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  • 1
    Publication Date: 2021-01-05
    Description: We use seismic data together with a subglacial bedrock relief from the BEDMAP2 database to obtain a new three- layer model of the consolidated (crystalline) crust of Antarctica that locally improves the global seismic crustal model CRUST1.0. We collect suitable data for constructing crustal layers, analyse them and build maps of the crustal layer thickness and seismic velocities. We use the subglacial relief according to a tectonic configuration and then interpolate data using a statistical kriging method. The P-wave velocity information from old seismic profiles have been supplemented with the new shear-wave velocity models. We adjust the thickness of crustal layers by multiplying a total crustal thickness by a percentage ratio of each individual layer at each point. Our re- sults reveal large variations in seismic velocities between different crustal blocks forming Antarctica. The most pronounced differences exist between East and West Antarctica. In East Antarctica, a high P-wave velocity (vP 〉 7 km/s) layer in the lower crust is absent. The P-wave velocity in the lower crust changes from 6.1 km/s beneath the Lambert Rift to 6.9 km/s beneath the Wilkes Basin. In West Antarctica, a thick mafic lower crust is characterized by large P-wave velocities, ranging from 7.0 km/s under the Ross Sea to 7.3 km/s under the Byrd Basin. In contrast, velocities in the lower crust beneath the Transantarctic and Ellsworth-Whitmore Mountains are ~6.8 km/s. The P-wave velocities in the upper crust in East Antarctica are within the range 5.5–6.4 km/s. The upper crust of West Antarctica is characterized by the P-wave velocities of 5.6–6.3 km/s. The P-wave veloc- ities in the middle crust vary within 5.9–6.6 km/s in East Antarctica and within 6.3–6.5 km/s in West Antarctica. A low-velocity layer (5.8–5.9 km/s) is detected at depth of ~20–25 km beneath the Princes Elizabeth Land.
    Description: Published
    Description: 1-18
    Description: 1T. Struttura della Terra
    Description: JCR Journal
    Keywords: Crustal structure ; Sediments ; Antarctica ; Gondwana ; 04.06. Seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
    Publication Date: 2021-06-18
    Description: Questa è una traduzione commentata del raro documento citato da oltre un secolo di bibliografia come “Milne, 1890”. Si è studiato il testo per verificare la realisticità di alcune recenti affermazioni sul fatto che questo rapporto (oggi difficilmente reperibile) avesse trattato per la prima volta di precursori elettromagnetici. Si è cercato di indagare su ogni episodio e personaggio, identificando i criptici (e a volte inesistenti) riferimenti bibliografici, rintracciando quasi tutti i testi, ampliando e commentando spesso le relative citazioni. La mia opinione è che nessuno all’epoca di Milne avesse consapevolmente, ma forse nemmeno accidentalmente, osservato un precursore di origine elettromagnetica. I fenomeni descritti sono studiati da un punto di vista puramente elettrico o magnetico. I segnali elettrici riguardano tensioni e correnti troppo alte. I fenomeni magnetici già all’epoca furono contestati come prodotti di effetti inerziali ma comunque è difficile pensare che la componente campo magnetico di un segnale EM possa deviare stabilmente l’ago di una bussola. Questa stessa ricerca ha tuttavia portato alla luce qualche altro caso sospetto che sarebbe opportuno indagare in modo più approfondito, in quanto potrebbe risultare realmente il primo caso documentabile dell’osservazione di un precursore elettromagnetico del terremoto.
    Description: This is a commented translation of the rare document cited by more than a century of bibliography as "Milne, 1890". The text was studied to verify the veracity of some recent claims that this report (presently difficult to find) had dealt with electromagnetic precursors for the first time. An attempt was made to investigate each episode and character, identifying the cryptic (and sometimes non-existent) bibliographic references, tracing almost all the texts, often expanding and commenting on the relative citations. My opinion is that no one, at the time of Milne, had consciously, but maybe not even accidentally, observed a precursor of electromagnetic origin. The phenomena described are studied from either a purely electrical or magnetic point of view. Electrical signals concern too high voltages and currents. Magnetic phenomena, already at the time, were contested as products of inertial effects, but in any case it is difficult to think that the magnetic field component of an EM signal can permanently deflect the needle of a compass. However this same research has brought to light some other potentially interesting cases that should be investigated further. One of them, could actually be the first documentable case of the observation of an electromagnetic seismic precursor.
    Description: Progetto INGV “Pianeta Dinamico” (codice progetto INGV 1020.010) finanziato dal MIUR ("Fondo finalizzato al rilancio degli investimenti delle amministrazioni centrali dello Stato e allo sviluppo del Paese", legge 145/2018).
    Description: Published
    Description: 1-48
    Description: 2TM. Divulgazione Scientifica
    Description: JCR Journal
    Keywords: Earthquake ; electric precursors ; magnetic precursors ; precursorori ; terremoto ; electromagnetic precursors ; precursori elettromagnetici ; John Milne ; 04.06. Seismology ; 05.03. Educational, History of Science, Public Issues
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 3
    Publication Date: 2021-09-13
    Description: Among the geologic data, trenching records of paleoearthquakes represent an important input for the development of seismic hazard evaluations and, specifically, for the characterization of fault rupture behavior in time. Based on the available paleoseismological trenching data in the Central Apennines we have compiled a new database of surface faulting earthquakes for 10 faults. The compilation contains 109 surface faulting events, occurred in the past ~28 kyr. Events younger than 7 kyr (59 dated events) are much better constrained and, therefore, are the basis for most of the analyses. Through a quantitative multistep method, we integrate paleoseismic trench data and treat them statistically, providing relevant improvement needed for trenching-based seismic hazard evaluation. Indeed, the combined analysis of trenching data from multiple sites on the same fault led to a reduction of the approximations and uncertainties in the rupture history of individual faults. The procedure was also applied on specific fault systems and indicated that the single faults may have occasionally ruptured simultaneously, or close in time, in the past. The whole set of age ranges was also statistically analyzed to produce regional earthquake scenarios for a period much longer than the millennial historical record. The built scenarios for the last 7 kyr define a regional mean inter event time (IET) of 230-240 yr, comparable with the average recurrence time of about 200 yr, considering the number of events in time. We also identify the possible occurrence of earthquake storms, i.e., concentration of surface faulting earthquakes in the region within time periods of 200 yr, suggesting a variability in time of the seismic behavior of the faults, with alternation of peaks of activity with more “quiet” periods. Even though the paleoseismic data from the Apennines contains uncertainties, the results appear quite stable and promising for future applications in earthquake-hazard assessment.
    Description: Published
    Description: 229016
    Description: 6T. Studi di pericolosità sismica e da maremoto
    Description: JCR Journal
    Keywords: Paleoseismology ; Statistical modeling ; Surface rupture scenarios ; Regional earthquake recurrence ; Earthquake storms ; Central Apennines ; 04.04. Geology ; 04.06. Seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 4
    Publication Date: 2020-12-18
    Description: probably confirm this opinion, with qualifica ons. Historical earthquake catalogues, up to CPTI11 [Rovida et al., 2011], report only one Mw 5.1 event on 13 November 1948: it was located in the Sardinian Sea, and had very modest effects on land. In later decades, the seismic networks did record very few earthquakes of moderate energy (Mw 〈5), mostly located off-shore, either south-east of Cagliari or west of Olbia or in the Sea of Sardinia. The most recent ones (occurred in 2000, 2004 and 2006) had very slight effects on the island. Given the low level of instrumental seismicity and the weak macroseismic effects of known historical earthquakes, Sardinia's seismic risk is perceived as very low. The low seismicity of the region certainly has a geological explana on, given that the Corsica-Sardinia block is among the most stable areas of the Mediterranean basin. “Low”, however, does not mean “non- existent”: recent historical research has improved knowledge on the major known historical earthquake of Sardinia (it occurred on June 4, 1616 and was responsible for minor but widespread damage to the system of coastal watchtowers, south-west of Cagliari) and rediscovered several minor earthquakes, part of which were known to the seismological tradi on but had been almost completely forgo en. This paper collects all the documenta on available at present on the seismic history of Sardinia.
    Description: Published
    Description: 1-160
    Description: 4T. Sismicità dell'Italia
    Description: JCR Journal
    Keywords: Sardinia ; Seismicity ; Seismic history ; Historical Earthquakes ; Historical seismology ; 04.06. Seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 5
    Publication Date: 2021-02-19
    Description: Questo rapporto tecnico descrive le attività svolte da SISMIKO [Moretti et al., 2012; 2016a; 2016b; Pondrelli et al., 2016] in occasione della sequenza sismica che ha interessato l’area in provincia di Campobasso tra i comuni di Montecilfone, Guardialfiera e Larino a partire dal 14 agosto 2018 e che ha visto nel terremoto di magnitudo ML 5.2 (MW 5.1) del 16 agosto 2018 (18:19 UTC), ben risentito in un’ampia area che comprende molte regioni dell’Italia centro meridionale, l’evento più significativo della sequenza. SISMIKO è uno dei gruppi operativi dell’Istituto Nazionale di Geofisica e Vulcanologia (INGV) per la gestione delle emergenze sismiche [Pondrelli et al., 2016], e come per ogni terremoto con magnitudo superiore a 5.0, ovvero alla soglia prevista nella vigente Convenzione tra l’INGV e il Dipartimento della Protezione Civile (DPC), a seguito del terremoto del 16 agosto 2018 (ML 5.2) ha predisposto un intervento volto al miglioramento del monitoraggio sismico dell’area interessata. L’integrazione di stazioni sismiche temporanee nella geometria della Rete Sismica Nazionale (RSN [Michelini et al., 2016; INGV Seismological Data Centre]), consente infatti un miglioramento nella individuazione dei terremoti e un perfezionamento del calcolo dei parametri ipocentrali, soprattutto della profondità che è strettamente connessa alla distanza media tra le stazioni sismiche. L’intervento principale è stato svolto nella giornata del 17 agosto [SISMIKO working group, 2018], ma nelle due settimane successive i siti allestiti sono stati più volte visitati e il giorno 30 si è proceduto con l’integrazione di ulteriori 2 stazioni, portando a 5 i punti di acquisizione della rete temporanea. La rete sismica è stata operativa per circa 2 mesi. I dati sono stati trasmessi in tempo reale al centro di acquisizione dati della rete mobile presso la sede di Roma di SISMIKO e al contempo integrati nel sistema di sorveglianza sismica INGV [Michelini et al., 2016] per essere utilizzati nelle localizzazioni e nei prodotti scientifici forniti in tempo reale. On 16 August 2018 at 18:19:04 UTC an earthquake with magnitude ML 5.2 (MW 5.1) occurred in the Molise region. The earthquake was felt in a large area including many regions of Central and Southern Italy. The seismologists on duty in the 24H seismic monitoring room of the National Institute of Geophysics and Volcanology (INGV) located the event in the province of Campobasso, 4 km south­east of Montecilfone and at a preliminary depth of 9 km. The same area was affected two days before by a MW 4.6 event (August 14 at 23.48 Italian time1). Following the MW 5.1 event and the associated aftershock sequence, the SISMIKO Operational Group was activated [Moretti et al., 2012; 2016a; 2016b; Pondrelli et al., 2016] for the installation of temporary seismic stations to integrate the permanent stations of the National Seismic Network (RSN [Michelini et al., 2016; INGV Seismological Data Centre]) deployed in the region.
    Description: Published
    Description: 1-32
    Description: 2SR TERREMOTI - Gestione delle emergenze sismiche e da maremoto
    Description: N/A or not JCR
    Keywords: SISMIKO ; Seismic networks temporary ; Seismic emergency ; Molise ; 04.06. Seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 6
    Publication Date: 2020-06-10
    Description: Understanding how long-term subduction dynamics relates to the short-term seismicity and crustal tec tonics is a challenging but crucial topic in seismotectonics. We attempt to address this issue by linking long-term geodynamic evolution with short-term seismogenic deformation in the Northern Apennines. This retreating subduction orogen displays tectonic and seismogenic behaviors on various spatiotemporal scales that also characterize other subduction zones in the Mediterranean area. We use visco-elasto-plastic seismo-thermo-mechanical (STM) modeling with a realistic 2D setup based on available geological and geophysical data. The subduction dynamics and seismicity are coupled in the numerical modeling, and driven only by buoyancy forces, i.e., slab pull. Our results suggest that lower crustal rheology and lithospheric mantle temperature modulate the crustal tectonics of the Northern Apennines, as inferred by previous studies. The observed spatial distribution of upper crustal tectonic regimes and surface displacements requires buoyant, highly ductile material in the subduction channel beneath the internal part of the orogen. This allows protrusion of the asthenosphere in the lower crust and lithospheric delamination associated with slab retreat. The resulting surface velocities and principal stress axes generally agree with present-day observations, suggesting that slab delamination and retreat can explain the dynamics of the orogen. Our simulations successfully reproduce the type and overall distribution of seismicity with thrust faulting events in the external part of the orogen and normal faulting in its internal part. Slab temperatures and lithospheric mantle stiffness affect the cumulative seismic moment release and spatial distribution of upper crustal earthquakes. The properties of deep, sub-crustal material are thus shown to influence upper crustal seismicity in an orogen driven by slab retreat, even though the upper crust is largely decoupled from the lithospheric mantle. Our simulations therefore highlight the effect of deep lower crustal rheologies, self-driven subduction dynamics and mantle properties in controlling shallow deformation and seismicity.
    Description: Published
    Description: 228481
    Description: 1T. Struttura della Terra
    Description: 2T. Deformazione crostale attiva
    Description: JCR Journal
    Keywords: Numerical modeling ; Geodynamics ; Seismotectonics orogen ; Delamination ; Northern Apennines ; 04.06. Seismology ; 04.03. Geodesy ; 05.01. Computational geophysics ; 04.07. Tectonophysics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 7
    Publication Date: 2020-03-03
    Description: The Mw = 7.3 earthquake near the Iran-Iraq border in west Iran (34.911°N, 45.959°E) occurred at 18:18:17 UTC (LT = UTC + 03:30), November 12, 2017 as the result of oblique-thrust faulting at mid-crustal depth (∼19 km). Median, Kalman filter and Neural Network, as three standard, classical and intelligent methods, have been implemented to investigate three months of GPS Total Electron Content (TEC) measurements and to detect the striking anomalous variations around the time and location of the mentioned earthquake. The first method detects unusual variations, 9 days before the event, between 21:00 and 22:00 UTC. The other two methods of Kalman filter and Neural Network detect another clear anomaly on 11 days preceding the earthquake at 16:00 UTC. These findings are two of the outstanding results of GPS-TEC precursor analysis. This paper also presents the results of Swarm satellites (Alpha, Bravo and Charlie) data analysis inside the Dobrovolsky area around the Iran earthquake epicenter during the period from 1 August to 30 November 2017. The time series and orbital analysis of six measured parameters including electron density, electron temperature, magnetic scalar and vectors (X, Y, Z) components indicate irregular variations between 8 and 11 days prior to the occurrence of the earthquake. Since the variations of the solar and geomagnetic indices follow a normal behaviour during the whole period of the observed ionospheric anomalies between 8 and 11 days before the earthquake, it can be concluded that multi-precursors analysis has an important role to acknowledge the seismo-LAI (Lithospheric-Atmospheric-Ionospheric) anomalies associated to strong earthquakes such as this case. Furthermore, some physical and chemical atmospheric parameters from a climatological database are investigated and some interesting anomalies above two standard deviations prior to the earthquake are found. This paper shows not only anomalies in atmosphere and ionosphere but also a contemporary analysis of different data sources to detect the possible Lithosphere Atmosphere Ionosphere Coupling (LAIC) effects.
    Description: ASI
    Description: Published
    Description: 143-158
    Description: 7T. Variazioni delle caratteristiche crostali e precursori sismici
    Description: JCR Journal
    Keywords: Earthquake precursors ; LAIC ; 04.06. Seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 8
    Publication Date: 2020-03-04
    Description: A seguito di un evento sismico al di sopra della soglia del danno, una parte del personale dell’Istituto Nazionale di Geofisica e Vulcanologia (INGV) viene coinvolto nei gruppi di emergenza e si prepara, nel più breve tempo possibile, a partire per raggiungere l’area epicentrale. Ogni gruppo ha il compito di raccogliere dati, effettuare misurazioni e rilievi, per studiare il terremoto sotto diversi punti di vista, e per supportare le attività di Protezione Civile. In questo contesto rientrano le attività di rilievo del gruppo QUEST (QUick Earthquake Survey Team), formato da personale specializzato nel rilievo macrosismico dell’INGV e altri enti, che ha il compito di raggiungere le aree colpite dal sisma per fornire un rilievo degli effetti sull’edificato, sull’ambiente e sulle persone. L’indagine macrosismica che ne deriva, contribuisce allo studio del terremoto attraverso l’osservazione diretta e la classificazione del danno mediante l’utilizzo della scala macrosismica EMS98 [Grünthal, 1998]. Attualmente questa indagine viene svolta con l’ausilio di schede cartacee predisposte per la raccolta del dato ed una serie di mappe, generalmente immagini da satellite, delle località da investigare [Tertulliani et al., 2010]. Nel tempo si è cercato di studiare tecniche di rilievo sempre più rapide al fine di raccogliere il dato reale del danneggiamento prima che gli inevitabili interventi di messa in sicurezza dei vigili del fuoco o ulteriori repliche dannose modifichino lo scenario del danno sull’edificato. Per questo scopo si sta mettendo a punto uno strumento per la raccolta del dato macrosismico di campagna, basato sull’utilizzo di tablets, corredati di una interfaccia grafica tale da permettere la raccolta delle informazioni direttamente su mappe delle località da investigare. In particolare, l’inserimento dell’informazione puntuale per ogni edificio investigato, con il relativo dato di vulnerabilità e grado di danno, permette di condividere le informazioni in tempo reale tra le varie squadre sul terreno. Tale strumento permette inoltre, all’operatore, di lavorare off line e quindi di poter acquisire informazioni anche in assenza di copertura del segnale telefonico e di inviare in un secondo momento i dati. L’informazione viene centralizzata presso la sede operativa che può gestire e coordinare lo spostamento delle squadre nell’area epicentrale. In questo modo si aprono nuovi interessanti scenari sia a vantaggio della rapidità e della conoscenza del danneggiamento dell’edificato, sia in termini di gestione del personale coinvolto per ottimizzare così le operazioni di rilievo.
    Description: Published
    Description: 1-24
    Description: 5T. Sismologia, geofisica e geologia per l'ingegneria sismica
    Description: N/A or not JCR
    Keywords: QUEST ; Rilievo macrosismico ; INGV ; QUEST-DATA ; Survey ; EMS-98 macroseismic scale ; Danno ; Vulnerabilità ; 04.06. Seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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