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  • 1
  • 2
    Publication Date: 2021-04-29
    Description: We study the surface deformation following a moderate size M5+ earthquake sequence that occurred close to Tyrnavos village (Thessaly, Greece) in March 2021. We adopt the interferometric synthetic aperture radar (InSAR) technique to exploit several pairs of Sentinel-1 acquisitions and successfully retrieve the ground movement caused by the three major events (M5+) of the sequence. The mainshocks occurred at depths varying from ~7 to ~10 km, and are related to the activation of at least three normal faults characterizing the area previously unknown. Thanks to the 6-day repeat time of the Sentinel-1 mission, InSAR analysis allowed us to detect both the surface displacement due to the individual analyzed earthquakes and the cumulative displacement caused by the entire seismic sequence. Especially in the case of a seismic sequence that occurs over a very short time span, it is quite uncommon to be able to separate the surface effects ascribable to the mainshock and the major aftershocks because the time frequency of radar satellite acquisitions often hamper the temporal separation of such events. In this work, we present the results obtained through the InSAR data analysis, and are able to isolate single seismic events that were part of the sequence.
    Electronic ISSN: 2076-3263
    Topics: Geosciences
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  • 3
    Publication Date: 2021-05-31
    Description: We study the surface deformation following a moderate size M5+ earthquake sequence that occurred close to Tyrnavos village (Thessaly, Greece) in March 2021. We adopt the interferometric synthetic aperture radar (InSAR) technique to exploit several pairs of Sentinel-1 acquisitions and successfully retrieve the ground movement caused by the three major events (M5+) of the sequence. The mainshocks occurred at depths varying from ~7 to ~10 km, and are related to the activation of at least three normal faults characterizing the area previously unknown. Thanks to the 6-day repeat time of the Sentinel-1 mission, InSAR analysis allowed us to detect both the surface displacement due to the individual analyzed earthquakes and the cumulative displacement caused by the entire seismic sequence. Especially in the case of a seismic sequence that occurs over a very short time span, it is quite uncommon to be able to separate the surface effects ascribable to the mainshock and the major aftershocks because the time frequency of radar satellite acquisitions often hamper the temporal separation of such events. In this work, we present the results obtained through the InSAR data analysis, and are able to isolate single seismic events that were part of the sequence.
    Description: Published
    Description: 191
    Description: 2T. Deformazione crostale attiva
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 4
    Publication Date: 2020-02-27
    Description: In this work, Multi Temporal Interferometry techniques (MTI) based on advanced synthetic aperture radar differential interferometry (A-DInSAR) have been investigated for the monitoring of deformation phenomena in slow kinematics. A-DInSAR methodologies include both Coherence-based type, as well as Small Baseline Subset (SBAS) that Permanent Scatterers (PS). These techniques are capable to provide wide-area coverage and precise, spatially dense information on ground surface deformations. MTI techniques have been applied to the town of Stigliano (MT) in Basilicata Region (Southern Italy), where the social center building has been destroyed after the reactivation of a known landslide. A direct comparison of the results has been shown that PS and SBAS techniques are comparable in terms of obtained coherent areas and displacement patterns, with slightly different velocity values for individual points. In particular, PS furnished a range of velocity between −5/−25 mm/year, while for SBAS we found values around −5/−15 mm/year. Furthermore, on the crown of the landslide body, a Robotics Total Station measuring distance values on 24 points has been installed. The displacement values obtained are in agreement with the results of the MTI analysis, showing as these techniques could be a useful in the case of early-warning situations.
    Description: Published
    Description: 836–852
    Description: 5T. Sismologia, geofisica e geologia per l'ingegneria sismica
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 5
    Publication Date: 2021-12-13
    Description: This paper investigated the achievable accuracy from a low-cost RTK (Real Time Kinematic)/PPK (Post Processing Kinematic) GNSS (Global Navigation Satellite Systems) system installed on board a UAV (Unmanned Aerial Vehicle), employing three different types of GNSS Bases (Alloy, RS2 and RING) working in PPK mode. To evaluate the quality of the results, a set of seven GCPs (Ground Control Points) measured by means of the NRTK (Network Real Time Kinematic) technique was used. The outcomes show a RMSE (Root Mean Square Error) of 0.0189 m for an ALLOY Base, 0.0194 m for an RS2 Base and 0.0511 m for RING Base, respectively, on the vertical value of DEMs (Digital Elevation Models) obtained by a photogrammetric process. This indicates that, when changing the Base for the PPK, the solutions are different, but they can still be considered adequate for precision positioning with UAVs, especially when GCPs could be used with some difficulty. Therefore, the integration of a RTK/PPK GNSS module on a UAV allows the reconstruction of a highly detailed and precise DEM without using GCPs and provides the possibility to carry out surveys in inaccessible areas.
    Description: Published
    Description: 3882
    Description: 1IT. Reti di monitoraggio e sorveglianza
    Description: JCR Journal
    Keywords: GNSS; Multi-Base GNSS; PPK; RTK; UAV; drone; photogrammetry; precision positioning; remote sensing
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 6
    Publication Date: 2022-12-13
    Description: Da venerdì 4 novembre a domenica 6 novembre 2022, si è tenuta una esercitazione nazionale denominata “Exe Sisma dello Stretto 2022” in un'area del territorio della Regione Calabria e della Regione Sicilia caratterizzata da una elevatissima pericolosità sismica. L’esercitazione è stata indetta e coordinata dal Dipartimento della Protezione Civile e aveva l’obiettivo di verificare la risposta operativa a un evento sismico significativo del Servizio Nazionale della Protezione Civile, di cui anche l’Istituto Nazionale di Geofisica e Vulcanologia fa parte. Durante le tre giornate, l’INGV ha avuto modo di testare tutte le procedure che l’Istituto ha codificato a partire da quelle del “Protocollo di Ente per le emergenze sismiche e da maremoto”. Dopo che INGV ha dato l’avvio all’intera esercitazione simulando il terremoto di magnitudo MW 6.2 (ML 6.0) alle ore 09:00 UTC in provincia di Reggio Calabria (5 km a SW dal comune di Laganadi), e ha, quindi, inviato il messaggio per il potenziale maremoto con un livello di allerta arancione; inoltre, il Presidente INGV ha prontamente convocato l’Unità di Crisi e attivato tutti Gruppi Operativi. Questi ultimi, nell’ambito dello scenario esercitativo, hanno verificato che i flussi di comunicazione interna e tutte le attività necessarie in emergenza sismica, presenti nei relativi protocolli operativi, risultassero rispettati. L’obiettivo primario dell’esercitazione è stato quindi quello di validare le attività previste e di aggiornare il personale afferente ai Gruppi Operativi stessi. Tra di essi, SISMIKO, che rappresenta il GO dedicato al coordinamento delle reti sismiche mobili INGV in emergenza, nelle settimane precedenti l’esercitazione ha predisposto tutte le attività che intendeva testare, descrivendole brevemente nel Documento d’impianto INGV e con maggior dettaglio in quello del Gruppo Operativo. A pochi giorni dalla chiusura dell’esercitazione, un terremoto di magnitudo ML 5.7 (MW 5.5) registrato alle ore 06:07 UTC del 09 novembre 2022 ha spostato l’attenzione dalla simulazione alla realtà.
    Description: Istituto Nazionale di Geofisica e Vulcanologia
    Description: Published
    Description: 4T. Sismicità dell'Italia
    Description: 2SR TERREMOTI - Gestione delle emergenze sismiche e da maremoto
    Description: 1IT. Reti di monitoraggio e sorveglianza
    Description: 4IT. Banche dati
    Keywords: SISMIKO ; Esercitazione ; Exercise ; Rischio Sismico Seismic risk ; Seismic risk ; 05.04. Instrumentation and techniques of general interest
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: report
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  • 7
    Publication Date: 2023-06-12
    Description: In this work, we propose a geodetic model for the seismic sequence, with doublet earthquakes, that occurred in Bandar Abbas, Iran, in November 2021. A dataset of Sentinel-1 images, processed using the InSAR (Interferometric Synthetic Aperture Radar) technique, was employed to identify the surface deformation caused by the major events of the sequence and to constrain their geometry and kinematics using seismological constraints. A Coulomb stress transfer analysis was also applied to investigate the sequence’s structural evolution in space and time. A linear inversion of the InSAR data provided a non-uniform distribution of slip over the fault planes. We also performed an accurate relocation of foreshocks and aftershocks recorded by locally established seismographs, thereby allowing us to determine the compressional tectonic stress regime affecting the crustal volume. Despite the very short time span of the sequence, our results clearly suggest that distinct blind structures that were previously unknown or only suspected were the causative faults. The first Mw 6.0 earthquake occurred on an NNE-dipping, intermediate-angle, reverse-oblique plane, while the Mw 6.4 earthquake occurred on almost horizontal or very low-angle (SSE-dipping) reverse segments with top-to-the-south kinematics. The former, which cut through and displaced the Pan-African pre-Palaeozoic basement, indicates a thick-skinned tectonic style, while the latter rupture(s), which occurred within the Palaeozoic–Cenozoic sedimentary succession and likely exploited the stratigraphic mechanical discontinuities, clearly depicts a thin-skinned style.
    Description: Published
    Description: 2981
    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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  • 8
    Publication Date: 2023-10-03
    Description: This study focuses on analyzing and monitoring urban subsidence, particularly in the city of Palermo, Italy. Land subsidence, induced by natural and human factors, poses threats to infrastructure and urban safety. Remote sensing (RS), specifically synthetic-aperture radar interferometry (In-SAR), is employed due to its ability to detect ground displacements over large areas with great precision. The persistent scatterer InSAR (PS-InSAR) technique is utilized to identify stable targets and track millimeter-level surface deformations. This research spans from October 2014 to October 2021, using Sentinel-1 satellite data to capture ground deformation from various angles. The findings are integrated into an accessible web app (ArcGIS) for local authorities that could be used aiding in urban planning and enhancing safety measures. This study’s results offer updated deformation maps, serving as an operational tool to support decision-making and community resilience, emphasizing risk awareness and responsible practices. This study highlights that the exponential expansion of urban areas, which does not take into account historical information, can gravely jeopardize both the integrity of urban infrastructure and the well-being of its inhabitants. In this context, remote sensing technologies emerge as an invaluable ally, used in monitoring and safeguarding the urban landscape.
    Description: Published
    Description: 298
    Description: 5IT. Osservazioni satellitari
    Description: JCR Journal
    Keywords: MT-InSAR; subsidence; urban areas; remote sensing; Palermo; permanent scatterers
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 9
    Publication Date: 2023-10-03
    Description: INGV (National Institute of Geophysics and Volcanology, Italy) is one of the institutions that studies and monitors the geophysical phenomena (earthquakes, volcanic eruptions, landslides, etc.) that occur on Earth. During these events, it is essential to carry out a large, detailed and fast map of the aected areas. If we think of the diculties encountered during the mapping of the fault sources for the 2016 earthquake in central Italy, we can understand how the UAS (Unmanned Aircraft System) can be a valid “low-cost” alternative to the traditional methods of surveys. These devices, thanks to precision instrumentation such as GNSS (Global Navigation Satellite Systems) receivers and IMU (Inertial Measurement Unit) control units, allow a detailed reconstruction of the investigated areas, especially for small-scale analysis applications. These aircraft are based on multiple technologies and show great investigative capabilities, therefore they must be considered as complete systems.Starting from these concepts, we have developed a low-cost RTK/PPK (Real Time Kinematic/Post Processing Kinematic) GNSS survey system on “commercial” UAVs (Unmanned Aerial Vehicles), i.e. professional drones that are not created to be modified. We have demonstrated how the integration of a GNSS RTK/PPK module on commercial UAVs makes the system ecient for the reconstruction of a highly detailed and precise DEM (Digital Elevation Model), without using GCP (Ground Control Point), allowing to make precision measurements in areas that are dicult to explore and investigate. Indeed, the altimetric trends of the PPK processing without GCPs are perfectly comparable with those of the PVs (Verification Points) deriving from RTK analysis and sshow small acceptable deviations. The height dierences between PVs measurements and those deriving from the DEM in the same planar coordinates vary between a minimum of 1 cm and a maximum of 7.8 cm. Based on these results, we can state that the precision mapping with a drone equipped with an on-board GNSS module does not dier much from the technique that involves measuring GCP on the ground, in reality, it is comparable in terms of errors, even on the more dicult field of altitudes.
    Description: Published
    Description: 134-139
    Description: 7TM.Sviluppo e Trasferimento Tecnologico
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 10
    Publication Date: 2022-11-21
    Description: The ML 5.8 earthquake that hit the island of Crete on 27 September 2021 is analysed with InSAR (Interferometry from Synthetic Aperture Radar) and GNSS (Global Navigation Satellite System) data. The purpose of this work is to create a model with sufficient detail for the geophysical processes that take place in several kilometres below the earth’s surface and improve our ability to observe active tectonic processes using geodetic and seismic data. InSAR coseismic displacements maps show negative values along the LOS of ~18 cm for the ascending orbit and ~20 cm for the descending one. Similarly, the GNSS data of three permanent stations were used in PPK (Post Processing Kinematic) mode to (i) estimate the coseismic shifts, highlighting the same range of values as the InSAR, (ii) model the deformation of the ground associated with the main shock, and (iii) validate InSAR results by combining GNSS and InSAR data. This allowed us to constrain the geometric characteristics of the seismogenic fault and the slip distribution on it. Our model, which stands on a joint inversion of the InSAR and GNSS data, highlights a major rupture surface striking 214◦, dipping 50◦ NW and extending at depth from 2.5 km down to 12 km. The kinematics is almost dip-slip normal (rake −106◦), while a maximum slip of ~1.0 m occurred at a depth of ca. 6 km. The crucial though indirect role of inherited tectonic structures affecting the seismogenic crustal volume is also discussed suggesting their influence on the surrounding stress field and their capacity to dynamically merge distinct fault segments.
    Description: Published
    Description: 5783
    Description: 2T. Deformazione crostale attiva
    Description: 3T. Fisica dei terremoti e Sorgente Sismica
    Description: JCR Journal
    Keywords: SAR ; GNSS ; interferometry ; source modelling ; 27 September 2021 earthquake ; Crete system faults ; 04.06. Seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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