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Currenti, Gilda
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Preferred name
Currenti, Gilda
Email
gilda.currenti@ingv.it
Staff
staff
ORCID
Scopus Author ID
6506592199
Researcher ID
I-3136-2017
92 results
Now showing 1 - 10 of 92
- PublicationOpen AccessReal-time signal processing of high-precision borehole strainmeters atMt. Etna for volcanic surveillance and eruptive events detection(2022-06-23)
; ; ; ; ; ; ; Borehole strainmeter observations at Etna volcano have revealed strain variations associated with volcano activity. In order to automatically identify volcano-related strain changes and track the eruptive activity, we designed the program STRALERT to provide an efficiently filtered strain signal and perform the event detection. By running in near real time, STRALERT contributes to volcanic surveillance operations.377 23 - PublicationOpen AccessDistributed dynamic strain sensing of very long period and long period events on telecom fiber-optic cables at Vulcano, Italy(2023-03-21)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ;; ; ; ; ; ;Volcano-seismic signals can help for volcanic hazard estimation and eruption forecasting. However, the underlying mechanism for their low frequency components is still a matter of debate. Here, we show signatures of dynamic strain records from Distributed Acoustic Sensing in the low frequencies of volcanic signals at Vulcano Island, Italy. Signs of unrest have been observed since September 2021, with CO2 degassing and occurrence of long period and very long period events. We interrogated a fiber-optic telecommunication cable on-shore and off-shore linking Vulcano Island to Sicily. We explore various approaches to automatically detect seismo-volcanic events both adapting conventional algorithms and using machine learning techniques. During one month of acquisition, we found 1488 events with a great variety of waveforms composed of two main frequency bands (from 0.1 to 0.2 Hz and from 3 to 5 Hz) with various relative amplitudes. On the basis of spectral signature and family classification, we propose a model in which gas accumulates in the hydrothermal system and is released through a series of resonating fractures until the surface. Our findings demonstrate that fiber optic telecom cables in association with cutting-edge machine learning algorithms contribute to a better understanding and monitoring of volcanic hydrothermal systems.399 8 - PublicationOpen AccessLa rete dei dilatometri in pozzi profondi dell’Etna.(2015)
; ; ; ;Bonaccorso, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Currenti, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Sicali, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; ; Dopo una lunga fase preparatoria sull’Etna è stata installata una rete composta da 4 dilatometri installati in pozzi profondi. Questa attività è avvenuta in due fasi successive (2010-2011 e 2013) supportate da altrettanti progetti di ricerca. I dilatometri da pozzo sono installati in fori trivellati a profondità solitamente maggiori di 100 m, e misurano lo strain volumetrico a cui è sottoposta la roccia circostante potenzialmente con precisioni nominali fino a 10-12 in un ampio intervallo di frequenze (10-7 – 102 Hz). In questo lavoro sono illustrate le caratteristiche degli apparati utilizzati, le metodologie di installazione in pozzo, e le problematiche della gestione strumentale. Vengono poi descritti i risultati delle calibrazioni strumentali ottenute dopo l’installazione tramite le differenti metodologie. Sono inoltre illustrati i risultati ottenuti dalle variazioni di strain registrate nel breve termine durante le numerose fontane di lava emesse dall’Etna nel periodo2011-2013, e sono anche presentate le variazioni di segnale registrare a tutte le stazioni durante l’ultima fontana di lava del 28 Dicembre 2014. Infine sono anche mostrate le potenzialità del segnale a rilevare nel medio-lungo termine variazioni significative connesse a differenti fasi dell’attività vulcanica. After a long preparatory phase on Etna a network of 4 borehole dilatometers has been installed. This activity took place in two successive phases (2010-2011 and 2013) supported by two research projects. The borehole dilatometers are installed in holes drilled at depths usually greater than 100 m, and they measure the volumetric strain of the surrounding rock potentially with nominal precision up to 10-12 in a wide frequency range (10-7 – 102 Hz). In this paper we describe the characteristics of the equipment used, the methods for the borehole installations, and the problematic related to the instrumental working. We describe the results of the instrumental calibrations obtained by different methods after the installations. We illustrate the results obtained by the changes of strain recorded in the short-term during the several lava fountains emitted from Etna during 2011-2013, and we also show signal changes recorded at all four stations during the last lava fountain of 28 December 2014. Finally, we show the potential of the signal in the medium-term to detected significant changes related to different stages of volcanic activity.413 430 - PublicationOpen AccessPerformance of a Rotational Sensor to Decipher Volcano Seismic Signals on Etna, Italy(2022)
; ; ; ; ; ; ; ; ; ;; ; ; ; ;Volcano-seismic signals such as long-period events and tremor are important indicators for volcanic activity and unrest. However, their wavefield is complex and characterization and location using traditional seismological instrumentation is often difficult. In 2019 we recorded the full seismic wavefield using a newly developed 3C rotational sensor co-located with a 3C traditional seismometer on Etna, Italy. We compare the performance of the rotational sensor, the seismometer and the Istituto Nazionale di Geofisica e Vulcanologia-Osservatorio Etneo (INGV-OE) seismic network with respect to the analysis of complex volcano-seismic signals. We create event catalogs for volcano-tectonic (VT) and long-period (LP) events combining a STA/LTA algorithm and cross-correlations. The event detection based on the rotational sensor is as reliable as the seismometer-based detection. The LP events are dominated by SH-type waves. Derived SH phase velocities range from 500 to 1,000 m/s for LP events and 300–400 m/s for volcanic tremor. SH-waves compose the tremor during weak volcanic activity and SH- and SV-waves during sustained strombolian activity. We derive back azimuths using (a) horizontal rotational components and (b) vertical rotation rate and transverse acceleration. The estimated back azimuths are consistent with the INGV-OE event location for (a) VT events with an epicentral distance larger than 3 km and some closer events, (b) LP events and tremor in the main crater area. Measuring the full wavefield we can reliably analyze the back azimuths, phase velocities and wavefield composition for VT, LP events and tremor in regions that are difficult to access such as volcanoes.325 11 - PublicationRestrictedPiezomagnetic fields due to an inclined rectangular fault in a viscoelastic half-space: an application to the 2002–2003 Etna eruption(2008)
; ; ; ; ;Currenti, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Piombo, A.; Università Bologna ;Del Negro, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Dragoni, M.; Università Bologna; ; ; Time-dependent piezomagnetic fields due to inclined rectangular faults embedded in a viscoelastic, homogeneous half-space were investigated. A viscoelastic rheology of the surrounding medium was assumed to relate piezomagnetic changes at the surface to the stress field at depth. The viscosity of the medium strongly influences time-dependent stress changes. Especially in volcanic areas, rocks near magmatic sources are considerably heated. The presence of higher temperatures produces a lower effective viscosity in the crust, making it necessary to consider its inelastic properties. Rocks no longer behave in a purely elastic manner but permanently deform because the viscosity is significantly lowered. To determine the time-dependent piezomagnetic fields in a viscoelastic medium, we applied the Correspondence Principle to the analytical elastic solutions for dislocation sources. Among all the possible rheological models, we investigated three cases in which the bulk modulus is purely elastic and the shear modulus relaxes as for (i) a Maxwell solid, (ii) a standard linear solid (SLS) and (iii) a Kelvin solid. The piezomagnetic field completely vanishes after the relaxation process for a Maxwell rheology, whereas it is found to decrease over time and reach some finite offset values for SLS and Kelvin rheologies. A real case study concerning the magnetic anomalies observed during the 2002–2003 Mt Etna eruption is also investigated. Post-eruptive magnetic variations were in general agreement with a viscoelastic relaxation process of a SLS rheology undergoing in the volcano edifice.129 17 - PublicationRestrictedInteraction of volcano-tectonic fault with magma storage, intrusion and flank instability: a thirty years study at Mt. Etna volcano(2013)
; ; ; ;Bonaccorso, 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; ; We investigated the relationship between the occurrence of earthquakes along the main volcano-tectonic structures and periods of volcanic unrest at Mt Etna. We focused our study on the Pernicana Fault System (PFS), one of the most outstanding tectonic structures delineating the northern border of the sliding eastern flank of Etna volcano. During recent decades several flank eruptions have occurred at Mt Etna and sometimes PFS released seismicity before the eruptive events, while in other cases there have been earthquakes that did not precede any eruption. To highlight a possible relation between PFS ruptures and volcanic unrest, we took into account the most energetic earthquakes (M ≥ 3.5) occurring in the last three decades (1980-2010), and considered the volcano deformation sources previously inferred by inverting geodetic data recorded during the several flank eruptions in this time interval. The estimates of stress redistribution on the PFS due to different volcano sources, such as the magma storage, the dike intrusions and the sliding eastern flank, were studied by implementing 3D numerical models that also consider the presence of topography and medium heterogeneity. Our results show that the pressurization of an intermediate storage and the traction exerted by the eastern flank sliding contribute to the seismicity along the PFS even without preceding an immediate eruption. Instead, the seismicity along the PFS related to the intrusions inside the northern sector of the volcano would represent a potential early-warning for an impending eruption at Mt Etna.209 35 - PublicationOpen AccessInfluence of permeability on the hydrothermal system at Vulcano Island (Italy): inferences from numerical simulations(2021)
; ; ; ; ; ; ; ; ; Volcano-hydrothermal systems are governed by complex interactions between fluid transport, and geochemical and mechanical processes. Evidence of this close interplay has been testified by distinct spatial and temporal correlations in geochemical and geophysical observations at Vulcano Island (Italy). To understand the interaction between fluid circulation and the geochemical and geophysical manifestations, we perform a parametric study to explore different scenarios by implementing a hydro-geophysical model based on the equations for heat and mass transfer in a porous medium and thermo-poroelastic theory. Numerical simulations allow us to define the controlling role of permeability distribution on the different modeled parameters as well as on the geophysical observables. Changes in the permeability within the highly fractured crater area could be responsible for the fluctuations in gas emission and temperature recorded during the crisis periods, which are accompanied by shallow volcano-seismicity in the absence of significant deformation and gravity variations. Despite the general medium permeability of the volcanic edifice, the presence of more highly permeable pathways, which allow the gas to rapidly escape, as testified by the presence of a well-developed fumarolic field, prevents the pressure buildup at shallow depths.437 12 - PublicationRestrictedElastic model for the gravity and elevation changes before the 2001 eruption of Etna volcano(2007)
; ; ; ;Carbone, D.; 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; ; For 5 months before the 2001 Mt. Etna eruption, a progressive gravity decrease was measured along a profile of stations on the southern slope of the volcano. Between January and July 2001, the amplitude of the change reached 80 μGal, while the wavelength of the anomaly was of the order of 15 km. Elevation changes observed through GPS measurements during a period encompassing the 5-month gravity decrease, remained within 4–6 cm over the entire volcano and within 2–4 cm in the zone covered by the microgravity profile. We review both gravity and elevation changes by a model assuming the formation of new cracks, uniformly distributed in a rectangular prism. The inversion problem was formulated following a global optimization approach based on the use of Genetic Algorithms. Although it is possible to explain the observed gravity changes by means of the proposed analytical formulation, the results show that calculated elevation changes are significantly higher than those observed. Two alternative hypotheses are proposed to account for this apparent discrepancy: (1) that the assumptions behind the analytical formulation, used to invert the data, are fallacious at Etna, and thus, numerical models should be utilized; (2) that a second process, enabling a considerable mass decrease to occur without deformation, acted together with the formation of new cracks in the source volume.163 20 - PublicationOpen AccessFEM and ANN combined approach for predicting pressure source(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.; Università degli Studi di Catania; ; ; ; A hybrid approach for forward and inverse geophysical modeling, based on Artificial Neural Networks (ANN) and Finite Element Method (FEM), is proposed in order to properly identify the parameters of volcanic pressure sources from geophysical observations at ground surface. The neural network is trained and tested with a set of patterns obtained by the solutions of numerical models based on FEM. The geophysical changes caused by magmatic pressure sources were computed developing a 3-D FEM model with the aim to include the effects of topography and medium heterogeneities at Etna volcano. ANNs are used to interpolate the complex non linear relation between geophysical observations and source parameters both for forward and inverse modeling. The results show that the combination of neural networks and FEM is a powerful tool for a straightforward and accurate estimation of source parameters in volcanic regions.141 140 - PublicationOpen AccessEvidence of poro-elastic inflation at the onset of the 2021 Vulcano Island (Italy) unrest(2023-09-27)
; ; ; ; ; ; ; Thermal and pore-pressure variations induced by the circulation of hydrothermal-magmatic fluids in porous and permeable media contribute to ground deformation in volcanic areas. Here, we use solutions for the calculation of the displacements induced by pore-pressure and temperature changes for simplified geometry sources embedded in an elastic half-space with homogeneous mechanical and porous properties. The analytical solution for a spherical source is reviewed, and a semi-analytical approach for the calculation of the displacement for a cylindrical source is presented. Both models were used for the inversion of the daily deformation data recorded on Vulcano Island (Italy) during the 2021 unrest. Starting from September 2021, Vulcano Island experienced an increase in gas emission, seismic activity, and edifice inflation. The deformation pattern evolution from September until mid-October 2021 is indicative of a spatially stationary source. The modeling of the persistent and continuous edifice inflation suggests a deformation source located below the La Fossa crater at a depth of approximately 800 m from the ground surface undergoing a volume change of approximately 105 m3, linked to the rise in fluids from a deeper magmatic source. Corroborated by other sources of geophysical and geochemical evidence, the modeling results support that thermo-poro-elastic processes are sufficient to explain the observed displacement without necessarily invoking the migration of magma to shallow levels. Our findings demonstrate that thermo-poro-elastic solutions may help interpret ground deformation and gain insights into the evolution of the hydrothermal systems, providing useful implications for hazard assessment during volcanic crises.125 20