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  • 04.06. Seismology  (23)
  • Nature PG  (11)
  • Wiley-Agu  (7)
  • Copernicus Publications  (3)
  • Wiley
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Years
  • 11
    Publication Date: 2023-12-01
    Description: On March 5, 2022, a 12 kg meteoroid crossed the sky above Central Italy and was observed by three different observational systems: the PRISMA all-sky camera network (10 stations), the Italian national seismic network (61 stations), and a 4-element infrasound array. The corresponding datasets, each with its own resolution, provided three independent assessments of the trajectory, size and speed of the meteoroid. The bolide traveled across central Italy with an azimuth of 102 degrees, becoming visible at about 91 km above sea level with a velocity of about 15.4 km/s. Its visible trajectory lasted about 15 s. Reasonably, the residual portion of the ablated bolide terminated its path in the Adriatic Sea and could not be recovered. Seismic and infrasound data well match optical observations detecting the bolide Mach cone at 68 km above sea level with a back azimuth of 25 degrees with respect to the array. By comparing results from the three different systems, discrepancies are within the estimated uncertainties, thus confirming the mutual consistency of the adopted methodologies. Therefore, this study shows that different approaches can be integrated to improve the detection capability for bolide crossing the sky in monitored regions.
    Description: Published
    Description: 21135
    Description: OST5 Verso un nuovo Monitoraggio
    Description: JCR Journal
    Keywords: meteorites ; meteorites ; 04.06. Seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 12
    Publication Date: 2023-03-20
    Description: The deformation style of the continental lithosphere is a relevant issue for geodynamics and seismic hazard perspectives. Here we show the first evidence of two well-distinct low-angle and SW-dipping individual reverse shear zones of the Italian Outer Thrust System in Central Italy. One corresponds to the down-dip prosecution of the Adriatic Basal Thrust with its major splay and the other to a hidden independent structure, illuminated at a depth between 25 and 60 km, for an along-strike extent of ~ 150 km. Combining geological information with high-quality seismological data, we unveil this novel configuration and reconstruct a detailed 3D geometric and kinematic fault model of the compressional system, active at upper crust to upper mantle depths. In addition, we report evidence of coexisting deformation volumes undergoing well-distinguished stress fields at different lithospheric depths. These results provide fundamental constraints for a forthcoming discussion on the Apennine fold-and-thrust system's geodynamic context as a shallow subduction zone or an intra-continental lithosphere shear zone.
    Description: Published
    Description: 21066
    Description: 2T. Deformazione crostale attiva
    Description: JCR Journal
    Keywords: 04.06. Seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 13
    Publication Date: 2023-02-03
    Description: The protracted nature of the 2016-2017 central Italy seismic sequence, with multiple damaging earthquakes spaced over months, presented serious challenges for the duty seismologists and emergency managers as they assimilated the growing sequence to advise the local population. Uncertainty concerning where and when it was safe to occupy vulnerable structures highlighted the need for timely delivery of scientifically based understanding of the evolving hazard and risk. Seismic hazard assessment during complex sequences depends critically on up-to-date earthquake catalogues-i.e., data on locations, magnitudes, and activity of earthquakes-to characterize the ongoing seismicity and fuel earthquake forecasting models. Here we document six earthquake catalogues of this sequence that were developed using a variety of methods. The catalogues possess different levels of resolution and completeness resulting from progressive enhancements in the data availability, detection sensitivity, and hypocentral location accuracy. The catalogues range from real-time to advanced machine-learning procedures and highlight both the promises as well as the challenges of implementing advanced workflows in an operational environment.
    Description: Published
    Description: 710
    Description: 4T. Sismicità dell'Italia
    Description: JCR Journal
    Keywords: earthquakes catalogue ; 04.06. Seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 14
    Publication Date: 2022-08-23
    Description: Intermediate depth (70-300 km) and deep (〉300 km) earthquakes have always been puzzling Earth scientists: their occurrence is a paradox, since the ductile behavior of rocks and the high confining pressure with increasing depths would theoretically preclude brittle failure and frictional sliding. The mechanisms proposed to explain deep earthquakes, mainly depending on the subducting plate age and stress state, are generally expressed by single parameters, unsuitable to comprehensively account for differences among distinct subduction zones or within the same slab. We analyze the Kurile and Izu-Bonin intraslab seismicity and detail the stress state along the subducted planes using the Gutenberg-Richter b-value. We demonstrate that, despite the slabs different properties (e.g., lithospheric age, stress state, dehydration rate), in both cases deep earthquakes are restricted to depths characterized by equal age from subduction initiation and are driven by stress regimes affected by the persistence of the metastable olivine wedge.
    Description: Published
    Description: 12440
    Description: 3T. Fisica dei terremoti e Sorgente Sismica
    Description: JCR Journal
    Keywords: Subduction ; Gutenberg-Richter b value ; Metastable olivine wedge ; NW Pacific ; 04. Solid Earth ; 04.06. Seismology ; 04.07. Tectonophysics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 15
    Publication Date: 2022-05-06
    Description: The high seismic productivity of volcanic areas provides the chance to investigate the local stress conditions with great resolution, by analysing the slope of the frequency-magnitude distribution of earthquakes, namely the b-value. Here we investigated the seismicity of Mt. Etna between 2005 and 2019, focusing on one of the largest known episodes of unrest in December 2018, when most of the intruding magma aborted, rather oddly, its ascent inside the volcano. We found a possible stress concentration zone along magma pathways, which may have inhibited the occurrence of a larger eruption. If the origin of such hypothetical loaded region is related to tectonic forces, one must consider the possibility that geodynamic processes can locally result in such rapid crustal strain as to perturb the release of magma. Strong b-value time-variations occurred a few days before the unrest event, suggesting new possibilities for investigating the volcano state and impending eruptions.
    Description: Published
    Description: 68
    Description: 1T. Struttura della Terra
    Description: 1V. Storia eruttiva
    Description: 2V. Struttura e sistema di alimentazione dei vulcani
    Description: 4V. Processi pre-eruttivi
    Description: 5V. Processi eruttivi e post-eruttivi
    Description: JCR Journal
    Keywords: 04.06. Seismology ; 04.08. Volcanology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 16
    Publication Date: 2022-03-25
    Description: Campi Flegrei caldera (Southern Italy) is one of the most hazardous volcanic complexes in the world since it is located inside the densely inhabited urban district of Naples-Pozzuoli. In the past, the caldera has produced devastating to moderate eruptions and periodically undergoes from strong to minor uplift episodes, named “bradyseism”, almost always accompanied by seismic swarms. Starting from 2005 Campi Flegrei has undergone an unrest crisis, characterized by ground uplift, localized gas emissions and seismicity, often occurring in seismic swarms. As a consequence, the monitoring activities have been progressively increasing, producing a huge amount of data, difficult to manage and match. GIS (Geographical Information System) represents a potent tool to manage great quantity of data, coming from different disciplines. In this study, we show two GIS technology applications to the seismic catalogue of Campi Flegrei. In the first one, a high-quality dataset is extracted from the GeoDatabase addressed to seismological studies that require high precision earthquake locations. In the second application, GIS are used to extract, visualize and analyse the typical seismic swarms of Campi Flegrei. Moreover, density and seismic moment distribution maps were generated for these swarms. In the last application, the GIS allow to highlight a clear variation in the temporal trend of the seismic swarms at Campi Flegrei.
    Description: This study has benefited from funding provided by the Italian Presidenza del Consiglio dei Ministri – Dipartimento della Protezione Civile.
    Description: Published
    Description: 131-144
    Description: 4V. Processi pre-eruttivi
    Description: 6SR VULCANI – Servizi e ricerca per la società
    Description: 1IT. Reti di monitoraggio e sorveglianza
    Description: N/A or not JCR
    Keywords: Campi Flegrei ; Seismic swams ; Seismic network ; GIS ; 04.06. Seismology ; 04.08. Volcanology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 17
    Publication Date: 2022-02-22
    Description: One of the most effective approaches to identifying possible precursors of eruptions is the analysis of seismicity patterns recorded at volcanoes. Accurate locations of the seismicity and the estimate of source mechanisms can resolve fault systems and track fluid migrations through volcanoes. We analysed the six main swarms recorded at Campi Flegrei since 2000, using them as a proxy of the processes involved in the long-term-unrest of this densely populated caldera. We re-located the earthquakes comprised in these swarms and estimated the focal mechanisms, which appear in agreement with the fault systems of the caldera and with tomographic images. The focal mechanisms are in agreement with the tensional stress induced by the caldera uplift. Most of the swarms and remaining seismicity delineate a highly fractured volume extending vertically below the Solfatara/ Pisciarelli vents, where gases find preferential paths to the surface triggering earthquakes. The main swarms are located below this volume where the presence of a rigid caprock is still debated. We interpreted the current unrest in term of a gradual increment in the activity of a wide hydrothermal system whose most evident manifestation is the enlargement of the fumarolic-field of Pisciarelli and the increment of the earthquakes occurrence rate.
    Description: Published
    Description: 2900
    Description: 2V. Struttura e sistema di alimentazione dei vulcani
    Description: JCR Journal
    Keywords: Campi Flegrei ; swarm ; volcano seismicity ; 04.08. Volcanology ; 04.06. Seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 18
    Publication Date: 2021-11-25
    Description: Ambient noise polarizes inside fault zones, yet the spatial and temporal resolution of polarized noise on gas-bearing fluids migrating through stressed volcanic systems is unknown. Here we show that high polarization marks a transfer structure connecting the deforming centre of the caldera to open hydrothermal vents and extensional caldera-bounding faults during periods of low seismic release at Campi Flegrei caldera (Southern Italy). Fluids pressurize the Campi Flegrei hydrothermal system, migrate, and increase stress before earthquakes. The loss of polarization (depolarization) of the transfer and extensional structures maps pressurized fluids, detecting fluid migrations after seismic sequences. After recent intense seismicity (December 2019-April 2020), the transfer structure appears sealed while fluids stored in the east caldera have moved further east. Our findings show that depolarized noise has the potential to monitor fluid migrations and earthquakes at stressed volcanoes quasi-instantaneously and with minimum processing.
    Description: Published
    Description: 6656
    Description: 4V. Processi pre-eruttivi
    Description: JCR Journal
    Keywords: Campi Flegrei ; seismic noise ; polarization ; fluid migration ; 04.06. Seismology ; 04.08. Volcanology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 19
    Publication Date: 2021-09-22
    Description: We evaluate, by numerical tests, whether surface-wave attenuation can be determined from ambient-noise data. We generate synthetic recordings of numerically simulated ambient seismic noise in several experimental setups, characterized by different source distributions and different values of attenuation coefficient. We use them to verify that the source spectrum can be reconstructed from ambient recordings (provided that the density of sources and the attenuation coefficient are known) and that true attenuation can be retrieved from normalized cross correlations of synthetic signals. We then apply the so validated method to real continuous recordings from 33 broadband receivers distributed within the Colorado Plateau and Great Basin. A preliminary analysis of the signal-to-noise ratio as a function of azimuth reveals a SW-NE preferential directionality of the noise sources within the secondary microseism band (6–8s), consistent with previous studies. By nonlinear inversion of noise data we find the attenuation coefficient in the area of interest to range from ~1×10^-5 m^-1 at 0.3Hz to 4.5×10^-7 m^-1 at 0.065Hz, and confirm the statistical robustness of this estimate by means of a bootstrap analysis. The result is compatible with previous observations based on both earthquake-generated and ambient Rayleigh waves. In this regard, the method proves to be promising in accurately quantifying surface-wave attenuation at relatively high frequencies.
    Description: Published
    Description: e2020JB019865
    Description: 1T. Struttura della Terra
    Description: JCR Journal
    Keywords: 04.01. Earth Interior ; 04.06. Seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 20
    Publication Date: 2021-09-21
    Description: Mapping variations in the attenuation of seismic energy is important for understanding dissipative mechanisms in the lithosphere, and for modeling ground shaking associated with earthquakes. We cross-correlate ambient seismic signal recorded across the EarthScope Transportable Array in the 3-15 s period range. We apply to the resulting cross correlations a new method to estimate lateral variations in Rayleigh-wave attenuation, as a function of period, beneath North America. Between 3 and 6 s, our maps are dominated by a strong eastward decrease in attenuation. This pattern vanishes at longer periods, confirming early observations based on regional earthquakes. Attenuation maps and phase-velocity maps are anti-correlated at periods between 3 and 6 s, but the anti-correlation is also largely lost at longer periods. This corresponds to the attenuation coefficient decreasing with period more rapidly in the west than in the east, while the change in phase velocity with period is more uniform across the continent. Our results point to a transition in the properties of upper-crustal materials with depth, probably related to the closure of fluid-filled cracks and pores, and imply that measures of attenuation from seismic noise carry significant information on crustal rheology.
    Description: Published
    Description: 10149
    Description: 1T. Struttura della Terra
    Description: JCR Journal
    Keywords: 04.01. Earth Interior ; 04.06. Seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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