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  • Artikel  (36)
  • 04.06. Seismology  (36)
  • MDPI  (25)
  • Frontiers Media S.A.  (11)
  • American Chemical Society
  • American Institute of Physics (AIP)
  • 1
    Publikationsdatum: 2021-03-24
    Beschreibung: On October 27, 2017, an Mw 4 earthquake occurred close to the municipality of Montesano sulla Marcellana, less than 10 km external to the concession of the largest European onshore hydrocarbon reservoir—the Val d’Agri oilfield (Southern Italy). Being a weak event located outside the extended monitoring domain of the industrial concession, the relevance of this earthquake and the possible links with the hydrocarbon exploitation were not extensively discussed. Actually, the analysis of shallow seismic events close to subsurface exploitation domains plays a significant role in the definition of key parameters in order to discriminate between natural, triggered, and induced seismicity, especially in tectonically active regions. The study of weak-to-moderate earthquakes can improve the characterization of the potentially destructive seismic hazard of this particular area, already struck by M 〉 6.5 episodes in the past. In this work, we analyze the source parameters of this Mw 4 earthquake by applying advanced seismological techniques to estimate the uncertainties derived from the moment tensor inversion and identify plausible directivity effects. The moment tensor is dominated by a NW–SE oriented normal faulting with a centroid depth of 14 km. A single ML 2.1 aftershock was recorded and used as the empirical Green’s function to calculate the apparent source time function for the mainshock. Apparent durations (in the range 0.11–0.21 s, obtained from S-waves) define an azimuthal pattern, which reveals an asymmetric bilateral rupture with 70% of the rupture propagation in the N310°Wdirection, suggesting a rupture plane dipping to the SW. Our results tally with the activation of a deeper fault segment associated with the Eastern Agri Fault System close to the basement as the origin of the Montesano earthquake. Finally, the Coulomb stress rate induced by depletion of the oilfield is calculated to quantify the trigger potential estimated for the Montesano earthquake yielding relatively low probabilities below 10%. Our analyses point toward the conclusion that the Mw 4 event was more likely due to the local natural tectonic stress, rather than induced or triggered by the long-term hydrocarbon extraction in the Val d’Agri oilfield.
    Beschreibung: Published
    Beschreibung: 617794
    Beschreibung: 3T. Fisica dei terremoti e Sorgente Sismica
    Beschreibung: JCR Journal
    Schlagwort(e): earthquake source ; induced seismicity ; directivity ; triggered earthquake ; Val d’Agri oilfield ; 04.06. Seismology
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Publikationsdatum: 2021-05-12
    Beschreibung: In order to monitor temporal and spatial crustal activities associated with earthquakes, ground- and satellite-based monitoring systems have been installed in China since the 1990s. In recent years, the correlation between monitoring strain anomalies and local major earthquakes has been verified. In this study, we further evaluate the possibility of strain anomalies containing earthquake precursors by using Receiver Operating Characteristic (ROC) prediction. First, strain network anomalies were extracted in the borehole strain data recorded in Western China during 2010–2017. Then, we proposed a new prediction strategy characterized by the number of network anomalies in an anomaly window, Nano, and the length of alarm window, Talm. We assumed that clusters of network anomalies indicate a probability increase of an impending earthquake, and consequently, the alarm window would be the duration during which a possible earthquake would occur. The Area Under the ROC Curve (AUC) between true predicted rate, tpr, and false alarm rate, fpr, is measured to evaluate the efficiency of the prediction strategies. We found that the optimal strategy of short-term forecasts was established by setting the number of anomalies greater than 7 within 14 days and the alarm window at one day. The results further show the prediction strategy performs significantly better when there are frequent enhanced network anomalies prior to the larger earthquakes surrounding the strain network region. The ROC detection indicates that strain data possibly contain the precursory information associated with major earthquakes and highlights the potential for short-term earthquake forecasting.
    Beschreibung: National Natural Science Foundation of China under Grant 41974084 Ministry of Education, Culture, Sports, Science and Technology (MEXT) of Japan, under its observation and Research Program for Prediction of Earthquakes and Volcanic Eruptions.
    Beschreibung: Published
    Beschreibung: 515
    Beschreibung: 7T. Variazioni delle caratteristiche crostali e precursori sismici
    Beschreibung: JCR Journal
    Schlagwort(e): receiver operating characteristic ; a new prediction strategy ; frequent network anomalies ; prediction efficiency ; short-term earthquake forecasting ; 04.06. Seismology
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 3
    Publikationsdatum: 2021-02-02
    Beschreibung: Abstract: In this paper we review and discuss the seismic method based on the analysis of seismic coda waves used in the last 10 years by the present authors and/or their co-workers, to produce separate images of intrinsic- and scattering attenuation in zones of peculiar geological interest (mainly volcanoes). Such separate attenuation images are considered by the scientific community as complementary to those from ordinary velocity-tomography and useful to improve the geological interpretation in volcanoes and in tectonically active zones. In this review we only list but do not discuss the most significative papers showing the images obtained, as we are focused to review the method and not the interpretation of data analysis. For sake of completeness, we anyway show also a new analysis applied to data from Stromboli volcano. We thus first introduce the physical model describing the seismogram Energy Envelope (derived from the solution of the Energy Transport integral Equation) and discuss its asymptotic approximations (Diffusion- and Single-scattering model). Then, we describe a numerical method to heuristically calculate the Sensitivity Kernels for the propagation of the scattered waves in the assumption of isotropic scattering. We attribute to these Sensitivity Kernels the physical meaning of probability that for a single source-receiver couple the measured attenuation parameters can be associated with the space coordinates. Based on this definition, the attenuation image can be obtained mapping the estimated attenuation parameters onto the zone under study weighting with the Sensitivity Kernels. We further discuss how to estimate the uncertainties associated with the results and report the list of the papers describing the (separated) scattering- and intrinsic-attenuation structures investigated using this approach.
    Beschreibung: Published
    Beschreibung: id304
    Beschreibung: 1T. Struttura della Terra
    Beschreibung: JCR Journal
    Schlagwort(e): seismic scattering ; seismic imaging ; sensitivity kernels ; seismic attenuation ; 04.06. Seismology
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 4
    Publikationsdatum: 2021-04-13
    Beschreibung: Recently, a new strain rate map of Italy and the surrounding areas has been obtained by processing data acquired by the persistent scatterers (PS) of the synthetic aperture radar interferome- try (InSAR) satellites—ERS and ENVISAT—between 1990 and 2012. This map clearly shows that there is a link between the strain rate and all the shallow earthquakes (less than 15 km deep) that occurred from 1990 to today, with their epicenters being placed only in high strain rate areas (e.g., Emilia plain, NW Tuscany, Central Apennines). However, the map also presents various regions with high strain rates but in which no damaging earthquakes have occurred since 1990. One of these regions is the Apennine sector, formed by Sannio and Irpinia. This area represents one of the most important seismic districts with a well-known and recorded seismicity from Roman times up to the present day. In our study, we merged historical records with new satellite techniques that allow for the precise determination of ground movements, and then derived physical dimensions, such as strain rate. In this way, we verified that in Irpinia, the occurrence of new strong shocks—forty years after one of the strongest known seismic events in the district that occurred on the 23 November 1980, measuring Mw 6.8—is still a realistic possibility. The reason for this is that, from 1990, only areas characterized by high strain rates have hosted significant earthquakes. This picture has been also confirmed by analyzing the historical catalog of events with seismic completeness for magnitude M ≥ 6 over the last four centuries. It is easy to see that strong seismic events with magnitude M ≥ 6 generally occurred at a relatively short time distance between one another, with a period of 200 years without strong earthquakes between the years 1732 and 1930. This aspect must be considered as very important from various points of view, particularly for civil protection plans, as well as civil engineering and urban planning development.
    Beschreibung: Published
    Beschreibung: 168
    Beschreibung: 4T. Sismicità dell'Italia
    Beschreibung: JCR Journal
    Schlagwort(e): Irpinia ; seismic hazard ; strain rate ; GNSS ; InSAR ; earthquake ; 04.06. Seismology
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 5
    Publikationsdatum: 2021-01-29
    Beschreibung: The first 5.3 years of magnetic data from three Swarm satellites have been systematically analyzed, and possible co-seismic magnetic disturbances in the ionosphere were investigated just a few minutes after the occurrence of large earthquakes. We preferred to limit the investigation to a subset of earthquakes selected in function of depth and magnitude. After a systematic inspection of the available data around (in time and space) the seismic events, we found 12 Swarm satellite tracks with co-seismic disturbances possibly produced by ten earthquakes from Mw5.6 to Mw6.9. The distance of the satellite to the earthquake epicenter corresponds to the measured distance-time arrival of the disturbance from the surface to the ionosphere, confirming that the identified disturbances are most likely produced by the seismic events. Secondly, we found a good agreement with a model that combined a propagation of the disturbance to the F2 ionospheric layer with an acoustic gravity wave at a velocity of about (2.2 0.3) km/s and a second faster phenomenon that transmits the disturbance from F2 layer to the Swarm satellite with a velocity of about (16 3) km/s as an electromagnetic scattering propagation.
    Beschreibung: Published
    Beschreibung: 1166
    Beschreibung: 7T. Variazioni delle caratteristiche crostali e precursori sismici
    Beschreibung: JCR Journal
    Schlagwort(e): coseismic phenomena ; ionospheric phenomena ; 01.02. Ionosphere ; 04.05. Geomagnetism ; 04.06. Seismology
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 6
    Publikationsdatum: 2021-04-30
    Beschreibung: On 24 August 2016, a Mw 6.0 earthquake started a damaging seismic sequence in central Italy. The historical center of Amatrice village reached the XI degree (MCS scale) but the high vulnerability alone could not explain the heavy damage. Unfortunately, at the time of the earthquake only AMT station, 200 m away from the downtown, recorded the mainshock, whereas tens on temporary stations were installed afterwards. We propose a method to simulate the ground motion affecting Amatrice, using the FFT amplitude recorded at AMT, which has been modified by the standard spectral ratio (SSR) computed at 14 seismic stations in downtown. We tested the procedure by comparing simulations and recordings of two later mainshocks (Mw 5.9 and Mw 6.5), underlining advantages and limits of the technique. The strong motion variability of simulations was related to the proximity of the seismic source, accounted for by the ground motion at AMT, and to the peculiar site effects, described by the transfer function at the sites. The largest amplification characterized the stations close to the NE hill edge and produced simulated values of intensity measures clearly above one standard deviation of the GMM expected for Italy, up to 1.6 g for PGA.
    Beschreibung: The grant of A.T. is funded by INGV and Department of Sciences, Roma Tre University (MIUR-Italy Dipartimenti di Eccellenza, Art.1, Commi 314-337 Legge 232/2016).
    Beschreibung: Published
    Beschreibung: 186
    Beschreibung: 5T. Sismologia, geofisica e geologia per l'ingegneria sismica
    Beschreibung: JCR Journal
    Schlagwort(e): strong ground motion ; earthquake simulation ; near-source ; Amatrice earthquake ; seismic sequence ; site effects ; 04.06. Seismology
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 7
    Publikationsdatum: 2022-03-07
    Beschreibung: Coastal and ocean island volcanoes are renowned for having unstable flanks. This can lead to flank deformation on a variety of temporal and spatial scales ranging from slow creep to catastrophic sector collapse. A large section of these unstable flanks is often below sea level, where information on the volcano-tectonic structure and ground deformation is limited. Consequently, kinematic models that attempt to explain measured ground deformation onshore associated with flank instability are poorly constrained in the offshore area. Here, we attempt to determine the locations and the morpho-tectonic structures of the boundaries of the submerged unstable southeastern flank of Mount Etna (Italy). The integration of new marine data (bathymetry, microbathymetry, offshore seismicity, reflection seismic lines) and published marine data (bathymetry, seafloor geodesy, reflection seismic lines) allows identifying the lineament north of Catania Canyon as the southern lateral boundary with a high level of confidence. The northern and the distal (seaward) boundaries are less clear because no microbathymetric or seafloor geodetic data are available. Hypotheses for their locations are presented. Geophysical imaging suggests that the offshore Timpe Fault System is a shallow second-order structure that likely results from extensional deformation within the moving flank. Evidence for active uplift and compression upslope of the amphitheater-shaped depression from seismic data along with subsidence of the onshore Giarre Wedge block observed in ground deformation data leads us to propose that this block is a rotational slump, which moves on top of the large-scale instability. The new shoreline-crossing structural assessment may now inform and improve kinematic models.
    Beschreibung: Published
    Beschreibung: 810790
    Beschreibung: 2V. Struttura e sistema di alimentazione dei vulcani
    Beschreibung: JCR Journal
    Schlagwort(e): seafloor ; fault ; flank dynamics ; hydroacoustic ; geodesy ; seismic profiles ; 04.07. Tectonophysics ; 04.08. Volcanology ; 04.06. Seismology ; 04.02. Exploration geophysics ; 05.02. Data dissemination
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Publikationsdatum: 2021-09-21
    Beschreibung: Passive seismic interferometry has become very popular in recent years in explorationgeophysics. However, it has not been widely applied in marine exploration. The purpose of thisstudy is to investigate the internal structure of a quasi-amagmatic portion of the Southwest IndianRidge by interferometry and to examine the performance and reliability of interferometry in marineexplorations. To reach this goal, continuous vertical component recordings from 43 ocean bottomseismometers were analyzed. The recorded signals from 200 station pairs were cross-correlated inthe frequency domain. The Bessel function method was applied to extract phase–velocity dispersioncurves from the zero crossings of the cross-correlations. An average of all the dispersion curveswas estimated in a period band 1–10 s and inverted through a conditional neighborhood algorithmwhich led to the final 1D S-wave velocity model of the crust and upper mantle. The obtained S-wavevelocity model is in good agreement with previous geological and geophysical studies in the regionand also in similar areas. We find an average crustal thickness of 7 km with a shallow layer of lowshear velocities and high Vp/Vs ratio. We infer that the uppermost 2 km are highly porous and maybe strongly serpentinized.
    Beschreibung: Published
    Beschreibung: 2811
    Beschreibung: 1T. Struttura della Terra
    Beschreibung: JCR Journal
    Schlagwort(e): 04.06. Seismology ; 04.01. Earth Interior
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 9
    Publikationsdatum: 2021-11-30
    Beschreibung: Historical seismic catalogs report that the Gargano Promontory (southern Italy) was affected in the past by earthquakes with medium to high estimated magnitude. From the instrumental seismicity, it can be identified that the most energetic Apulian sequence occurred in 1995 with a main shock of MW = 5.2 followed by about 200 aftershocks with a maximum magnitude of 3.7. The most energetic earthquakes of the past are attributed to right-lateral strike-slip faults, while there is evidence that the present-day seismicity occur on thrust or thrust-strike faults. In this article, we show a detailed study on focal mechanisms and stress field obtained by micro-seismicity recorded from April 2013 until the present time in the Gargano Promontory and surrounding regions. Seismic waveforms are collected from the OTRIONS Seismic Network (OSN), from the Italian National Seismic Network (RSN), and integrated with data from the Italian National Accelerometric Network (RAN) in order to provide a robust dataset of earthquake localizations and focal mechanisms. The effect of uncertainties of the velocity model on fault plane solutions (FPS) has been also evaluated indicating the robustness of the results. The computed stress field indicates a deep compressive faulting with maximum horizontal compressive stress, SHmax, trending NW-SE. The seismicity pattern analysis indicates that the whole crust is seismically involved up to a depth of 40 km and indicates the presence of a low-angle seismogenic surface trending SW-NE and dipping SE-NW, similar to the Gargano–Dubrovnik lineament. Shallower events, along the eastern sector of the Mattinata Fault (MF), are W-E dextral strike-slip fault. Therefore, we hypothesized that the seismicity is locally facilitated by preexisting multidirectional fractures, confirmed by the heterogeneity of focal mechanisms, and explained by the different reactivation processes in opposite directions over the time, involving the Mattinata shear zone.
    Beschreibung: Published
    Beschreibung: 589332
    Beschreibung: 4T. Sismicità dell'Italia
    Beschreibung: JCR Journal
    Schlagwort(e): Gargano promontory ; OTRIONS local seismic network ; focal mechanisms ; stress field ; microseismicity ; mattinata fault ; gargano-dubrovnik lineament ; 04.06. Seismology
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Publikationsdatum: 2022-02-18
    Beschreibung: We applied a new version of physics-based earthquake simulator upon a seismogenic model of the Italian seismicity derived from the latest version of the Database of Individual Seismogenic Sources (DISS). We elaborated appropriately for their use within the simulator all fault systems identified in the study area. We obtained synthetic catalogs spanning hundreds of thousands of years. The resulting synthetic seismic catalogs exhibit typical magnitude, space and time features that are comparable to those obtained by real observations. A typical aspect of the observed seismicity is the occurrence of earthquake sequences characterized by multiple main shocks of similar magnitude. Special attention was devoted to verifying whether the simulated catalogs include this notable aspect, by the use of an especially developed computer code. We found that the phenomenon of Coulomb stress transfer from causative to receiving source patches during an earthquake rupture has a critical role in the behavior of seismicity patterns in the simulated catalogs. We applied the simulator to the seismicity of the northern and central Apennines and compared the resulting synthetic catalog with the observed seismicity for the period 1650–2020. The result of this comparison supports the hypothesis that the occurrence of sequences containing multiple mainshocks is not just a casual circumstance.
    Beschreibung: Published
    Beschreibung: 2062
    Beschreibung: 2T. Deformazione crostale attiva
    Beschreibung: 3T. Fisica dei terremoti e Sorgente Sismica
    Beschreibung: 4T. Sismicità dell'Italia
    Beschreibung: JCR Journal
    Schlagwort(e): numerical modeling ; earthquake simulator ; statistical methods ; earthquake clustering ; 04.06. Seismology ; 04.07. Tectonophysics
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
    Standort Signatur Erwartet Verfügbarkeit
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