with localities affected by the event. We transformed the values of ground motion we computed for the same datapoints into intensities. We then attributed a quantitative fit to each modeled seismogenic source, evaluated with the quadratic sum of residuals between observed and calculated intensities. Our results show that two out of 7 literature source models are compatible with the damage distribution caused by the 1905 earthquake. The different parameters and boundary conditions constraining these two solutions suggest that either seismogenic source should include further complexities. Alternatively, since these two sources are antithetic and partially form a graben, they might have kinematically interacted, if passively, on 8 September 1905.
    Description: Project ISTEGE: “Indagine Sismotettonica del TErremoto dell'8 Settembre 1905 (Mw 7.4) nel Golfo di Sant'Eufemia – offshore tirrenico calabrese”, supported by OGS (Istituto Nazionale di Oceanografia e di Geofisica Sperimentale); Project RITMARE, funded by Dipartimento della Protezione Civile (Italy's National Civil Protection).
    Description: Published
    Description: 912-927
    Description: 3T. Pericolosità sismica e contributo alla definizione del rischio
    Description: JCR Journal
    Description: reserved
    Keywords: Shaking scenarios ; Seismogenic sources ; 1905 earthquake ; Southern Italy ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics ; 04. Solid Earth::04.06. Seismology::04.06.04. Ground motion ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk ; 05. General::05.01. Computational geophysics::05.01.04. Statistical analysis
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  • 24
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    Faulting and Ancient Earthquakes at Sybaris Archaeological Site, Ionian Calabria, Southern Italy (2015)
    Seismological Society of America
    Details
    Publication Date: 2020-02-24
    Description: The Sybaris archaeological site, founded by the Greeks in 720 B.C., is located within the Sibari Plain near the Crati River mouth (Ionian northern Calabria, southern Italy), in an almost flat and low-lying area (Fig. 1). The plain is bounded by the Pollino chain to the north and by the Sila massif and the northern Crati basin to the south and west. From a seismotectonic point of view, Sybaris is located inferences the northeastern Calabrian arc, the tectonic evolution of which is controlled by slow north-northwest/south-southeast convergence between the Eurasian and African–Adriatic continental plates (e.g., Gvirtzmann and Nur, 1999; Argnani, 2000; Jolivet and Faccenna, 2000). Throughout the Calabrian arc, complex dynamics associated with subduction and rollback have produced back-arc extension, widespread uplift, and relative subsidence in the major tectonic basins, including Sibari, where mainly normal seismogenic faults accommodate internal deformation. The interior of the Sibari Plain has a high seismogenic potential, and recently, on July 2010, theMt. Pollino chain area experienced a three-year seismic sequence with magnitudes up to 5.2 (Fig. 1), following 30 years of seismic quiescence. In contrast, low to moderate seismicity characterizes the eastern half of the plain closer to the Ionian Sea, where the archaeological site of Sybaris is located (Fig. 1). Although not well constrained, there is evidence for active compression in this portion of northern Calabria and the Ionian Sea, where mostly strike-slip faults aremapped (e.g., Frepoli and Amato, 2000; Galadini et al., 2001; Pondrelli et al., 2006; Scognamiglio et al., 2009; Comerci et al., 2013; Fig. 1), but significant uncertainty exists on locations, geometry, and age of these faults. The 2700-year long record of history stored in the archaeological site of Sybaris may have recorded the traces of earthquakes that occurred in the area by sealing their effects in the sediments and in the archaeological remains. An archaeoseismic study of the site constitutes a unique means to deepenour knowledge of the seismotectonic of the area. The recognition and characterization of the coseismic deformation affecting the structures of the Sybaris archaeological site is the objective of the present study. To identify past seismic deformation events at Sybaris, we proceeded with (1) a systematic survey of the deformed structures, (2) an analysis of the tectonic deformation, (3) the formulation of a hypothesis for tectonics and earthquakes inferences, and (4) constraints on the timing of the deformation based on archaeological stratigraphy and absolute dating.
    Description: Published
    Description: 245-254
    Description: 2T. Tettonica attiva
    Description: JCR Journal
    Description: restricted
    Keywords: Archaeo-seismology ; Active tectonics ; 04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution
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    The establishment of an operational earthquake forecasting system in Italy (2015)
    Seismological Society of America
    Details
    Publication Date: 2017-04-04
    Description: On 6 April 2009, an Mw 6.2 earthquake struck beneath the city of L’Aquila, central Italy. The shock created significant damage and caused more than 300 deaths in the city and environs. The event followed a seismic sequence that started at the begin- ning of the year, with its largest shock of M w 4.2 occurring on 30 March. The 6 April earthquake became infamous worldwide because seven experts, who attended a Grandi Rischi Commis- sion meeting on 31 March, were convicted of failing to properly warn the public about the possibility of the mainshock and were sentenced to six years in jail. A second trial is in process. We do not wish to further discuss this important case here (in- stead see Marzocchi, 2012 and the website http://processoaquila .wordpress.com/; last accessed June 2014); however, it illustrates the importance of providing authoritative scientific information about earthquake probabilities to the public and other users and serves as a catalyst for the scientific developments now underway in Italy.
    Description: Published
    Description: 961-969
    Description: 3T. Pericolosità sismica e contributo alla definizione del rischio
    Description: JCR Journal
    Description: reserved
    Keywords: Operational earthquake forecasting ; ensemble modeling ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk
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    Some Thoughts on Declustering in Probabilistic Seismic-Hazard Analysis (2015)
    Seismological Society of America
    Details
    Publication Date: 2017-04-04
    Description: In this paper, we discuss in depth, one of the basic procedures that stands behind probabilistic seismic-hazard analysis (PSHA), that is, the declustering of the seismicity rates. First, we explore the technical, scientific, and practical motivations that led to introducing the declustering of seismicity rates. Then, we show that for PSHA, declustering is essential only to minimize a spatial distortion of the earthquake occurrence process, but, conversely, it may lead to significant underestimation of the true seismic hazard. This underestimation precludes the possibility to test meaning- fully PSHA against real observations, and it may lead to underestimate the seismic risk, whenever seismic-hazard maps are used for risk assessment. Finally, we propose a methodology that can be used in PSHA to avoid this potential bias.
    Description: Published
    Description: 1838-1845
    Description: 3T. Pericolosità sismica e contributo alla definizione del rischio
    Description: JCR Journal
    Description: restricted
    Keywords: seismic hazard ; declustering ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk
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  • 27
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    Reply to “Comment on ‘Seismic Hazard Assessment (2003–2009) for the Italian Building Code’ by Massimiliano Stucchi, Carlo Meletti, Valentina Montaldo, Helen Crowley, Gian Michele Calvi, and Enzo Boschi” by Marco Mucciarelli and Dario Albarello (2015)
    Seismological Society of America
    Details
    Publication Date: 2017-04-04
    Description: In their lengthy comment on Stucchi et al. (2011), Mucciarelli and Albarello (2012) propose opinions on aspects of the study that have been discussed and reviewed in countless circumstances in Italy and internationally, from the very beginning (2003) to the end (2009) of our research.
    Description: Published
    Description: 2793-2794
    Description: 3T. Pericolosità sismica e contributo alla definizione del rischio
    Description: JCR Journal
    Description: restricted
    Keywords: Seismic hazard ; Italy ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk
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  • 28
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    Coseismic deformation and source modeling of the May 2012 Emilia (Northern Italy) earthquakes (2013)
    Seismological Society of America
    Details
    Publication Date: 2017-04-04
    Description: On May 20th, 2012, an ML 5.9 earthquake (Table 1) occurred near the town of Finale Emilia, in the Central Po Plain, Northern Italy (Figure 1). The mainshock caused 7 casualties and the collapse of several historical buildings and industrial sheds. The earthquake sequence continued with diminishing aftershock magnitudes until May 29th, when an ML 5.8 earthquake occurred near the town of Mirandola, ~12 km WSW of the mainshock (Scognamiglio et al., 2012). This second mainshock started a new aftershock sequence in this area, and increased structural damage and collapses, causing 19 more casualties and increasing to 15.000 the number of evacuees. Shortly after the first mainshock, the Department of Civil Protection (DPC) activated the Italian Space Agency (ASI), which provided post-seismic SAR Interferometry data coverage with all 4 COSMO-SkyMed SAR satellites. Within the next two weeks, several SAR Interferometry (InSAR) image pairs were processed by the INGV-SIGRIS system (Salvi et al., 2012), to generate displacement maps and preliminary source models for the emergency management. These results included continuous GPS site displacement data, from private and public sources, located in and around the epicentral area. In this paper we present the results of the geodetic data modeling, identifying two main fault planes for the Emilia seismic sequence and computing the corresponding slip distributions. We discuss the implication of this seismic sequence on the activity of the frontal part of the Northern Apennine accretionary wedge by comparing the co-seismic data with the long term (geological) and present day (GPS) velocity fields.
    Description: Published
    Description: 645-655
    Description: 1.1. TTC - Monitoraggio sismico del territorio nazionale
    Description: 1.9. Rete GPS nazionale
    Description: 1.10. TTC - Telerilevamento
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: restricted
    Keywords: Earthquake ; CFF analysis ; Tectonic ; geodynamic ; Seismic source ; Northern apennine (Italy) ; 04. Solid Earth::04.03. Geodesy::04.03.06. Measurements and monitoring ; 04. Solid Earth::04.03. Geodesy::04.03.07. Satellite geodesy ; 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 ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 05. General::05.01. Computational geophysics::05.01.01. Data processing ; 05. General::05.02. Data dissemination::05.02.02. Seismological data
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    Detection of Seismic Signals from Background Noise in the Area of Campi Flegrei: Limits of the Present Seismic Monitoring (2013)
    Seismological Society of America
    Details
    Publication Date: 2017-04-04
    Description: In the present paper, we will describe the field survey (Fig. 1) and the data analysis of an experiment carried out to put constraints on the magnitude detection threshold in the area of Campi Flegrei. Results show that seismic radiation emitted from VT seismic events at frequency lower than 2 Hz has a high detection threshold (minimum magnitude around 1.5). In the range between 2 and 20 Hz, VT events with magnitudes smaller than about 0.5 have a high probability to be undetected. This result indicates that noise reduction through borehole stations and/or small arrays is essential for an accurate seismic monitoring in the Campi Flegrei area.
    Description: Published
    Description: 190-198
    Description: 3.1. Fisica dei terremoti
    Description: JCR Journal
    Description: restricted
    Keywords: seismic noise ; magnitude detection ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis
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  • 30
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    Probabilistic Seismic Hazard Assessment: Combining Cornell-like approaches and data at sites through Bayesian inference (2013)
    Seismological Society of America
    Details
    Publication Date: 2017-04-04
    Description: The societal importance and implications of seismic hazard assessment forces the scientific community to pay an increasing attention to the evaluation of uncertainty, to provide accurate assessments. Probabilistic Seismic Hazard Assessment (PSHA) formally accounts for the natural variability of the involved phenomena, from seismic sources to wave propagation. Recently, an increasing attention is paid to the consequences that alternative modeling procedures have on hazard results. This uncertainty, essentially of epistemic nature, has been shown to have major impacts on PSHA results, leading to extensive applications of techniques like the Logic Tree. Here, we develop a formal Bayesian inference scheme for PSHA that allows, on one side, to explicitly account for all uncertainties and, on the other side, to consider a larger set of sources of information, from heterogeneous models to past data. This process decreases the chance of undesirable biases, and leads to a controlled increase of the precision of the probabilistic assessment. In addition, the proposed Bayesian scheme allows (i) the assignment of a ’subjective’ reliability to single models, without requirement of completeness or homogeneity, and (ii) a transparent and uniform evaluation of the ’strength’ of each piece of information used on the final results. The applicability of the method is demonstrated through the assessment of seismic hazard in the Emilia-Romagna region (Northern Italy), in which the results of a traditional Cornell-McGuire hazard model based on a Logic Tree are locally updated with the historical macroseismic records, to provide a unified assessment that accounts for both sources of information.
    Description: Published
    Description: 1709-1722
    Description: 4.2. TTC - Modelli per la stima della pericolosità sismica a scala nazionale
    Description: JCR Journal
    Description: restricted
    Keywords: Cornell-McGuire approach ; site intensity ; Bayesian inference ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk
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    Overview on the strong motion data recorded during the May-June 2012 Emilia seismic sequence (2013)
    Seismological Society of America
    Details
    Publication Date: 2017-04-04
    Description: 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.
    Description: Published
    Description: 629-644
    Description: 1.1. TTC - Monitoraggio sismico del territorio nazionale
    Description: JCR Journal
    Description: open
    Keywords: 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)
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  • 32
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    CRISIS2008: A Flexible Tool to Perform Probabilistic Seismic Hazard Assessment (2013)
    Seismological Society of America
    Details
    Publication Date: 2022-06-09
    Description: In the frame of the Italian research project INGV-DPC S2 (http://nuovoprogettoesse2.stru.polimi.it/), funded by the Dipartimento della Protezione Civile (DPC; National Civil Protection Department) within the agreement 2007-2009, a tool for probabilistic seismic hazard assessment (PSHA) was developed. The main goal of the project was to provide a flexible computational tool for PSHA; the requirements considered essential for the success of the project included: •ability to handle both stationary and non-stationary earthquake time-occurrence models; •ability to use ground-motion prediction models that are not parametric equations but probabilistic "footprints" of the intensities generated by earthquakes of known magnitude and focal characteristics. Usually, these footprints are results of ground motion simulations. Some commonly used programs (e.g., FRISK, by McGuire, 1978; SEISRISK III, by Bender and Perkins, 1987) and more recent and state-of-the-art tools (e.g. OpenSHA, by Field et al., 2003, http://www.opensha.org; OpenQuake, http://openquake.org) for PSHA were analyzed. It was decided to focus on CRISIS2007, which was already a mature and well known application (e.g., Kalyan Kumar and Dodagoudar, 2011; Teraphan et al., 2011; D’Amico et al., 2012; see also http://ecapra.org/CRISIS-2007), but also suitable for additional development and evolution since its source code is freely available on request. The computational tool resulted in an extensive redesign and renovation of the previous CRISIS2007 version. CRISIS is a computer program for PSHA, originally developed in the late 1980's using Fortran as programming language (Ordaz, 1991). In this format, still without a graphical user interface (GUI), it was distributed as part of SEISAN tools (Ottemöller et al., 2011). Ten years later, a GUI was constructed, generating what was called CRISIS99 (Ordaz, 1999). In this version, all the graphic features were written in Visual Basic, but the computation engine remained a Fortran dynamic link library. The reason for the use of mixed-language programming was that computations in Visual Basic were extremely slow. Around 2007 the program was upgraded, in view of the advantages offered by the object-oriented technologies. An object-oriented programming language was required and the natural choice was Visual Basic.Net. In the new version (called CRISIS2007), both the GUI and the computation engine were written in the same language. Finally, in the frame of the mentioned S2 project, starting from 2008, the program was split into two logical layers: core (CRISIS Core Library) and presentation (CRISIS2008). In addition, a new presentation layer was developed for accessing the same functionalities via Web (CRISISWeb). It is worth noting that CRISIS has been mainly written by people that are, at the same time, PSHA practitioners. Therefore, the development loop has been relatively short, and most of the modifications and improvements have been made to satisfy the needs of the developers themselves.
    Description: Italian Presidenza del Consiglio dei Ministri, Dipartimento della Protezione Civile (DPC).
    Description: Published
    Description: 495-504
    Description: 4.2. TTC - Modelli per la stima della pericolosità sismica a scala nazionale
    Description: JCR Journal
    Description: restricted
    Keywords: Seismic Hazard ; Seismology ; Probabilistic Seismic Hazard Assesment ; PSHA ; 04. Solid Earth::04.06. Seismology::04.06.02. Earthquake interactions and probability ; 04. Solid Earth::04.06. Seismology::04.06.04. Ground motion ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk
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  • 33
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    Influence of focal mechanism in probabilistic seismic hazard analysis (2012)
    Seismological Society of America
    Details
    Publication Date: 2017-04-03
    Description: An extension of probabilistic seismic hazard analysis is proposed to introduce a priori information about seismic source parameters. In particular, faulting style is taken into account with a theoretical corrective coefficient applied to the attenuation law. The validity of this correction is assessed through a comparison with observed data, attenuation law predictions corrected and not corrected, and the results of attenuation laws containing faulting style parameters. The probabilistic nature of the analysis is maintained, introducing into the classical hazard formulation a 2D probability density function describing the most probable focal mechanisms associated with each seismic source zone. This new expression may also be used in the framework of deaggregation analysis. Thus, the design earthquake resulting from the deaggregation is characterized by a focal mechanism. An application to a site located in the Southern Apennines, Italy, is shown. The result of the analysis emphasizes the importance of strike-slip events in the seismic hazard context, compared with normal faulting seismic activity in this region.
    Description: Published
    Description: 2124-2136
    Description: 4.2. TTC - Modelli per la stima della pericolosità sismica a scala nazionale
    Description: JCR Journal
    Description: restricted
    Keywords: Seismic hazard; Focal mechanism; Ground motion predictive equations ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 34
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    Earthquake forecasting and earthquake prediction: different approaches for obtaining the best model (2012)
    Seismological Society of America
    Details
    Publication Date: 2017-04-04
    Description: We consider the general problem of constructing or selecting the “best” earthquake forecast/prediction model. While many researchers have presented technical methods for solving this problem, the practical and philosophical dimensions are scarcely treated in the scientific literature, and we wish to emphasize these aspects here. Of particular interest are the marked differ- ences between approaches used to build long-term earthquake rupture forecasts and those used to conduct systematic earth- quake predictability experiments. Our aim is to clarify the dif- ferent approaches, and we suggest that these differences, while perhaps not intuitive, are understandable and appropriate for their specific goals. We note that what constitutes the “best” model is not uniquely defined, and the definition often depends on the needs and goals of the model’s consumer.
    Description: Published
    Description: 442-448
    Description: 4.2. TTC - Modelli per la stima della pericolosità sismica a scala nazionale
    Description: JCR Journal
    Description: reserved
    Keywords: model selection ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk
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  • 35
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    Narrow-band, transient signals in Central Apennines, Italy: hints for underground fluid migration? (2012)
    Wiley
    Details
    Publication Date: 2017-04-04
    Description: In this paper we investigate nature and properties of narrow-band, transient seismic signals observed by a temporary array deployed in the Val Tiberina area (central Apennines, Italy). These signals are characterized by spindle-shaped, harmonic waveforms with no clear S-wave arrivals. The first portion of the seismograms exhibits a main frequency peak centred at 4.5 Hz, while the spectrum of the slowly decaying coda is peaked at about 2 Hz. Events discrimination is performed using a matched-filtering technique, resulting in a set of 2466 detections spanning the 2010 January–March time interval. From a plane-wave-fitting procedure, we estimate the kinematic properties of signals pertaining to a cluster of similar events. The repetition of measurements over a large number of precisely aligned seismograms allows for obtaining a robust statistics of horizontal slownesses and propagation azimuths associated with the early portion of the waveforms. The P-wave arrival exhibits horizontal slownesses around 0.1 s km−1, thus suggesting waves impinging at the array almost vertically. Separately, we use traveltimes measured at a sparse network to derive independent constraints on epicentral location. Ray parameters and azimuths are calibrated using slowness measurements from a local, well-located earthquake. After this correction, the joint solution from traveltime inversion and array analysis indicates a source region spanning the 1–3 km depth interval. Considerations related to the source depth and energy, and the occurrence rate which is not related to the daily and weekly working cycles, play against a surface, artificial source. Instead, the close resemblance of these signals to those commonly observed in volcanic environments suggest a source mechanism related to the resonance of a fluid–filled fracture, likely associated with instabilities in the flux of pressurized CO2.
    Description: Published
    Description: 918-928
    Description: 1.1. TTC - Monitoraggio sismico del territorio nazionale
    Description: JCR Journal
    Description: reserved
    Keywords: Fracture and flow ; Earthquake source observations ; Interface waves ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
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  • 36
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    Modeling repeated slip failures on faults governed by slip-weakening friction (2012)
    Seismological Society of America
    Details
    Publication Date: 2017-04-03
    Description: The single-body mass-spring analog model has been largely used to simulate the recurrence of earthquakes on faults described by rate- and state-dependent rheology. In this paper, the fault was assumed to be governed by the classical slip-weakening (SW) law in which the frictional resistance linearly decreases as the developed slip increases. First, a closed-form fully analytical solution to the 1D elastodynamic problem was derived, expressing the time evolution of the slip and its time derivative. Second, a suitable mechanism for the recovery of stress during the interseismic stage of the rupture was proposed, and this stress recovery was shown quantitatively to make possible the simulation of repeated instabilities with the SW law. Moreover, the theoretical predictions were shown to be compatible with the numerical solutions obtained by adopting a rate and state constitutive model. The analytical solution developed here is, by definition, dynamically consistent and nonsingular. Moreover, the slip velocity function within the coseismic time window found here can be easily incorporated into slip inversion algorithms.
    Description: Published
    Description: 812-821
    Description: 3.1. Fisica dei terremoti
    Description: JCR Journal
    Description: restricted
    Keywords: Earthquake recourrence ; Source time function ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 37
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    Investigating Rupture Direction for Three 2012 Moderate Earthquakes in Northern Italy from Inversion of Peak Ground-Motion Parameters (2012)
    Seismological Society of America
    Details
    Publication Date: 2017-04-04
    Description: We investigate the possibility of inferring the dominant horizontalrupture direction for moderate earthquakes from the inversion of peak ground-motion parameters. To this aim, we adopt a technique that was devised and applied to large earthquakes for retrieving both the dominant rupture direction and the surface fault projection to be used with a proper distance metric to refine the ShakeMap computation. In the present paper, the procedure was applied to three moderate earthquakes that occurred in 2012 in Northern Italy three days apart: the M 4.2 Pre-Alpi Venete earthquake on 24 January, the M 4.9 Reggio Emilia earthquake on 25 January, and the M 5.4 Parma earthquake on 27 January. For two of the three analyzed events, the technique identifies a dominant horizontal-rupture direction, which is consistent with the strike directions inferred from the focal mechanisms. For theM 5.4 event, which is a deep (about 61 km) thrust-faulting mechanism earthquake, the inferred dominant rupture direction allows identification of the northeast-dipping plane as the fault plane in accordance with the aftershocks distribution.
    Description: Published
    Description: 2764–2770
    Description: 4.1. Metodologie sismologiche per l'ingegneria sismica
    Description: JCR Journal
    Description: restricted
    Keywords: Fault directivity ; Peak Ground-Motion Parameters ; 04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution
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  • 38
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    From Induced Seismicity to Direct Time-Dependent Seismic Hazard (2012)
    Seismological Society of America
    Details
    Publication Date: 2017-04-04
    Description: The growing installation of industrial facilities for subsurface exploration worldwide requires continuous refinements in understanding both the mechanisms by which seismicity is induced by field operations and the related seismic hazard. Particularly in proximity of densely populated areas, induced low-to-moderate magnitude seismicity characterized by high-frequency content can be clearly felt by the surrounding inhabitants and, in some cases, may produce damage. In this respect we propose a technique for time-dependent probabilistic seismic-hazard analysis to be used in geothermal fields as a monitoring tool for the effects of on-going field operations. The technique integrates the observed features of the seismicity induced by fluid injection and extraction with a local ground-motion prediction equation. The result of the analysis is the time-evolving probability of exceedance of peak ground acceleration (PGA), which can be compared with selected critical values to manage field operations. To evaluate the reliability of the proposed technique, we applied it to data collected in The Geysers geothermal field in northern California between 1 September 2007 and 15 November 2010. We show that the period considered the seismic hazard at The Geysers was variable in time and space, which is a consequence of the field operations and the variation of both seismicity rate and b-value.We conclude that, for the exposure period taken into account (i.e., two months), as a conservative limit, PGA values corresponding to the lowest probability of exceedance (e.g., 30%) must not be exceeded to ensure safe field operations. We suggest testing the proposed technique at other geothermal areas or in regions where seismicity is induced, for example, by hydrocarbon exploitation or carbon dioxide storage.
    Description: Published
    Description: 2563–2573
    Description: 4.1. Metodologie sismologiche per l'ingegneria sismica
    Description: JCR Journal
    Description: restricted
    Keywords: Seismic hazard ; Induced seismicity ; Non-homogeneous poisson model ; The Gysers geothermal area ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 39
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    Seismic Hazard Assessment (2003–2009) for the Italian Building Code (2012)
    Seismological Society of America
    Details
    Publication Date: 2017-04-04
    Description: This paper describes the probabilistic assessment of seismic hazard (PSHA) of Italy in view of the building codes from 2003 to 2009. A code was issued in 2003 as Prime Minister Ordinance, requiring that a PSHA for updating the seismic zoning would be performed in one year, in terms of horizontal peak ground acceleration (PGA) with 10% probability of exceedance in 50 years, on hard ground. For the first time in Italy a working group, established by Istituto Nazionale di Geofisica e Vulcanologia (INGV), adopted a logic-tree approach to model the epistemic uncertainty in: the completeness of the earthquake catalog, the assessment of the seismicity rates and Mmax, and the ground motion prediction equations. The seismic hazard has been computed over a grid of more than 16,000 points for the median value (50th percentile), 84th and 16th percentiles of the 16 branches of the logic tree. Using the same input model, PGA values and spectral accelerations for 10 spectral periods were computed for 9 different probabilities of exceedance in 50 years. This wealth of data made it possible to base the design spectra of a new building code on point hazard data instead of being related to just four zones. The 2009, Mw 6.3 L’Aquila earthquake has led many to attempt to test the reliability of this study. In this paper we analyze suggestions coming from that event and conclude that significant changes to the design spectra are not be recommended based just on evidence from the L’Aquila earthquake.
    Description: Published
    Description: 1885–1911
    Description: 4.2. TTC - Modelli per la stima della pericolosità sismica a scala nazionale
    Description: JCR Journal
    Description: restricted
    Keywords: seismic hazard ; italy ; building code ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk
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  • 40
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    Seismic Network Evaluation through Simulation: An Application to the Italian National Seismic Network (2011)
    Seismological Society of America
    Details
    Publication Date: 2017-04-04
    Description: A properly organized seismic network is a valuable tool for monitoring seismic zones and assessing seismic hazards. In this paper we propose a new method (seismic network evaluation through simulation, SNES) to evaluate the performance of hypocenter location of a seismic network. The SNES method gives, as a function of magnitude, hypocentral depth, and confidence level, the spatial distribution of the number of active stations in the location procedure and their relative azimuthal gaps, along with confidence intervals in hypocentral parameters. The application of the SNES method also permits evaluation of the magnitude of completeness (MC), the background noise levels at the stations, and assessment of the appropriateness of the velocity model used in location routine. Italy sits on a tectonically active plate boundary at the convergence of the Eurasian and African lithospheric plates and has a high level of seismicity. In this paper, we apply the SNES method to the Italian National Seismic Network (Rete Sismica Nazionale Centralizzata dell’Istituto Nazionale di Geofisica e Vulcanologia, RSNC– INGV) which has monitored Italian seismicity since the early 1980s, following the destructive 1980 Irpinia earthquake. In recent years, the RSNC–INGV has grown significantly. In fact, in February 2010, it received signals from 305 seismic stations, 258 with wideband three-component sensors. We constructed SNES maps for magnitudes of 1.5, 2, 2.5, and 3, fixing the hypocentral depth at 10 km and the confidence level at 95%. Through the application of the SNES method, we show that the RSNC–INGV provides the best monitoring coverage in the Apennine Mountains with errors that for M 2, are less than 2 and 4 km for epicenter and hypocentral depth, respectively. At M 2.5 this seismic network is capable of constraining earthquake hypocenters to depths of about 150 km for most of the Italian Peninsula. This seismic network provides a threshold of completeness down to M 2 for almost the entire Italian territory.
    Description: Published
    Description: 1213-1232
    Description: 2.5. Laboratorio per lo sviluppo di sistemi di rilevamento sottomarini
    Description: JCR Journal
    Description: reserved
    Keywords: Italian National Seismic Network ; Magnitude of Completeness ; Location Performance ; Seismic Noise ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
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  • 41
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    Developing Seismogenic Source Models Based on Geologic Fault Data (2011)
    Seismological Society of America
    Details
    Publication Date: 2017-04-04
    Description: Calculating seismic hazard usually requires input that includes seismicity associated with known faults, historical earthquake catalogs, geodesy, and models of ground shaking. This paper will address the input generally derived from geologic studies that augment the short historical catalog to predict ground shaking at time scales of tens, hundreds, or thousands of years (e.g., SSHAC 1997). A seismogenic source model, terminology we adopt here for a fault source model, includes explicit three-dimensional faults deemed capable of generating ground motions of engineering significance within a specified time frame of interest. In tectonically active regions of the world, such as near plate boundaries, multiple seismic cycles span a few hundred to a few thousand years. In contrast, in less active regions hundreds of kilometers from the nearest plate boundary, seismic cycles generally are thousands to tens of thousands of years long. Therefore, one should include sources having both longer recurrence intervals and possibly older times of most recent rupture in less active regions of the world rather than restricting the model to include only Holocene faults (i.e., those with evidence of large-magnitude earthquakes in the past 11,500 years) as is the practice in tectonically active regions with high deformation rates. During the past 15 years, our institutions independently developed databases to characterize seismogenic sources based on geologic data at a national scale. Our goal here is to compare the content of these two publicly available seismogenic source models compiled for the primary purpose of supporting seismic hazard calculations by the Istituto Nazionale di Geofisica e Vulcanologia (INGV) and the U.S. Geological Survey (USGS); hereinafter we refer to the two seismogenic source models as INGV and USGS, respectively. This comparison is timely because new initiatives are emerging to characterize seismogenic sources at the continental scale (e.g., SHARE in the Euro- Mediterranean, http://www.share-eu.org/; EMME in the Middle East, http://www.emmegem. org/) and global scale (e.g., GEM, http://www.globalquakemodel.org/; Anonymous 2008). To some extent, each of these efforts is still trying to resolve the level of optimal detail required for this type of compilation. The comparison we provide defines a common standard for consideration by the international community for future regional and global seismogenic source models by identifying the necessary parameters that capture the essence of geological fault data in order to characterize seismogenic sources. In addition, we inform potential users of differences in our usage of common geological/seismological terms to avoid inappropriate use of the data in our models and provide guidance to convert the data from one model to the other (for detailed instructions, see the electronic supplement to this article). Applying our recommendations will permit probabilistic seismic hazard assessment codes to run seamlessly using either seismogenic source input. The USGS and INGV database schema compare well at a first-level inspection. Both databases contain a set of fields representing generalized fault three-dimensional geometry and additional fields that capture the essence of past earthquake occurrences. Nevertheless, there are important differences. When we further analyze supposedly comparable fields, many are defined differently. These differences would cause anomalous results in hazard prediction if one assumes the values are similarly defined. The data, however, can be made fully compatible using simple transformations.
    Description: USGS Senior Scientist In Residence
    Description: Published
    Description: 519-525
    Description: 3.2. Tettonica attiva
    Description: 4.1. Metodologie sismologiche per l'ingegneria sismica
    Description: 4.2. TTC - Modelli per la stima della pericolosità sismica a scala nazionale
    Description: JCR Journal
    Description: open
    Keywords: Active fault ; fault source ; database ; seismic hazard ; Italy ; USA ; 04. Solid Earth::04.04. Geology::04.04.01. Earthquake geology and paleoseismology ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk ; 04. Solid Earth::04.07. Tectonophysics::04.07.04. Plate boundaries, motion, and tectonics ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
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  • 42
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    Tsunami early warning using earthquake rupture duration and P-wave dominant-period: the importance of length and depth of faulting (2011)
    Wiley
    Details
    Publication Date: 2017-04-03
    Description: After an earthquake, rapid, real-time assessment of hazards such as ground shaking and tsunami potential is important for early warning and emergency response. Tsunami potential depends on sea floor displacement, which is related to the length, L, width, W, mean slip, D, and depth, z, of earthquake rupture. Currently, the primary discriminant for tsunami potential is the centroid-moment tensor magnitude, MwCMT, representing the seismic potency LWD, and estimated through an indirect, inversion procedure. The obtained MwCMT and the implied LWD value vary with the depth of faulting, assumed earth model and other factors, and is only available 30 min or more after an earthquake. The use of more direct procedures for hazard assessment, when available, could avoid these problems and aid in effective early warning. Here we present a direct procedure for rapid assessment of earthquake tsunami potential using two, simple measures on P-wave seismograms – the dominant period on the velocity records, Td, and the likelihood that the high-frequency, apparent rupture-duration, T0, exceeds 50-55 sec. T0 can be related to the critical parameters L and z, while Td may be related to W, D or z. For a set of recent, large earthquakes, we show that the period-duration product TdT0 gives more information on tsunami impact and size than MwCMT and other currently used discriminants. All discriminants have difficulty in assessing the tsunami potential for oceanic strike-slip and back-arc or upper-plate, intraplate earthquake types. Our analysis and results suggest that tsunami potential is not directly related to the potency LWD from the “seismic” faulting model, as is assumed with the use of the MwCMT discriminant. Instead, knowledge of rupture length, L, and depth, z, alone can constrain well the tsunami potential of an earthquake, with explicit determination of fault width, W, and slip, D, being of secondary importance. With available real-time seismogram data, rapid calculation of the direct, period- duration discriminant can be completed within 6-10 min after an earthquake occurs and thus can aid in effective and reliable tsunami early warning.
    Description: In press
    Description: 1.1. TTC - Monitoraggio sismico del territorio nazionale
    Description: JCR Journal
    Description: open
    Keywords: Earthquake dynamics ; Earthquake source observations ; Seismic monitoring ; Body waves ; Early warning ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
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  • 43
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    Multiplet Focal Mechanisms from Polarities and Relative Locations: The Iznajar Swarm in Southern Spain (2010)
    Seismological Society of America
    Details
    Publication Date: 2017-04-04
    Description: In April 1998, a swarm of 1800 microearthquakes near the village of Iznajar (southern Spain) was recorded at the Granada basin short-period seismic network. Focal mechanisms from local P-wave polarities are poorly constrained and cannot characterize the seismotectonics of the series. Here we combine polarity information and multiplet relocation to address this issue. We use waveform cross correlation on P and S arrivals to identify events with highly similar seismograms, group our detections into multiplet clusters, and invert the cross-correlation time delays to obtain precise relative locations. Relative locations have errors of several tens to a few hundreds of meters horizontally and vertically, and define strike and dip of active fault patches with an accuracy of 20°–30°. We introduce the multiplet fault plane orientations into focal mechanism inversion, now yielding mostly well-constrained solutions, in addition to resolving the nodal plane symmetry. We observe mainly north-south left-lateral strike-slip faulting and a few north-northwest–south-southeast normal faulting solutions, illustrating the kinematic complexity of the swarm, and pointing to a local deformation style different from the nearby Granada basin.
    Description: Published
    Description: 3421-3429
    Description: 3.1. Fisica dei terremoti
    Description: JCR Journal
    Description: reserved
    Keywords: Fault plane solution ; Precise location ; Seismic swarm ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 44
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    On the Stability and Reproducibility of the Horizontal-to-Vertical Spectral Ratios on Ambient Noise: Case Study of Cavola, Northern Italy (2010)
    Seismological Society of America
    Details
    Publication Date: 2017-04-04
    Description: Horizontal-to-vertical spectral ratios using ambient noise (HVNSR) are commonly used in site effects studies. In the practice, many operators assume stability over time of HVNSR and base their analyses on few very short time windows. The availability of a long period of continuous microtremor recording allowed us to analyze three months of data coming from a dense array experiment performed at Cavola, a village in northern Apennines. This condition offers a good opportunity to check the validity of the stability assumption and to investigate variations of the local ambient noise wave-field composition. The Cavola site is characterized by landslide sediments over stiffer materials with a moderate impedance contrast and by a complex morphology. An intense industrial activity in the village contributes to the generation of seismic noise. After identifying this noise source in the time series, we evaluate its effects on HVNSR. The results indicate that the spectral peak of HVNSR varies in amplitude and frequency, posing a warning about stability in time. Analyzing the spectra we identify the anthropic activity as responsible for changes in the composition of the noise wave field. These variations affect HVNSR, including peak frequency and also ground-motion polarization.
    Description: Published
    Description: 1263-1275
    Description: 4.1. Metodologie sismologiche per l'ingegneria sismica
    Description: JCR Journal
    Description: restricted
    Keywords: noise measurements ; Rayleigh waves ; polarization ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis
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  • 45
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    Importance of Mapping Design Earthquakes: Insights for the Southern Apennines, Italy (2009)
    Seismological Society of America
    Details
    Publication Date: 2021-06-21
    Description: Probabilistic seismic hazard analysis is currently the soundest basis for the rational evaluation of ground-motion hazard for site-specific engineering design and assessment purposes. An increasing number of building codes worldwide acknowledge the uniform hazard spectra as the reference to determine design actions on structures and to select input ground motions for seismic structural analysis. This is the case, for example, in Italy where the new seismic code also requires the seismic input for nonlinear dynamic analysis to be selected on the basis of dominating events, for example, identified via disaggregation of seismic hazard. In the present study, the design earthquakes expressed in terms of representative magnitude (M), distance (R), and ε were investigated for a wide region in the southern Apennines, Italy. To this aim, the hazards corresponding to peak ground acceleration and spectral acceleration at 1 sec with a return period of 475 yr were disaggregated. For each of the disaggregation variables the shape of the joint and marginal probability density functions were studied. The first two modes expressed by M, R, and ε were extracted and mapped for the study area. The results shown provide additional information, in terms of source and ground-motion parameters, to be used along with the standard hazard maps to better select the design earthquakes. The analyses also allow us to assess how various frequency ranges of the design spectrum are differently contributed by seismic sources in the study area.
    Description: Published
    Description: 2979–2991
    Description: 4.2. TTC - Modelli per la stima della pericolosità sismica a scala nazionale
    Description: JCR Journal
    Description: reserved
    Keywords: seismic hazard ; disaggregation ; Southern Apenniens ; design earthquake ; 04. Solid Earth::04.06. Seismology::04.06.04. Ground motion ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 46
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    Using WiMAX to improve volcano monitoring during an emergency: a feasibility study of the WEIRD system applied to the Campi Flegrei volcanic area scenario (southern Italy) (2009)
    Seismological Society of America
    Details
    Publication Date: 2017-04-04
    Description: IEEE Standard for Local and Metropolitan Area Networks (hereafter IEEE 802.16; online at http://standards.ieee.org/getieee802/802.16.html) is one of the most promising mobile and fixed broadband wireless access technologies for next-generation all-IP networks in the 3.5 GHz band (European spectrum profile). Commonly known as Universal WiMAX (worldwide inter-operability for microwave access), this access technology reaches a high bit rate and covers large areas with a single base station, making it possible to offer connectivity to end users in a cost-effective way. A further useful property of the WiMAX technology is that the transmission can be used both in line-of-sight (LOS) and non-line-of-sight (NLOS) environments, allowing highly feasible communications (WiMAX Forum 2004). Thanks to these features, IEEE 802.16 opens the way to the use of wireless technologies in the environmental monitoring of areas such as seismic and volcanic zones.
    Description: European Community’s Sixth Framework Programme, Contract no. IST-034622-IP
    Description: Published
    Description: 411-419
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: WiMAX ; volcano monitoring ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
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  • 47
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    The Paganica Fault and surface coseismic ruptures caused by the 6 april 2009 earthquake (L’Aquila, central Italy) (2009)
    Seismological Society of America
    Details
    Publication Date: 2022-06-14
    Description: On 6 April 2009, at 01:32 GMT, an Mw 6.3 seismic event hit the central Apennines, severely damaging the town of L’Aquila and dozens of neighboring villages and resulting in approximately 300 casualties (Istituto Nazionale di Geofisica e Vulcanologia, http://www.ingv.it; MedNet, http://mednet.rm.ingv.it/proce- dure/events/QRCMT/090406_013322/qrcmt.html). This earth- quake was the strongest in central Italy since the devastating 1915 Fucino event (Mw 7.0). The INGV national seismic net- work located the hypocenter 5 km southwest of L’Aquila, 8–9 km deep. Based on this information and on the seismotectonic framework of the region, earthquake geologists traveled to the field to identify possible surface faulting (Emergeo Working Group 2009a, 2009b). The most convincing evidence of pri- mary surface rupture is along the Paganica fault, the geometry of which is consistent with seismological, synthetic aperture radar (SAR) and GPS data. Investigation of other known nor- mal faults of the area, i.e., the Mt. Pettino, Mt. San Franco, and Mt. Stabiata normal faults suggested that these structures were not activated during the April 6 shock (Emergeo Working Group 2009a, 2009b). In this report, we first describe the seismotectonic frame- work of the area, and then we present the field information that supports the occurrence of surficial displacement on the Paganica fault.
    Description: Published
    Description: 940-950
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: open
    Keywords: Surface coseismic ruptures ; Paganica Fault ; earthquake ; 04. Solid Earth::04.04. Geology::04.04.01. Earthquake geology and paleoseismology ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 48
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    Characteristics of Ambient Noise Cross-Correlations in Northern Italy within the 0.1- to 0.6-Hz Frequency Range (2008)
    Seismological Society of America
    Details
    Publication Date: 2017-04-04
    Description: In this note, we investigate the characteristics of ambient noise cross-correlations for station pairs in northern Italy, considering the secondary microseism bandwidth (0.1-0.6 Hz). The preliminary analysis that we performed exploiting the available continuous recording in the investigated area, agrees with the recent results of Pedersen et al. (2007): the directionality of the noise signal cannot be disregarded when the group velocity is estimated in the range 0.1-0.6 Hz and the selection of the path orientation for tomography must be carefully performed. In particular, while the favourable directions with respect to microseisms generated along the Atlantic coasts of France, Norway and British Islands cover a quite wide azimuthal range (from about 270N to 5N), allowing us to reliably estimate the fundamental mode Rayleigh group velocity for paths in the Alps (about 2.7 km/s), more care must be taken when the microseisms are generated in the Mediterranean Sea. In that case, different locations of the generating areas of microseisms could provide biased estimates of the group velocity due to differences between the true and the apparent velocity of propagation between the stations.
    Description: Published
    Description: 1389-1398
    Description: 1.1. TTC - Monitoraggio sismico del territorio nazionale
    Description: JCR Journal
    Description: reserved
    Keywords: microseisms ; ambient noise ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
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  • 49
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    SASHA: A Computer Program to Assess Seismic Hazard from Intensity Data (2008)
    Seismological Society of America
    Details
    Publication Date: 2017-04-04
    Description: The evaluation of seismic hazard over wide territories is a basic tool for planning activities aimed at earthquake damage mitigation. This is commonly performed through probabilistic approaches based on the statistical analysis of past seismicity. Among these, due to its wide application worldwide, the Cornell-McGuire approach (Cornell 1968; McGuire 1978) has become a kind of “standard” methodology for probabilistic seismic hazard assessment (PSHA). In Italy, several national seismic hazard maps were produced in recent years (Slejko et al. 1998; Albarello et al. 2000; MPS Working Group 2004) by following this procedure as implemented by Bender and Perkins (1987). Yet despite its widespread application, this standard methodology presents severe drawbacks due to its strong sensitivity to some ill-defined aspects, such as geometry of seismic sources, attenuation of ground motion with distance from the source, completeness of available seismic catalogs, etc. Moreover, this kind of approach does not allow the full exploitation of a large amount of documentary data available at the site about the seismic effects of past earthquakes (Albarello and Mucciarelli 2003). Another drawback is that the standard approach was developed with the assumption that the seismicity database used to feed the computational model is constituted by instrumental data (magnitude, epicentral locations, etc.). However, in many countries (first and foremost, Italy) the bulk of the seismic database is constituted by macroseismic data, and thus the application of the standard method requires a “forcing” of macroseismic information into a para-instrumental format. But macroseismic information is not isomorphic to instrumental data since intensity values are discrete, ordinal, and range-limited. This implies that, in principle, mathematical formalizations suitable to instrumental information cannot be used to manage macroseismic data (see, e.g., Pasolini et al. 2008a, 2008b). To overcome some of these difficulties and to better exploit available information, probabilistic hazard evaluations based on observed intensity data were performed in Europe (Monachesi et al. 1994; Papoulia and Slejko 1997; Azzaro et al. 1999; Albarello et al. 2002) and Japan (Bozkurt et al. 2007) using alternative numerical procedures. An apparent limitation of these studies is the fact that PSH estimates are provided in terms of intensity, and this conflicts with the fact that ground acceleration still remains the traditional output of PSHA devoted to seismic design. However, a new interest has recently grown around macroseismic intensity. In fact, when damage scenarios and post-earthquake emergency planning are of concern, hazard assessment in terms of intensity as ground-shaking measure may be more suitable than conventional estimates based on instrumental parameters (PGA, etc.). A further possible advantage of these kinds of approaches is that they provide hazard evaluations completely independent from the standard ones and more directly linked to empirical observations (local seismic history). Thus, they could represent a useful benchmark for a direct assessment of reliability of traditional PSH estimates (Mucciarelli et al. 2000, 2006, 2008; Bozkurt et al. 2007). In this paper we present the computer program SASHA (Site Approach to Seismic Hazard Assessment), which implements the intensity-based PSHA procedure originally proposed by Magri et al. (1994) and then improved by Albarello and Mucciarelli (2002). It relies on the analysis of the site seismic history, i.e., the dataset of seismic effects (macroseismic intensities) documented during past earthquakes at a given locality. This methodology (hereafter, site approach) has been specifically developed to handle macroseismic data, and thus both the peculiar nature of intensity values (discrete, ordinal, range-limited) and relevant uncertainty (ill-defined intensity values, completeness of site seismic history, etc.) are taken into account by a coherent statistical approach that does not require any assumption about earthquake recurrence model and seismic source geometry. Furthermore, no aftershock removal is required in advance and epicentral data are only considered to integrate (when necessary) felt data at the site. Several PSHA studies have been performed in the last decade in Italy using different versions of the site approach (Mucciarelli et al. 2000; Albarello et al. 2002; D’Amico and Albarello 2003; Albarello, Azzaro et al. 2007; Azzaro et al. 2008). SASHA’s theoretical background is briefly outlined in the next section of the paper. Then, we describe the most important features of SASHA along with a sample application to the Italian area.
    Description: Published
    Description: 663-671
    Description: 4.2. TTC - Scenari e mappe di pericolosità sismica
    Description: JCR Journal
    Description: reserved
    Keywords: computational code ; probabilistic seismic hazard assessment ; intensity data ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk ; 05. General::05.01. Computational geophysics::05.01.05. Algorithms and implementation
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  • 50
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    A comparison of sea floor and on land seismic ambient noise in the Campi Flegrei caldera (Southern Italy) (2008)
    Seismological Society of America
    Details
    Publication Date: 2017-04-04
    Description: The Campi Flegrei (southern Italy) is one of the most active calderas in the world. This caldera is characterized by episodes of slow vertical ground movement, called bradyseism. With several hundred thousand people living within its borders, this area is in a high-risk category should there be an eruption. The seismological monitoring system in the Campi Flegrei is based on nine seismic stations, eight of which are equipped with short-period seismometers (1 Hz), and one with a broadband seismometer (60 sec–50 Hz). While all of the seismic stations are located on land, part of the seismic activity occurs in the undersea area of the Pozzuoli Gulf (Campi Flegrei), where there are no seismic stations. This gap in the data coverage produces a biased and incomplete image of the volcanic area.We carried out an experiment in the Pozzuoli Gulf with the installation of two broadband seismic stations on the seafloor with remote and continuous data acquisition for a duration of 31 days between January and March 2005. Using the data acquired, we have computed the power spectral density (PSD) to characterize the background seismic noise, and to evaluate the true noise variation, we have generated the seismic noise probability density functions from the computed PSD curves. The results of our analysis show that the broadband seismic noise is high when compared with the Peterson noise model (land model), but for periods less than 0.3 sec, the seismic noise on the seafloor is lower than the recordings on land over the same period range. The last bradyseismic crisis (1982–1984) highlights the importance of this frequency range, where most of the spectral content of the recorded earthquakes was observed. Finally, we evaluate the detection threshold of a new seismic station located on the seafloor of the Campi Flegrei caldera considering the characteristics of the local seismicity. This analysis shows that the detection threshold for the sea-floor stations (Mw ∼ 0:2) is less than that for land stations (Mw ∼ 0:8).
    Description: Published
    Description: 2962–2974
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Campi Flegrei Caldera ; Sea-Floor and On-Land Seismic ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
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  • 51
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    A WebGIS Application for Rendering Seismic Hazard Data in Italy (2008)
    Seismological Society of America
    Details
    Publication Date: 2017-04-04
    Description: In 2004, on behalf of the Department of Civil Protection (DPC—Dipartimento della Protezione Civile), the Istituto Nazionale di Geofisica e Vulcanologia (INGV) released a new Italian seismic hazard map. The entire scientific process was public and transparent: an international panel of experts conducted a peer review while the work was in progress, and all the input data, the final output, and the technical documentation was published. The details of the entire process are available on a dedicated Web site (http://zonesismiche.mi.ingv.it). Following the publication of the reference map, the DPC financed the S1 project to produce a set of additional elaborations that would better describe the Italian seismic hazard. This resulted in a set of maps expressed in terms of PGA and Sa (spectral accelerations), both evaluated for different probabilities of exceedance. Finally, the overall information, more than a “set of maps,” can be considered the realization of what can be defined as a complete seismic hazard model. One of the aims of the S1 project is the dissemination of the data through the Web (http://esse1.mi.ingv.it). To evaluate the state of the art in disseminating this type of data we conducted an overview of the Web sites of earthquake-prone countries,and in several cases we experienced difficulties and slowness in finding seismic hazard information for a specific area. Our goal was to provide a tool with a combined high level of interactivity and ease of use. Recognizing the need for a Web application that would enable users to intuitively and interactively locate the area of interest and show pertinent data in various formats, we decided to develop a dedicated Web interface.
    Description: Published
    Description: 68-78
    Description: 4.2. TTC - Scenari e mappe di pericolosità sismica
    Description: 5.4. TTC - Sistema Informativo Territoriale
    Description: 5.9. TTC - Sistema web
    Description: JCR Journal
    Description: reserved
    Keywords: WebGIS ; italy ; seismic hazard ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk ; 05. General::05.02. Data dissemination::05.02.02. Seismological data
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  • 52
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    Comparison of Probabilistic Seismic Hazard Estimates in Italy (2008)
    Seismological Society of America
    Details
    Publication Date: 2017-04-04
    Description: Macroseismic intensity has recently attracted attention as a tool for validating probabilistic seismic hazard assessment (PSHA) studies or as an alternative method for PSHA in countries where the historical catalog is much longer than the instrumental one. In Italy, the new seismic hazard map was recently produced using the Cornell–McGuire approach in terms of the peak ground acceleration characterized by a 10% exceedance probability for an exposure time of 50 yr (Amax). We compare this map with an alternative one, produced using a different approach based on a nonparametric and zonation-free statistical analysis of local seismic histories. In this case, results are expressed in terms of the maximum intensity corresponding to an exceedance probability of not less than 10% for an exposure time of 50 yr (Iref ). In order to compare the two maps, we selected 1401 control sites, where local seismic history includes at least 10 intensity values relative to felt effects documented during past earthquakes. The values of Amax and Iref at these sites have been ranked in the respective domains. The spatial distribution of rank differences of Amax and Iref values shows a strong correlation with the seismogenic zoning used in the calculation of PSHA following the Cornell–McGuire approach. This suggests that the adopted zoning could be incomplete (some further “hidden” sources may exist) and too rough to capture actual seismogenic sources. Because more detailed zoning is prevented by the amount of data available, the results obtained suggest the preference of zonation-free approaches for seismic hazard assessment in Italy. Furthermore, among the possible zonation-free approaches, those that offer better exploitation of local information about the effects of past earthquakes would be preferred.
    Description: Published
    Description: 2652–2664
    Description: 4.2. TTC - Scenari e mappe di pericolosità sismica
    Description: JCR Journal
    Description: reserved
    Keywords: probabilistic seismic hazard estimates ; statistical analysis ; Italy ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk ; 05. General::05.01. Computational geophysics::05.01.04. Statistical analysis
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  • 53
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    Real-time evolutionary earthquake location for seismic early warning (2008)
    Seismological Society of America
    Details
    Publication Date: 2017-04-04
    Description: An effective early-warning system must provide probabilistic estimates of the location and size of a potentially destructive earthquake within a few seconds after the event is first detected. In this work we present an evolutionary, real-time location technique based on an equal differential time (EDT) formulation and a probabilistic approach for describing the hypocenter estimation. The algorithm, at each timestep, relies on the information from triggered arrivals and not-yet-triggered stations. With just one recorded arrival, the hypocentral location is constrained by the Voronoi cell around the first triggering station constructed using the travel times to the not-yet-triggered stations.With two or more triggered arrivals, the location is constrained by the intersection of the volume defined by the Voronoi cells for the remaining, not-yet-triggered stations and the EDT surfaces between all pairs of triggered arrivals. As time passes and more triggers become available, the evolutionary location converges to a standard EDT location. Synthetic tests performed using the geometry of the Irpinia seismic network, southern Italy (ISNet), and the simulation of an evolutionary location for the 2000 Mw 6:6 Western Tottori, Japan, earthquake indicate that when a dense seismic network is available, reliable location estimates suitable for early-warning applications can be achieved after 1–3 sec from the first event detection. A further simulation with an Mw 6:7 southern Greece earthquake shows that at a regional scale, the real-time location can provide useful constraints on the earthquake position several seconds before a non-real-time algorithm. Finally, we show that the robustness of the algorithm in the presence of outliers can be effectively used to associate phase arrivals coming from events occurring close in time, and we present a preliminary algorithm for event detection.
    Description: Published
    Description: 1482–1494
    Description: 4.1. Metodologie sismologiche per l'ingegneria sismica
    Description: JCR Journal
    Description: reserved
    Keywords: Early warning ; earthquake location ; 04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution
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  • 54
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    Comment on "Influence of fochal mechanism in probabilistic seismic hazard analysis" by Vincenzo Convertito and Andre' Herrero (2007)
    Seismological Society of America
    In:  Convertito, V., and A. Herrero (2004). Influence of focal mechanism in probabilistic seismic hazard analysis, Bull. Seism. Soc. Am. 94, no. 6, 2124–2136.
    Details
    Publication Date: 2017-04-04
    Description: The influence of style-of-faulting on strong groundmotions has been the subject of debate for some time. Although some controversy persists, the general consensus is that ground motions produced by reverse faults are higher than those produced by normal faults, whereas motions from strike-slip faults are somewhere in between. In a recent article, Convertito and Herrero (2004) derived a correction factor for focal mechanism to be applied to predictive equations. This issue was previously addressed by Bommer et al. (2003). Although this article is cited by Convertito and Herrero, it seems that its aims and scope were not well understood, and we would therefore like to clarify what the method presented therein entails, especially because we feel that Convertito and Herrero’s approach of characterizing focal mechanisms based solely on the radiation pattern is difficult to justify. After presenting their correction scheme, Convertito and Herrero go on to present an implementation of probabilistic seismic hazard analysis (PSHA) explicitly accounting for focal mechanism. This represents a real innovation in terms of methodology because it allows propagation of the improvements in ground-motion prediction gained through the focal-mechanism adjustments to hazard estimation. Characterizing the dominant scenario in terms of focal mechanism furthermore has the advantage of providing constraints for numerical simulations that are derived directly from the hazard computation, rather than from arbitrary assumptions. However, in our opinion, the methodology presented by Convertito and Herrero has some serious shortcomings which would need to be addressed before it can lead to improvements of the PSHA methodology. Our discussion includes a comparison with the new Italian seismic hazard map, which was derived using the Bommer et al. (2003) adjustment methodology.
    Description: Published
    Description: 750-753
    Description: JCR Journal
    Description: reserved
    Keywords: strong ground-motions ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk
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  • 55
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    The Potential for Earthquake Early Warning in Italy Using ElarmS (2007)
    Seismological Society of America
    Details
    Publication Date: 2017-04-04
    Description: The new Italian National Seismic Network (INSN) is a dense network of broadband stations deployed for monitoring Italian seismicity. The network consists of 250 stations with a typical station spacing of !40 km. Earthquake early warning is the rapid detection of an event in progress, assessment of the hazard it poses, and transmission of a warning ahead of any significant ground motion. We explore the potential for using the INSN real-time network for the purpose of earthquake early warning. We run the ElarmS early warning methodology off-line using a data set of more than 200 events with magnitudes between 2.5 and 6.0. A scaling relation for magnitude determination from the dominant period of the first seconds of signal following the P onset is developed from the data set. The standard deviation in the magnitude estimates using this approach is 0.4 magnitude units, and all event magnitude estimates are within !0:75 magnitude units of the true magnitude. Given the existing distribution of seismic stations it takes an average of 10 sec after event initiation before the P wave has been detected at four stations. If we require a detection at four stations before issuing the first alert, then the blind zone, within which no warning would be available, has a radius of !37 km. The ElarmS methodology can provide a warning earlier than this but with a greater uncertainty. An assessment of past damaging earthquakes across Italy shows that applying ElarmS with the existing seismic network could provide warning to population centers in repeats of past events. For example, in a repeat of the 1980 Irpinia earthquake Naples could receive an !15- sec warning. The variations in the size of the blind zone and warning times for different regions can be used as a guide to selecting strategic locations for future station deployments.
    Description: Published
    Description: 495-503
    Description: 1.1. TTC - Monitoraggio sismico del territorio nazionale
    Description: JCR Journal
    Description: reserved
    Keywords: Early Warning ; Earthquake Location ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
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  • 56
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    An Improved Method for the Recognition of Seismic Families: Application to the Garfagnana-Lunigiana Area, Italy (2007)
    Seismological Society of America
    Details
    Publication Date: 2017-04-04
    Description: With the aim to find a more objective way to detect seismic families, we applied a series of successive steps to constrain the results of a waveform similarity analysis. The evaluation of similarity was carried out on the waveforms recorded in the period 1999–2003 by the stations operating in the Garfagnana area, located in northern Tuscany (Italy). The algorithm is based on the cross-correlation technique applied in a process that overcomes the limit of one order of magnitude between events to be compared through a bridging technique. In practice, if two couples of events (A, B) and (B, C), each exceeding the correlation threshold, share a common quake (B), then all three events are attributed to the same family even if the match between A and C is below a value chosen as a reference for similarity. To avoid any subjective choice of threshold for cross-correlation values, the results from the computation algorithm are submitted to a routine that gives increasing reliability to them if they are confirmed by the three components of the seismogram and if the number of families detected by each station is confirmed by more recordings. This latter constraint is made possible by the geometry of the recording network, with interdistances between stations of the order of 40–50 km. The process finally leads to the recognition of 27 families detected and confirmed by, on average, 3 stations that represent 40% of the recording capabilities. Since the performances of the recording network have been very odd in the past, especially in the early years of operation, the reliability of the detection is much higher, as in most cases the stations that detected the families were the only ones to be effectively recording. The methodology proved to be more efficient than other methods applied in the past; moreover, the results could be probably improved even more if, instead of doing a one-run process, it would be borne as a trial-and-error approach.
    Description: Published
    Description: 1903-1915
    Description: JCR Journal
    Description: reserved
    Keywords: Seismicity ; multiplets ; seismic families ; seismic sequences ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 57
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    Repeating Earthquakes as Low-Stress-Drop Events at a Border between Locked and Creeping Fault Patches (2005)
    Seismological Society of America
    Details
    Publication Date: 2017-04-04
    Description: The source of repeating earthquakes on creeping faults is modeled as a weak asperity at a border between much larger locked and creeping patches on the fault plane. The x^(-1/2) decrease in stress concentration with distance x from the boundaryis shown to lead directly to the observed scaling 〈T〉~〈M0〉^(1/6) between the average repeat time and average scalar moment for a repeating sequence. The stress drop in such small events at the border depends on the size of the large locked patch. For a circular patch of radius R and representative fault parameters, Dr = 7.6(m/R)3/5 MPa, which yields stress drops between 0.08 and 0.5 MPa (0.8–5 bars) for R between 2 km and 100 m. These low stress drops are consistent with estimates of stress drop for small earthquakes based on their seismic spectra. However, they are orders of magnitude smaller than stress drops calculated under the assumption that repeating sources are isolated stuck asperities on an otherwise creeping fault plane, whose seismic slips keep pace with the surrounding creep rate. Linear streaks of microearthquakes observed on creeping fault planes are trivially explained by the present model as alignments on the boundaries between locked and creeping patches.
    Description: NSF grants NSF-EAR-9902901 (CGS) and EAR-9805182 (JRR)
    Description: Published
    Description: 532-537
    Description: open
    Keywords: 04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article , article
    Format: 197949 bytes
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  • 58
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    Small-aperture Array for Seismic Monitoring of Mt.Vesuvius (2005)
    Seismological Society of America
    Details
    Publication Date: 2017-04-04
    Description: A small aperture quadripartite seismic array was installed on the south-east flanks of Mt. Vesuvius about 1 km far from the crater axis, in order to improve the seismic monitoring of this active volcano. The array has the following main purposes: i) to discriminate natural-source generated signals by artificial-source-generated signals; ii) to detect and track the source of possible Long Period (LP) events; iii) to detect coherent phases in the low frequency noise that may be related to magma movements (tremor insurgence). In addition, the array greatly helps in locating the seismic signals produced by blasts (both in land and sea), allowing a fast discrimination of possible natural long period (LP) quakes. The array is also an useful tool for retrieving the kinematic properties of the wavefield associated to volcano-tectonic (VT) earthquakes (more than 99% of the whole natural seismicity) and to all the other transients which are routinely observed(landslides, artificial blasts). We also use the array to investigate if correlated signals are present in the background noise (insurgence of volcanic tremor). The main result obtained during this first year of observation is that one LP was clearly recognized in the background seismicity at Mt. Vesuvius.
    Description: Published
    Description: 344-355
    Description: open
    Keywords: Volcano monitoring ; Array techniques ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 59
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    Automatic versus manual model differentiation to compute sensitivities and solve non-linear inverse problems (2002)
    3
    In:  Computers and Geosciences, Münster, 3, vol. 28, no. 45, pp. 309-326, pp. L11609, (ISBN 0-471-26610-8)
    Details
    Publication Date: 2002
    Keywords: Inversion ; Data analysis / ~ processing ; Non-linear effects ; Discrimination ; C&G
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    BIBLIOGRAPHY SEISMOLOGY
  • 60
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    The solution of linear equations by the conjugate gradient method (1967)
    Wiley
    In:  Mathematical Methods for Digital Computers, Volume 1, Sapporo, Japan, Wiley, vol. 17, no. 16, pp. 211-236, (ISBN 0080419208)
    Details
    Publication Date: 1967
    Keywords: Inversion
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    BIBLIOGRAPHY SEISMOLOGY
  • 61
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    Die Lösung linearer Gleichungen nach der Methode der konjugierten Gradienten (1967)
    Wiley
    In:  Mathematische Methoden für Digitalrechner, Sapporo, Japan, Wiley, vol. 1, no. 16, pp. 106-126, (ISBN 0080419208)
    Details
    Publication Date: 1967
    Keywords: Inversion
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    BIBLIOGRAPHY SEISMOLOGY
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