31 research outputs found
Gestione dei dilatometri installati in pozzi profondi allâEtna
La rivista non prevede l'Abstract e inizia direttamente dall'Introduzione, che viene sotto riportata.
In ambiente vulcanico, al fine di monitorare e studiare lâazione delle sorgenti, è di fondamentale importanza riuscire a misurare con estrema precisione lâespansione/contrazione del mezzo. Questo è ottenibile attraverso lâutilizzo di strumenti noti come borehole strainmeters (o dilatometri da pozzo). Lo strumento di base e' da un punto di vista teorico abbastanza semplice. Consiste di un tubo cilindrico, al suo interno riempito di specifico fluido (solitamente olio di silicone), da installare in un foro appositamente trivellato ponendolo in contatto con le pareti rocciose del foro attraverso lâutilizzo di cementi ad espansione, che consentono un perfetto accoppiamento strumento-mezzo. La variazione di livello del fluido indotta dalla variazione dello strain nel mezzo circostante è quindi misurata con estrema precisione attraverso un apposito sensore. I dilatometri da pozzo sono gli strumenti piĂš sensibili alle variazioni dello stato degli sforzi finora realizzati a fini geofisici (sensibilitĂ nominale dV/V fino a 10-12). La tipologia di strumentazione utilizzata nelle installazioni allâEtna è quella nota come Sacks-Evertson borehole strainmeters (o dilatometers) [Sacks et al., 1971]. Le principali caratteristiche tecniche della strumentazione sono riportate in tabella 1. Gli strainmeters e lâelettronica di controllo sono prodotti dal Department Terrestrial Magnetism (DTM) del Carnegie Institution di Washington. I colleghi del DTM sono presenti alle fasi finali dâinstallazione e di avvio dellâoperativitĂ strumentale
Multidisciplinary geophysical study of the NE sector of the unstable flank of Etna volcano
On volcanic areas, usually characterized by complex structural environments, a lot of independent geophysical
studies are usually performed. The non-uniqueness of the geophysical inverse models, the different level of reso-
lution and sensitivity of the results spurred us to integrate independent geophysical datasets and results collected
on Mt. Etna volcano, in order to obtain more accurate and reliable model interpretation.
Mt. Etna volcano is located along the eastern coast of Sicily and it is characterized by a complex structural set-
ting. In this region, the general N-S compressive regime related to the Africa â Europe collision interacts with the
WNW-ESE extensional regime associated to the Malta Escarpment dynamics, observable along the eastern coast
of Sicily.
At Mt Etna, a great number of studies concerns the existence of instability phenomena; a general eastward mo-
tion of the eastern ďŹank of the volcano has been measured with always increasing detail and its relationship with
the eruptive and magmatic activity is being investigated. The unstable ďŹank appears bounded to the north by the
EâW-trending Provenzana - Pernicana Fault System and to the SW by the NS Ragalna Fault system. Eastwards,
this area is divided by several NWâSE trending faults. Recent studies consider this area as divided into several
blocks characterized by different shape and kinematics. Ground deformation studies (GPS and InSAR) deďŹne the
NE portion of the unstable ďŹank as the most mobile one.
In the frame of the MEDiterranean Supersites Volcanoes (MED-SUV) project, ground deformation data (GPS and
INSAR), 3D seismicity, seismic tomography and two resistivity model proďŹles, have been analyzed together, in
order to put some constraints on the deep structure of the NE sector of the unstable ďŹank.
Seismic data come from the permanent network run by the Istituto Nazionale di GeoďŹsica e Vulcanologia (INGV)
- Sezione di Catania, Osservatorio Etneo.
Ground deformation data comes from InSAR Permanent Scatterers analyses of different spaceborn sensors.
The resistivity models come from a MT survey carried out on the eastern ďŹank of the volcano and consisting of
thirty broad-band soundings along N-S and NW-SE oriented proďŹles.
We found that the NE sector of the sliding volume, modeled by ground deformation data inversions and character-
ized by the highest displacement velocity, is characterized low resistivity values and it is bounded by two seismic
clusters. The northern one is clearly related to the Pernicana fault and itâs not deeper than 3 km b.s.l. while the
second one is located southwards, beneath the northern wall of the Valle del Bove, not related to any evident struc-
ture at the surface. An evident layer with very reduced seismicity lies at 3 km of depth and well corresponds to the
simpliďŹed analytic models of a sliding planar surface resulting from GPS data inversions
Seismic-induced accelerations detected by two parallel gravity meters in continuous recording with a high sampling rate at Etna volcano
We analyse a microgravity data set acquired from two spring LaCoste & Romberg gravity meters operated in parallel at the same site on Etna volcano (Italy) for about two months (August â September 2005). The high sampling rate acquisition (2Hz) allowed the correlation of short-lasting gravity fluctuations with seismic events. After characterizing the oscillation behavior of the meters, through the study of spectral content and the background noise level of both sequences, we recognized fluctuations in the gravity data, spanning a range of periods from 1 second to about 30 seconds dominated by components with a period of about 15 á 25 seconds, during time intervals encompassing both local seismic events and large worldwide earthquakes. The data analyses demonstrate that observed earthquake-induced gravity fluctuations have some differences due to diverse spectral content of the earthquakes. When local seismic events which present high frequency content excite the meters, the correlation between the two gravity signals is poor (factor < 0.3). Vice versa, when large worldwide earthquakes occur and low frequency seismic waves dominate the ensuing seismic wavefield, the resonance frequencies of the meters are excited and they react according to more common features. In the latter case, the signals from the two instruments are strongly correlated to each other (up to 0.9). In this paper the behaviors of spring gravimeters in the frequency range of the disturbances produced by local and large worldwide earthquakes are presented and discussed
Experimentation of two coupled gravity meters in continuous recording with a high sampling rate at Etna volcano
During the summer of 2005, we performed a 2-month lasting experiment (29 July - 29 September), using two spring gravimeters installed side-by-side at Mt. Etna. Two LaCoste & Romberg gravimeters were utilized (G594 and G1190), each equipped with an Aliod 100 electronic feedback system. Data were acquired at a sampling rate (2 Hz) higher than that normally used for gravimetric recordings.
Apparent fluctuations (i.e. instrumental, not due to actual changes of the gravity field) dominated by a component with period of about 20 seconds appear over the gravity recordings when both high-frequency (local earthquakes) and low-frequency (teleseisms) components dominate the ensuing seismic wavefield.
Though it has only an instrumental character, the outcome of this study represent an important further step towards the development of any a-priori or a-posteriori system aimed at reduce the effect of seismic shocks on the signal from continuously recording gravimeters
TOMO-ETNA experiment at Etna volcano: Activities on land
In the present paper we describe the on-land field operations integrated in
the TOMO-ETNA experiment carried out in June-November 2014 at Mt.
Etna volcano and surrounding areas. This terrestrial campaign consists
in the deployment of 90 short-period portable three-component seismic
stations, 17 broadband seismometers and the coordination with 133 permanent
seismic station belonging to Italyâs Istituto Nazionale di Geofisica
e Vulcanologia (INGV). This temporary seismic network recorded active
and passive seismic sources. Active seismic sources were generated
by an array of air-guns mounted in the Spanish oceanographic vessel
âSarmiento de Gamboaâ with a power capacity of up to 5200 cubic
inches. In total more than 26,000 shots were fired and more than 450 local
and regional earthquakes were recorded. We describe the whole technical
procedure followed to guarantee the success of this complex seismic experiment.
We started with the description of the location of the potential
safety places to deploy the portable network and the products derived from
this search (a large document including full characterization of the sites,
owners and indication of how to arrive to them). A full technical description
of the seismometers and seismic sources is presented. We show
how the portable seismic network was deployed, maintained and recovered
in different stages. The large international collaboration of this experiment
is reflected in the participation of more than 75 researchers,
technicians and students from different institutions and countries in the
on-land activities. The main objectives of the experiment were achieved
with great success.PublishedS04272SR. VULCANI - Servizi e ricerca per la SocietĂ JCR Journalope
A case study of cascade supercritical CO2 power cycle for waste heat recovery from a small gas turbine
Gestione dei dilatometri installati in pozzi profondi allâEtna
La rivista non prevede l'Abstract e inizia direttamente dall'Introduzione, che viene sotto riportata.
In ambiente vulcanico, al fine di monitorare e studiare lâazione delle sorgenti, è di fondamentale importanza riuscire a misurare con estrema precisione lâespansione/contrazione del mezzo. Questo è ottenibile attraverso lâutilizzo di strumenti noti come borehole strainmeters (o dilatometri da pozzo). Lo strumento di base e' da un punto di vista teorico abbastanza semplice. Consiste di un tubo cilindrico, al suo interno riempito di specifico fluido (solitamente olio di silicone), da installare in un foro appositamente trivellato ponendolo in contatto con le pareti rocciose del foro attraverso lâutilizzo di cementi ad espansione, che consentono un perfetto accoppiamento strumento-mezzo. La variazione di livello del fluido indotta dalla variazione dello strain nel mezzo circostante è quindi misurata con estrema precisione attraverso un apposito sensore. I dilatometri da pozzo sono gli strumenti piĂš sensibili alle variazioni dello stato degli sforzi finora realizzati a fini geofisici (sensibilitĂ nominale dV/V fino a 10-12). La tipologia di strumentazione utilizzata nelle installazioni allâEtna è quella nota come Sacks-Evertson borehole strainmeters (o dilatometers) [Sacks et al., 1971]. Le principali caratteristiche tecniche della strumentazione sono riportate in tabella 1. Gli strainmeters e lâelettronica di controllo sono prodotti dal Department Terrestrial Magnetism (DTM) del Carnegie Institution di Washington. I colleghi del DTM sono presenti alle fasi finali dâinstallazione e di avvio dellâoperativitĂ strumentale.Published1-255V. Sorveglianza vulcanica ed emergenzeN/A or not JCRope
The borehole dilatometers network of Etna.
Dopo una lunga fase preparatoria sullâEtna 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 profonditĂ 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 â 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 lâinstallazione 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 dallâEtna nel periodo2011-2013, e sono anche presentate le variazioni di segnale registrare a tutte le stazioni durante lâultima fontana di lava del 28 Dicembre 2014. Infine sono anche mostrate le potenzialitĂ del segnale a rilevare nel medio-lungo termine variazioni significative connesse a differenti fasi dellâattivitĂ 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 â 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.Published1-322V. Dinamiche di unrest e scenari pre-eruttiviN/A or not JCRope
The borehole dilatometers network of Etna.
Dopo una lunga fase preparatoria sullâEtna 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 profonditĂ 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 â 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 lâinstallazione 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 dallâEtna nel periodo2011-2013, e sono anche presentate le variazioni di segnale registrare a tutte le stazioni durante lâultima fontana di lava del 28 Dicembre 2014. Infine sono anche mostrate le potenzialitĂ del segnale a rilevare nel medio-lungo termine variazioni significative connesse a differenti fasi dellâattivitĂ 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 â 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
Automated system for magnetic monitoring of active volcanoes
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