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Del Negro, Ciro
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Del Negro, Ciro
Email
ciro.delnegro@ingv.it
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staff
ORCID
Scopus Author ID
7003335619
Researcher ID
K-3451-2013
141 results
Now showing 1 - 10 of 141
- PublicationOpen AccessABSOLUTE AND RELATIVE GRAVITY MEASUREMENTS AT ETNA VOLCANO (ITALY)(2010-06-22)
; ; ; ; ; ; ; ; ; ; ; ;Greco, Filippo; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Currenti, Gilda; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;D'Agostino, Giancarlo; Istituto Nazionale di Ricerca Metrologica, INRiM, Torino, Italy, ;Del Negro, Ciro; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Di Stefano, Agnese; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Germak, Alessandro; Istituto Nazionale di Ricerca Metrologica, INRiM, Torino, Italy, ;Napoli, Rosalba; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Origlia, Claudio; Istituto Nazionale di Ricerca Metrologica, INRiM, Torino, Italy, ;Pistorio, Antonio; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Scandura, Danila; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Sicali, Antonino; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; ; ; ; ; ; ; ; ; ; ; ; ;Peshekhonov, Vladimir G.; Academician of the RASEmploying both absolute and relative gravimeters, we carried out three hybrid microgravity surveys at Etna volcano between 2007 and 2009. The repeated measurements highlighted the spatio-time evolution of the gravity field associated with the volcanic unrest. We detected a gravity increase attained an amplitude of about 80 µGal on the summit area of the volcano between July 2008 and July 2009. The observed gravity increase could reflect mass accumulations into shallow magma storage system of the volcano located at 1÷2 km below sea level. We present here data and the advantages in using the combined approach of relative and absolute measurements performed at Etna volcano.279 312 - PublicationOpen AccessA Deep Convolutional Neural Network for Detecting Volcanic Thermal Anomalies from Satellite Images(2023)
; ; ; ; ; ; ; The latest generation of high-spatial-resolution satellites produces measurements of high-temperature volcanic features at global scale, which are valuable to monitor volcanic activity. Recent advances in technology and increased computational resources have resulted in an extraordinary amount of monitoring data, which can no longer be so readily examined. Here, we present an automatic detection algorithm based on a deep convolutional neural network (CNN) that uses infrared satellite data to automatically determine the presence of volcanic thermal activity. We exploit the potentiality of the transfer learning technique to retrain a pre-trained SqueezeNet CNN to a new domain. We fine-tune the weights of the network over a new dataset opportunely created with images related to thermal anomalies of different active volcanoes around the world. Furthermore, an ensemble approach is employed to enhance accuracy and robustness when compared to using individual models. We chose a balanced training dataset with two classes, one containing volcanic thermal anomalies (erupting volcanoes) and the other containing no thermal anomalies (non-erupting volcanoes), to differentiate between volcanic scenes with eruptive and non-eruptive activity. We used satellite images acquired in the infrared bands by ESA Sentinel-2 Multispectral Instrument (MSI) and NASA & USGS Landsat 8 Operational Land Imager and Thermal InfraRed Sensor (OLI/TIRS). This deep learning approach makes the model capable of identifying the appearance of a volcanic thermal anomaly in the images belonging to the volcanic domain with an overall accuracy of 98.3%, recognizing the scene with active flows and erupting vents (i.e., eruptive activity) and the volcanoes at rest. This model is generalizable, and has the capability to analyze every image captured by these satellites over volcanoes around the world.89 26 - PublicationRestrictedA second order finite-difference ghost-point method for elasticity problems on unbounded domains with applications to volcanology(2014)
; ; ; ; ;Coco, A.; Bristol University ;Currenti, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Del Negro, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Russo, G.; Università di Catania; ; ; We propose a novel nite-di erence approach for the numerical solution of linear elasticity problems in arbitrary unbounded domains. The method is an extension of a recently proposed ghost-point method for the Poisson equation on bounded domains with arbitrary boundary conditions (Coco, Russo, JCP, 2013) to the case of the Cauchy-Navier equations on unbounded domains. The technique is based on a smooth coordinate transformation, which maps an unbounded domain into a unit square. Arbitrary geometries are de ned by suitable level-set functions. The equations are discretized by classical ninepoint stencil on interior points, while boundary conditions and high order reconstructions are used to de ne the eld variable at ghost-point, which are grid nodes external to the domain with a neighbor inside the domain. The approach is then adopted to solve elasticity problems applied to volcanology for computing the displacement caused by an underground pressure source. The method is suitable to treat problems in which the geometry of the source often changes (explore the e ects of di erent scenarios, or solve inverse problems in which the geometry itself is part of the unknown), since it does not require complex re-meshing when the geometry is modi ed. Several numerical tests are performed, which asses the e ectiveness of the present approach. Keywords: Linear Elasticity, Cauchy-Navier equations, ground deformation, unbounded domain, coordinate transformation method, Cartesian grid, Ghost points, Level-set methods245 46 - PublicationRestrictedEmplacement conditions of the 1256 AD Al-Madinah lava flow field in Harrat Rahat, Kingdom of Saudi Arabia - Insights from surface morphology and lava flow simulations(2016)
; ; ; ; ; ; ; ; ; ; ; ;; ;; ; ;Lava flow hazard modelling requires detailed geological mapping, and a good understanding of emplacement settings and the processes involved in the formation of lava flows. Harrat Rahat, Kingdom of Saudi Arabia, is a large volcanic field, comprising about 1000 predominantly small-volume volcanoes most of which have emitted lava flows of various lengths. A few eruptions took place in this area during the Holocene, and they were located in the northern extreme of the Harrat Rahat, a close proximity to critical infrastructure and population living in Al-Madinah City. In the present study, we combined field work, high resolution digital topography and morphometric analysis to infer the emplacement history of the last historical event in the region represented by the 1256 AD Al-Madinah lava flow field. These datawere also used to simulate 1256 AD-type lava flows in the Harrat Rahat by theMAGFLOWlava flowemplacementmodel,which is able to relate the flowevolution to eruption conditions. The 1256 AD lava flow field extent was mapped at a scale of 1:1000 from a high resolution (0.5 m) Light Detection And Ranging (LiDAR) Digital TerrainModel (DTM), aerial photoswith field support. The bulk volume of the lava flow field was estimated at 0.4 km3, while the source volume represented by seven scoria cone was estimated at 0.023 km3. The lava flow covered an area of 60 km2 and reached a maximum length of 23.4 km. The lava flow field comprises about 20.9% of pāhoehoe, 73.8% of 'a'ā, and 5.3% of late-stage outbreaks. Our field observation, also suggests that the lava flows of the Harrat Rahat region are mainly core-dominated and that they formed large lava flow fields by amalgamation of many single channels. These channels mitigated downslope by topography-lava flow and channel–channel interactions, highlighting this typical process that needs to be considered in the volcanic hazard assessment in the region. A series of numerical lava flow simulations was carried out using a range of water content (0.1–1wt.%), solidification temperature (800–600 °C) and effusion curves (simple and complex curves). These simulations revealed that theMAGFLOW code is sensitive to the changes of water content of the erupting lava magma,while it is less sensitive to solidification temperature and the changes of the shape of effusion curve. The advance rate of the simulated lava flows changed from0.01 to 0.22km/h. Using data and observations from the youngest volcanic event of the Harrat Rahat as input parameters to MAGFLOW code, it is possible to provide quantitative limits on this type of hazard.145 5 - PublicationRestrictedModelling of ground deformation and gravity fields using finite element method: an application to Etna volcano(2007)
; ; ; ;INGV - Sezione Catania ;Currenti, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Del Negro, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Ganci, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; ; Elastic finite element models are applied to investigate the effects of topography and medium heterogeneities on the surface deformation and the gravity field produced by volcanic pressure sources. Changes in the gravity field cannot be interpreted only in terms of gain of mass disregarding the ground deformation of the rocks surrounding the source. Contributions to gravity changes depend also on surface and subsurface mass redistribution driven by dilation of the volcanic source. Both ground deformation and gravity changes were firstly evaluated by solving a coupled axi-symmetric problem to estimate the effects of topography and medium heterogeneities. Numerical results show significant discrepancies in the ground deformation and gravity field compared to those predicted by analytical solutions, which disregard topography, elastic heterogeneities and density subsurface structures. With this in mind, we reviewed the expected gravity changes accompanying the 1993-1997 inflation phase on Mt Etna by setting up a fully 3D finite element model in which we used the real topography, to include the geometry, and seismic tomography, to infer the crustal heterogeneities. The inflation phase was clearly detected by different geodetic techniques (EDM, GPS, SAR and leveling data) that showed a uniform expansion of the overall volcano edifice. When the gravity data are integrated with ground deformation data and a coupled FEM modeling was solved, a mass intrusion could have occurred at depth to justify both ground deformation and gravity observations.121 21 - PublicationOpen AccessRetrospective validation of a lava flow hazard map for Mount Etna volcano(2011)
; ; ; ;Cappello, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Vicari, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Del Negro, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; ; This report presents a retrospective methodology to validate a long-term hazard map related to lava-flow invasion at Mount Etna, the most active volcano in Europe. A lava-flow hazard map provides the probability that a specific point will be affected by potential destructive volcanic processes over the time period considered. We constructed this lava-flow hazard map for Mount Etna volcano through the identification of the emission regions with the highest probabilities of eruptive vents and through characterization of the event types for the numerical simulations and the computation of the eruptive probabilities. Numerical simulations of lavaflow paths were carried out using the MAGFLOW cellular automata model. To validate the methodology developed, a hazard map was built by considering only the eruptions that occurred at Mount Etna before 1981. On the basis of the probability of coverage by lava flows, the map was divided into ten classes, and two fitting scores were calculated to measure the overlap between the hazard classes and the actual shapes of the lava flows that occurred after 1981.484 471 - PublicationOpen AccessApplication of the Wiener filter to magnetic profiling in the volcanic environment of Mt. Etna (Italy)(1996-01)
; ;Del Negro, C.; Istituto Internazionale di Vulcanologia, C.N.R., Catania, ItalyThe frequency-domain Wiener filtering was applied to magnetic anomalies in the volcanic area of Mt. Etna. This filter, under suitable conditions (additive noise, linear processing and mean-square error criterion), can furnish an effective tool for discriminating the geologic feature of interest (the signal) from the noise. The filter was first tested with synthetic data. Afterwards it was applied to a magnetic profile carried out across the principal fault system of the Mt. Etna volcano, that hosted the dykes feeding both the 1989 and the 1991-93 eruptions. The magnetic anomalies linked to the volcanic section and those linked to the contact between the clay basement and the lava coverage show significant spectral overlap. Thus by estimating the power spectrum of the signal, obtained resolving the forward problem, a least-squares Wiener filter has been designed. In such context, it was possible to verify the effectiveness of Wiener filters, whereas traditional band-pass filtering proved inadequate. In fact, analysis of the noise showed that all the meaningful components of the observed magnetic field were resolved. The results put further constraints on location and geometry of the shallow plumbing system of Mt. Etna.274 205 - PublicationRestrictedA year of lava fountaining at Etna: Volumes from SEVIRI(2012-03)
; ; ; ; ; ; ; ; ;Ganci, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Harris, A. J. L. ;Del Negro, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Guehenneux, Y. ;Cappello, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Labazuy, P. ;Calvari, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Gouhier, M.; ;; ;; ;; We present a new method that uses cooling curves, apparent in high temporal resolution thermal data acquired by geostationary sensors, to estimate erupted volumes and mean output rates during short lava fountaining events. The 15 minute temporal resolution of the data allows phases of waxing and peak activity to be identified during short (150-to- 810 minute-long) events. Cooling curves, which decay over 8-to-21 hour-periods following the fountaining event, can also be identified. Application to 19 fountaining events recorded at Etna by MSG’s SEVIRI sensor between 10 January 2011 and 9 January 2012, yields a total erupted dense rock lava volume of 28 106 m3, with a maximum intensity of 227 m3 s 1 being obtained for the 12 August 2011 event. The timeaveraged output over the year was 0.9 m3 s 1, this being the same as the rate that has characterized Etna’s effusive activity for the last 40 years.170 24 - PublicationOpen Access4D Hybrid Microgravity Measurements: Two Case Studies of Monitoring at Mt. Etna Volcano and at a Gas Storage Reservoir in Northern Italy(2011)
; ; ; ; ; ; ;Greco, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Pistorio, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Currenti, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Del Negro, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Napoli, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Scandura, D.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; ; ; ; ; Detection of clear gravity signals associated with the renewal of the volcanic activity and the emerging need of characterizing the dynamic changes of subsurface systems have led to increased application of the microgravity method in time-lapsed monitoring, also known as 4D gravity approach. Conventionally, microgravity measurements have been carried out using relative gravimeters, which measure spatial changes with respect to a fixed reference site. Since 2007, with the aim of comparing relative microgravity measurements routinely acquired on Etna with absolute gravity observations, we performed repeated surveys using transportable absolute gravimeters.491 1752 - PublicationRestrictedIntegrated inversion of numerical geophysical models using artificial neural networks(2010)
; ; ; ; ; ;Di Stefano, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Currenti, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Del Negro, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Fortuna, L.; Università degli studi di Catania ;Nunnari, G.; Dike deflection modelling for inferring magma pressure and withdrawal,; ; ; ; A uni ed modelling procedure is proposed to jointly interpret the variations observed in geophysical data and to properly take into account the relation- ship between the intrusive processes and the geophysical variations expected at the ground surface. We focus on the joint inversion of geophysical data by a procedure based on Arti cial Neural Network (ANN) for the estimation of the volcanic source parameters. As forward model, we develop a 3D numerical model based on Finite Element Method (FEM) for computing ground deforma- tion, magnetic and gravity changes caused by magmatic overpressure sources, with the aim to consider a more realistic description of Etna volcano, including the e ects of topography and medium heterogeneities.151 27