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  • 1
    Publication Date: 2017-04-04
    Description: 3-D magneto-elastic models based on finite element method (FEM) have been developed to compute piezomagnetic fields caused by magmatic overpressure sources.We solved separately (i) the elastostatic equation for the stress field and (ii) the coupled Poisson’s equation for magnetic potential field. The numerical computationswere focused on a more realistic modelling of Etna volcano, where remarkable magnetic changes have been observed during eruptive events. We evaluated the effects of topography and medium heterogeneities considering different multilayered crustal structures constrained by seismic tomography and geological evidences. When topography and magneto-elastic heterogeneities are included in the numerical models,the piezomagnetic field changes show significant deviations from the homogeneous half-space solution. Generally, it was found that the analytical model overestimates the expected magnetic changes. The numerical models of the piezomagnetic field showed significant differences in presence of strong magnetization contrasts and in proximity of steep cliffs, that is, at the volcano summit. The FEM approach presented here allows considering a picture of a fully 3-D model of Etna volcano, which could advance the reliability of model-based assessments of magnetic observations.
    Description: Published
    Description: 1469-1476
    Description: 2.6. TTC - Laboratorio di gravimetria, magnetismo ed elettromagnetismo in aree attive
    Description: JCR Journal
    Description: reserved
    Keywords: Numerical solutions ; Magnetic anomalies: modeling and interpretation ; Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
    Publication Date: 2017-04-04
    Description: Long-term and high temporal resolution gravity and deformation data move us toward a better understanding of the behavior of Mt Etna during the June 1995 – December 2011 period in which the volcano exhibited magma charging phases, flank eruptions and summit crater activity. Monthly repeated gravity measurements were coupled with deformation time series using the Differential Synthetic Aperture Radar Interferometry (DInSAR) technique on two sequences of interferograms from ERS/ENVISAT and COSMO-SkyMed satellites. Combining spatiotemporal gravity and DInSAR observations provides the signature of three underlying processes at Etna: (i) magma accumulation in intermediate storage zones, (ii) magmatic intrusions at shallow depth in the South Rift area, and (iii) the seaward sliding of the volcano’s eastern flank. Here we demonstrate the strength of the complementary gravity and DInSAR analysis in discerning among different processes and, thus, in detecting deep magma uprising in months to years before the onset of a new Etna eruption.
    Description: Published
    Description: 3089
    Description: 2V. Dinamiche di unrest e scenari pre-eruttivi
    Description: JCR Journal
    Description: restricted
    Keywords: Microgravity ; Ground deformation ; SAR Interferometry ; Volcano monitoring ; Etna volcano ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 3
    Publication Date: 2020-02-24
    Description: Advances in volcano monitoring and forecasting need a multidisciplinary collaborative framework. In light of this, a Bayesian Event Tree (BET) approach was performed by the application of the BET for Eruption Forecasting (BET_EF) code to analyze the space-time distribution of the volcanic activity of Mount Etna from 2001-2005. First, a reliable monitoring dataset was set up after some sessions to elicit geophysical, volcanological and geochemical ‘precursor’ parameters. A constant unrest probability of 100%, with a magma involvement usually greater than 95%, was computed throughout the time period analyzed. Eruption probabilities higher than 90% were estimated a few days before the onsets of the 2001 and 2002-2003 flank eruptions. Values slightly higher than 75% were observed during the lava fountaining period in June-July 2001. However, the probabilities flattened to around 30% for the 2004-2005 flank eruption. With suitable data, a good depiction of the actual location of the eruptive scenario for the 2001 and 2002-2003 events was provided. Conversely, the size of the eruptions was not indicated.
    Description: Published
    Description: 642-661
    Description: 1.6. Osservazioni di geomagnetismo
    Description: JCR Journal
    Description: open
    Keywords: Volcano monitoring ; Statistical analysis ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 4
    Publication Date: 2020-05-29
    Description: Gravity time sequences collected at Etna volcano by continuously recording spring-based relative gravimeters showed significant variations in temporal correspondence with paroxysmal eruptions. Since the observed gravity variations can only be partially related to subsurface mass redistribution phenomena, we investigated on the instrumental effects due to the ground vibrations as those accompanying explosive activity. We simulated the performances of relative gravimeters through laboratory experiments to estimate their response to vertical and horizontal excitations. Laboratory tests were carried out using a vibrating platform capable of accelerating the instruments with intensities and frequencies, in both the vertical and horizontal directions, observed in the ground vibrations associated with paroxysmal events. The seismic signals recorded at Etna volcano during the 10 April 2011 lava fountain were analyzed to retrieve the parameters used to drive the vibration platform. We tested two gravimeters used for Etna volcano monitoring: the LaCoste & Romberg D#185 and the Scintrex CG-3M#9310234. The experimental results highlight that vibrations, resembling the seismic waves propagated during paroxysmal events, cause an amplitude response in the gravity readings of the order of several hundred of microGals. Generally the relationship between the vibrations and the gravimeter response is non-linear with a fairly complex dependence on the frequencies and amplitude of the signals acting on the gravimeters.
    Description: Published
    Description: 44
    Description: 2V. Dinamiche di unrest e scenari pre-eruttivi
    Description: JCR Journal
    Description: open
    Keywords: Spring-based relative gravimeter ; Vibrating platform ; Volcano monitoring ; Explosive eruptions ; Gravity changes ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 5
    Publication Date: 2017-04-04
    Description: In order to provide a basis for short-term decision- making in the forecasting and monitoring of volcanic activity, we developed an entirely automated system of data acquisition and reduction for magnetic data. The system (Mag-Net) is designed to provide monitoring and analysis of magnetic data on Etna volcano at large distances from the central observatory. The Mag-Net system uses data from an array of continuously recording remote stations spread over the volcanic area and linked by mobile phone to the control center at the local observatory. At this location a computer receives the data and performs data sorting and reduction as well as limited evaluation to detect abnormal behavior or breakdown of remote sensors. Communication software, called Mag- Talk, is also designed to provide data to distant users. With a view to using continuous magnetic observations in advanced analysis techniques for volcano monitoring, the Mag-Net system also delivers two graphical user interface based applications to provide an interpretation capability. The former, called MADAP, speeds up all the data reduction processes in order to evaluate the reliability of magnetic signals. The latter, called VMM, is a procedure for modeling magnetic fields associated with tectonic and volcanic activity to facilitate the identification and interpretation of the sources of a wide spectrum of magnetic signals.
    Description: Published
    Description: 94-99
    Description: 1.6. Osservazioni di geomagnetismo
    Description: JCR Journal
    Description: reserved
    Keywords: Volcano monitoring ; Data-handling system ; Volcanomagnetic modeling ; Mt. Etna ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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