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Ducarme, B.
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- PublicationOpen AccessAn overview on wavelet multi-resolution decomposition compared with traditional frequency domain filtering for continuous gravity data denoising(2006)
; ; ; ; ;Panepinto, S.; Royal Observatory of Belgium, Brussels, Belgium ;Greco, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Luzio, D.; Dipartimento di chimica e Fisica della Terra, University of Palermo, Italy ;Ducarme, B.; Royal Observatory of Belgium, Brussels, Belgium ;; ; Continuous gravity recordings in volcanic area could play a fundamental role in the monitoring of active volcanoes and in the prediction of eruptive events too. This geophysical methodology is utilized, on active volcanoes, in order to detect mass changes linked to magma transfer processes and, thus, to recognize forerunners to paroxysmal volcanic events. Spring gravimeters are still the most utilized instruments for microgravity studies because of their relatively low cost and small size, which make them easy to transport and install. Continuous gravity measurements are now increasingly performed at sites very close to active craters, where there is the greatest opportunity to detect significant gravity changes due to a volcanic activity. Unfortunately, spring gravity meters show a strong influence of meteorological parameters (i.e. pressure, temperature and humidity), especially in the adverse environmental conditions usually encountered at such places. As the gravity changes due to the volcanic activity are very small compared to other geophysical or instrumental effects we need a new mathematical tool to get reliable gravity residuals susceptible to reflect the volcanic effect. In the following we present and discuss a preliminary work about the confrontation between the traditional filtering methodology and the Wavelet transform. The overall results show that the performance of the wavelet-based filter seems better than the Fourier one. Moreover, the possibility of getting a multi-resolution analysis and study local features of the signal in the time domain makes the proposed methodology a valuable tool for gravity data processing.208 494 - PublicationRestrictedHigh Precision Tilt Observation at Mt. Etna Volcano, Italy(2011)
; ; ; ; ; ; ;Ferro, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Gambino, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Panepinto, S.; Dipartimento di Chimica e Fisica della Terra ed Applicazioni alle Georisorse e ai Rischi Naturali (CFTA), Università degli Studi di Palermo, Palermo, Italy ;Falzone, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Laudani, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Ducarme, B.; International Center for Earth Tides – Catholic University of Louvain, Georges Lemaître Centre for Earth and Climate Research, Louvain, Belgium; ; ;; ; In 2007-2008, we installed on Mt. Etna two deep tilt stations using high resolution, self-leveling instruments. These installations are a result of accurate instrument tests, site selection, drilling and sensor positioning that has allowed detecting variations related to the principal diurnal and semidiurnal tides for first time on Mt. Etna using tilt data. We analyzed the tidal effects recorded on tilt signals and we removed tidal effects from signals, thereby allowing to detect changes of about 20 nrad with a considerable improvement in respect to the previous installation. Tilt changes have accompanied the Mt. Etna main eruptive phases and are generally related to the rapid rise of magma and formation of dikes and eruptive fissures. However, tilt changes may characterize lava fountains, earthquakes, and inflation-deflation phases. The 2008-2009 eruption represents an example of the potential of the tiltmeters we used, which provides new perspectives for highly precise monitoring of ground deformation on volcanoes.391 23 - PublicationOpen AccessTidal gravity observations at Mt. Etna and Stromboli: results concerning the modeled and observed tidal factors(2008-02)
; ; ; ; ;Panepinto, S.; Università degli Studi di Palermo, Italy ;Greco, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Luzio, D.; Università degli Studi di Palermo, Ital ;Ducarme, B.; Royal Observatory of Belgium, Brussels, Belgium ;; ; Continuous gravity observations performed in the last few years, both at Mt. Etna and Stromboli, have prompted the need to improve the tidal analysis in order to acquire the best corrected data for the detection of volcano related signals. On Mt. Etna, the sites are very close to each other and the expected tidal factor differences are negligible. It is thus useful to unify the tidal analysis results of the different data sets in a unique tidal model. This tidal model, which can be independently confirmed by a modeling of the tidal parameters based on the elastic response of the Earth to tidal forces and the computation of the ocean tides effects on gravity, is very useful for the precise tidal gravity prediction required by absolute or relative discrete gravity measurements. The change in time of the gravimeters’ sensitivity is also an important issue to be checked since it affects not only the results of tidal analysis but also the accuracy of the observed gravity changes. Conversely, if a good tidal model is available, the sensitivity variations can be accurately reconstructed so as to retune observed tidal records with the synthetic tide, since the tidal parameters are assumed to be constant at a given location.229 690