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  • 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology  (7)
  • 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
  • Wiley  (5)
  • Wiley-Blackwell  (4)
  • Blackwell Publishing  (2)
  • AMER GEOPHYSICAL UNION
  • 2015-2019  (1)
  • 2010-2014  (11)
Collection
Years
  • 2015-2019  (1)
  • 2010-2014  (11)
Year
  • 1
    Publication Date: 2021-01-07
    Description: The elemental fluxes and heat flow associated with large aquifer systems can be significant both at local and at regional scales. In fact, large amounts of heat transported by regional groundwater flow can affect the subsurface thermal regime, and the amount of matter discharged towards the surface by large spring systems can be significant relative to the elemental fluxes of surface waters. The Narni-Amelia regional aquifer system (Central Italy) discharges more than 13 m3 sec)1 of groundwater characterised by a slight thermal anomaly, high salinity and high pCO2. During circulation in the regional aquifer, groundwater reacts with the host rocks (dolostones, limestones and evaporites) and mixes with deep CO2-rich fluids of mantle origin. These processes transfer large amounts of dissolved substances, in particular carbon dioxide, and a considerable amount of heat towards the surface. Because practically all the water circulating in the Narni-Amelia system is discharged by few large springs (Stifone-Montoro), the mass and energy balance of these springs can give a good estimation of the mass and heat transported from the entire system towards the surface. By means of a detailed mass and balance of the aquifer and considering the soil CO2 fluxes measured from the main gas emission of the region, we computed a total CO2 discharge of about 7.8 · 109 mol a)1 for the whole Narni-Amelia system. Finally, considering the enthalpy difference between infiltrating water and water discharged by the springs, we computed an advective heat transfer related to groundwater flow of 410 ± 50 MW.
    Description: Published
    Description: 182-196
    Description: 2.4. TTC - Laboratori di geochimica dei fluidi
    Description: 4.5. Studi sul degassamento naturale e sui gas petroliferi
    Description: JCR Journal
    Description: reserved
    Keywords: carbon dioxide degassing ; heat flow ; regional aquifer ; 04. Solid Earth::04.02. Exploration geophysics::04.02.01. Geochemical exploration ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
    Publication Date: 2017-04-04
    Description: Stress can undergo rapid temporal changes in volcanic environments, and this is particularly true during eruptions. We use two independent methods, coda wave interferometry (CWI) and shear wave splitting (SWS) analysis to track stress related wave propagation effects during the waning phase of the 2002 NE fissure eruption at Mt Etna. CWI is used to estimate temporal changes in seismic wave velocity, while SWS is employed to monitor changes in elastic anisotropy. We analyse seismic doublets, detecting temporal changes both in wave velocities and anisotropy, consistent with observed eruptive activity. In particular, syn-eruptive wave propagation changes indicate a depressurization of the system, heralding the termination of the eruption, which occurs three days later.
    Description: Published
    Description: 1779-1788
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Interferometry ; Seismic anisotropy ; Volcano seismology ; Volcano monitoring ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 3
    Publication Date: 2017-04-04
    Description: We have investigated thewavefield properties of the seismic signals generated by the explosions of Volc´an de Colima (M´exico). We have analysed these properties to understand the initial mechanism that triggered the explosive events. Our study is focused on the direct waves coming from the crater area. Thus, we have analysed a set of moderate volcanic explosions at Volc´an de Colima that was recorded by a small aperture seismic array over two periods: October 2005 and April 2006. We can distinguish two types of explosions, Vulcanian and ash-free events. Both types of explosions share the same characteristics, that is a long-period signal (not related to any type of emission) before the arrival of high frequency phases, and a later high frequency signal directly related to ash or gas emission. We have applied the Zero Lag Cross Correlation technique to obtain backazimuth and apparent slowness of the incoming waves. We have also applied polarization analysis to the record of every detected volcanic explosion. By comparing the results of both of these analyses, we have been able to identify the dominant wave types that comprise the seismic wavefield and infer in time and space a possible primary source mechanism that would trigger the volcanic explosions. We have observed an apparent slowness variation of the first onset of the long-period (LP) signal with a possible upward migration of the source; the depth of the source has been identified at a range between 2.6 and 3.3 km below the crater, associated with the range of measured apparent velocities relative to the first onset of the LP signal.
    Description: Published
    Description: 1383–1398
    Description: 3.1. Fisica dei terremoti
    Description: JCR Journal
    Description: reserved
    Keywords: Explosive volcanism; ; Volcano monitoring. ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 4
    Publication Date: 2017-04-04
    Description: A series of computer microtomography experiments are reported which were performed by using a third-generation synchrotron radiation source on volcanic rocks from various active hazardous volcanoes in Italy and other volcanic areas in the world. The applied technique allowed the internal structure of the investigated material to be accurately imaged at the micrometer scale and three-dimensional views of the investigated samples to be produced as well as three-dimensional quantitative measurements of textural features. Thegeometryof thevesicle (gas-filledvoid) network in volcanic products of both basaltic and trachytic compositions were particularly focused on, as vesicle textures are directly linked to the dynamics of volcano degassing. This investigation provided novel insights into modes of gas exsolution, transport and loss in magmas that were not recognized in previous studies using solely conventional two- dimensional imaging techniques. The results of this study are important to understanding the behaviour of volcanoes and can be combined with other geosciences disciplines to forecast their future activity.
    Description: In press
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: JCR Journal
    Description: reserved
    Keywords: high-resolution three-dimensional imaging ; X-ray computed microtomography ; volcanic eruptions ; volcanic rock textures ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 5
    Publication Date: 2017-04-04
    Description: During the early stages of the 2004–2008 Mount St. Helens eruption, the source process that produced a sustained sequence of repetitive long-period (LP) seismic events also produced impulsive broadband infrasonic signals in the atmosphere. To assess whether the signals could be generated simply by seismic-acoustic coupling from the shallow LP events, we perform finite difference simulation of the seismo-acoustic wavefield using a single numerical scheme for the elastic ground and atmosphere. The effects of topography, velocity structure, wind, and source configuration are considered. The simulations show that a shallow source buried in a homogeneous elastic solid produces a complex wave train in the atmosphere consisting of P/SV and Rayleigh wave energy converted locally along the propagation path, and acoustic energy originating from the source epicenter. Although the horizontal acoustic velocity of the latter is consistent with our data, the modeled amplitude ratios of pressure to vertical seismic velocity are too low in comparison with observations, and the characteristic differences in seismic and acoustic waveforms and spectra cannot be reproduced from a common point source. The observations therefore require a more complex source process in which the infrasonic signals are a record of only the broadband pressure excitation mechanism of the seismic LP events. The observations and numerical results can be explained by a model involving the repeated rapid pressure loss from a hydrothermal crack by venting into a shallow layer of loosely consolidated, highly permeable material. Heating by magmatic activity causes pressure to rise, periodically reaching the pressure threshold for rupture of the ‘‘valve’’ sealing the crack. Sudden opening of the valve generates the broadband infrasonic signal and simultaneously triggers the collapse of the crack, initiating resonance of the remaining fluid. Subtle waveform and amplitude variability of the infrasonic signals as recorded at an array 13.4 km to the NW of the volcano are attributed primarily to atmospheric boundary layer propagation effects, superimposed upon amplitude changes at the source.
    Description: Published
    Description: B04305
    Description: JCR Journal
    Description: reserved
    Keywords: infrasound ; events ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 6
    Publication Date: 2017-04-04
    Description: We present the first application of a time reverse location method in a volcanic setting, for a family of long-period (LP) events recorded on Mt Etna. Results are compared with locations determined using a full moment tensor grid search inversion and cross-correlation method. From 2008 June 18 to July 3, 50 broad-band seismic stations were deployed on Mt Etna, Italy, in close proximity to the summit. Two families of LP events were detected with dominant spectral peaks around 0.9 Hz. The large number of stations close to the summit allowed us to locate all events in both families using a time reversal location method. The method involves taking the seismic signal, reversing it in time, and using it as a seismic source in a numerical seismic wave simulator where the reversed signals propagate through the numerical model, interfere constructively and destructively, and focus on the original source location. The source location is the computational cell with the largest displacement magnitude at the time of maximum energy current density inside the grid. Before we located the two LP families we first applied the method to two synthetic data sets and found a good fit between the time reverse location and true synthetic location for a known velocity model. The time reverse location results of the two families show a shallow seismic region close to the summit in agreement with the locations using a moment tensor full waveform inversion method and a cross-correlation location method.
    Description: Published
    Description: 452-462
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Volcano seismology ; Computational seismology ; Wave propagation ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 7
    Publication Date: 2017-04-04
    Description: In this work, we present regional maps of the inverse intrinsic quality factor (Qi −1), the inverse scattering quality factor (Qs −1) and total inverse quality factor (Qt −1) for the volcanic environment of Deception Island (Antarctica). Our attenuation study is based on diffusion approximation, which permits us to obtain the attenuation coefficients for every single couple source-receiver separately. The data set used in this research is derived from an active seismic experiment using more than 5200 offshore shots (air guns) recorded at 32 onshore seismic stations and four ocean bottom seismometers. To arrive at a regional distribution of these values, we used a new mapping technique based on a Gaussian space probability function. This approach led us to create ‘2-D probabilistic maps’ of values of intrinsic and scattering seismic attenuation. The 2-D tomographic images confirm the existence of a high attenuation body below an inner bay of Deception Island. This structure, previously observed in 2-D and 3-D velocity tomography of the region, is associated with a massive magma reservoir. Magnetotelluric studies reach a similar interpretation of this strong anomaly. Additionally, we observed areas with lower attenuation effects that bear correlation with consolidated structures described in other studies and associated with the crystalline basement of the area. Our calculations of the transport mean-free path and absorption length for intrinsic attenuation gave respective values of ≈950 m and 5 km, which are lower than the values obtained in tectonic regions or volcanic areas such as Tenerife Island. However, as observed in other volcanic regions, our results indicate that scattering effects dominate strongly over the intrinsic attenuation.
    Description: This work has been partially supported by the Spanish project Ephestos, CGL2011–29499-C02–01, by the EU project EC-FP7 MEDiterranean SUpersite Volcanoes (MED-SUV), by the Basque Government researcher training program BFI09.277 and by the Regional project ‘Grupo de Investigaci´on en Geof´ısica y Sismolog´ıa de la Junta de Andaluc´ıa, RNM104.’ Edoardo del Pezzo was partly supported by DPC-INGV projects UNREST SPEED and V2 (Precursori).
    Description: Published
    Description: 1957-1969
    Description: 3.1. Fisica dei terremoti
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: restricted
    Keywords: Seismic attenuation; ; Seismic tomography ; Volcano seismology ; Wave scattering and diffraction ; Wave propagation ; 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 8
    Publication Date: 2017-04-04
    Description: The peculiar source characteristics of long-period seismic events (time persistency of the source, low-frequency peaks in the source spectrum, absence of high-frequency radiation) prevent the formation of a definite high-frequency coda in the seismograms. In contrast, this is well formed in volcano–tectonic quakes. For this reason, the widely used duration magnitude scale that is based on the proportionality between the energy and the coda duration cannot be used for long-period estimation. In observatory practice, the long-period magnitude is sometimes estimated using the same duration magnitude scale, leading to confusing results. In this report, we show a new method to estimate the magnitude of long-period events that generally occur for volcanoes, with some application examples from data for Mt Etna (Italy), Colima Volcano (Mexico) and Campi Flegrei (Italy).
    Description: Published
    Description: 911-919
    Description: 3.1. Fisica dei terremoti
    Description: JCR Journal
    Description: restricted
    Keywords: Earthquake source observations; ; Volcano monitoring ; Volcano seismology ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 9
    Publication Date: 2017-04-04
    Description: Different procedures were used to analyze a comprehensive time series of nighttime thermal infrared images acquired from October 2006 to June 2013 by a permanent station at Pisciarelli (Campi Flegrei, Italy). The methodologies were aimed at the detection and quantification of possible spatiotemporal changes in the ground-surface thermal features of an area affected by diffuse degassing. Long-term infrared time series images were processed without taking into account atmospheric conditions and emissivity estimations. The data obtained were compared with the trends of independent geophysical and geochemical parameters, which suggested that long-term temporal variations of the surface maximum temperatures were governed by the dynamics of the deeper hydrothermal system. Analogously, the dynamics of the shallow hydrothermal system are likely to control the short-period thermal oscillations that overlie the long-term thermal signals. The map of the yearly rates of temperature change shows temperature increases clustered in the thermal anomalous area of the infrared images, without evidence of modifications to the extension of the anomaly or of growth of new areas with significant thermal emission. This suggests that in the present state, the heat transfer is mainly due to hot gas emission through preexisting fractures and vents. Our data indicate that the comprehensive picture of the spatiotemporal evolution of the thermal features of the hydrothermal sites obtained by long-term infrared monitoring can provide useful information toward refining physical and conceptual models, as well as improving surveillance of active volcanoes.
    Description: The TIR monitoring system was partially funded by the 2000–2006 National Operating Programme and by the Italian Civil Protection Department in the framework of the 2004–2006 agreement with the Istituto Nazionale di Geofisica e Vulcanologia.
    Description: Published
    Description: 812–826
    Description: 2V. Dinamiche di unrest e scenari pre-eruttivi
    Description: 5V. Sorveglianza vulcanica ed emergenze
    Description: JCR Journal
    Description: restricted
    Keywords: Thermal Infrared Monitoring ; Campi Flegrei ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 10
    Publication Date: 2017-04-04
    Description: The complex volcanic system of Tenerife Island is known to have a highly heterogeneous character, as recently confirmed by velocity tomography.We present new information derived from intrinsic quality factor inverse maps (Qi −1), scattering quality factor inverse maps (Qs −1) and total quality factor inverse maps (Qt −1) obtained for the same region. The data set used in this work is the result of the analysis of an active seismic experiment carried out, using offshore shots (air guns) recorded at over 85 onshore seismic stations. The estimates of the attenuation parameters are based on the assumption that the seismogram energy envelopes are determined by seismic energy diffusion processes occurring inside the island. Diffusion model parameters, proportional to Qi −1 and to Qs −1, are estimated from the inversion of the energy envelopes for any source–receiver couple. They are then weighted with a new graphical approach based on a Gaussian space probability function, which allowed us to create ‘2-D probabilistic maps’ representing the space distribution of the attenuation parameters. The 2-D images obtained reveal the existence of a zone in the centre of the island characterized by the lowest attenuation effects. This effect is interpreted as highly rigid and cooled rocks. This low-attenuation region is bordered by zones of high attenuation, associated with the recent historical volcanic activity. We calculate the transport mean free path obtaining a value of around 4 km for the frequency range 6–12 Hz. This result is two orders of magnitude smaller than values calculated for the crust of the Earth. An absorption length between 10 and 14 km is associated with the average intrinsic attenuation parameter. These values, while small in the context of tectonic regions, are greater than those obtained in volcanic regions such as Vesuvius or Merapi. Such differences may be explained by the magnitude of the region of study, over three times larger than the aforementioned study areas. This also implies deeper sampling of the crust, which is evidenced by a change in the values of seismic attenuation. One important observation is that scattering attenuation dominates over the intrinsic effects, Qi being at least twice the value of Qs.
    Description: This work has been partially supported by the Spanish project Ephestos, CGL2011-29499-C02-01, by the EU project EC-FP7 MEDiterranean SUpersite Volcanoes (MED-SUV), by the Basque Government researcher training program BFI09.277 and by the Regional project ‘Grupo de Investigaci´on en Geof´ısica y Sismolog´ıa de la Junta de Andaluc´ıa, RNM104’. EdP has been partly supported by DPC-INGV projects UNREST SPEED and V2 (Precursori).
    Description: Published
    Description: 1942-1956
    Description: 3.1. Fisica dei terremoti
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: restricted
    Keywords: Seismic attenuation ; ; Seismic tomography; ; Volcano seismology ; Wave propagation. ; 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 11
    Publication Date: 2017-04-04
    Description: We present the first application of a time reverse location method in a volcanic setting, for a family of long-period (LP) events recorded on Mt Etna. Results are compared with locations determined using a full moment tensor grid search inversion and cross-correlation method. From 2008 June 18 to July 3, 50 broad-band seismic stations were deployed on Mt Etna, Italy, in close proximity to the summit. Two families of LP events were detected with dominant spectral peaks around 0.9 Hz. The large number of stations close to the summit allowed us to locate all events in both families using a time reversal location method. The method involves taking the seismic signal, reversing it in time, and using it as a seismic source in a numerical seismic wave simulator where the reversed signals propagate through the numerical model, interfere constructively and destructively, and focus on the original source location. The source location is the computational cell with the largest displacement magnitude at the time of maximum energy current density inside the grid. Before we located the two LP families we first applied the method to two synthetic data sets and found a good fit between the time reverse location and true synthetic location for a known velocity model. The time reverse location results of the two families show a shallow seismic region close to the summit in agreement with the locations using a moment tensor full waveform inversion method and a cross-correlation location method.
    Description: In press
    Description: (11)
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Volcano seismology ; Computational seismology ; Wave propagation ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 12
    Publication Date: 2017-04-04
    Description: We study the possibility of muon radiography as a tool to investigate space and time changes in the internal density distribution inside geological structures. Previous work has shown the practical applicability of this method. Nevertheless, quantitative information on factors which impose limitations on it are still sorely lacking in the literature. We discuss the main issues that can influence the final result of a geophysical imaging experiment. In particular, with the view of optimizing the signal-to-noise ratio, we address issues concerning (i) the energy spectrum for muons arriving at different zenith angles, (ii) the muon propagation model through matter and (iii) the characteristics of the muon detector (telescope) that we have designed to perform experiments of muon radiography against the harsh environment usually encountered in the active zone of a volcano. We thus identify factors that can induce either static or dynamic effects and that should be taken into account. We also define a feasibility eq. (32) relating the geometrical characteristics of the telescope and the duration of the experiment to the expected density resolution, in turn a function of the geometrical characteristics of the target structure. This relation is especially important to define the applicability domain of muon radiography and it is utilized to test the suitability of the method to investigate the density distribution inside some candidate target structures.
    Description: Published
    Description: 1348-1361
    Description: 1.3. TTC - Sorveglianza geodetica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Inverse theory; Spatial analysis; Tomography ; 04. Solid Earth::04.02. Exploration geophysics::04.02.07. Instruments and techniques ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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