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  • 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring  (71)
  • Light and electron microscopy  (47)
  • American Geophysical Union  (59)
  • Springer  (58)
  • Krefeld : Geologischer Dienst Nordhein-Westfalen
  • Springer Nature
  • Wiley
  • 2015-2019  (21)
  • 2005-2009  (50)
  • 1970-1974  (47)
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  • 1
    Publication Date: 2021-02-10
    Description: Continuous gravity data collected near the summit eruptive vent at Kīlauea Volcano, Hawaiʻi, during 2011–2015 show a strong correlation with summit-area surface deformation and the level of the lava lake within the vent over periods of days to weeks, suggesting that changes in gravity reflect variations in volcanic activity. Joint analysis of gravity and lava level time series data indicates that over the entire time period studied, the average density of the lava within the upper tens to hundreds of meters of the summit eruptive vent remained low—approximately 1000–1500 kg/m^3. The ratio of gravity change (adjusted for Earth tides and instrumental drift) to lava level change measured over 15 day windows rose gradually over the course of 2011–2015, probably reflecting either (1) a small increase in the density of lava within the eruptive vent or (2) an increase in the volume of lava within the vent due to gradual vent enlargement. Superimposed on the overall time series were transient spikes of mass change associated with inflation and deflation of Kīlauea’s summit and coincident changes in lava level. The unexpectedly strong mass variations during these episodes suggest magma flux to and from the shallow magmatic system without commensurate deformation, perhaps indicating magma accumulation within, and withdrawal from, void space—a process that might not otherwise be apparent from lava level and deformation data alone. Continuous gravity data thus provide unique insights into magmatic processes, arguing for continued application of the method at other frequently active volcanoes.
    Description: Published
    Description: 5477–5492
    Description: 2V. Dinamiche di unrest e scenari pre-eruttivi
    Description: JCR Journal
    Description: restricted
    Keywords: Kīlauea Volcano; gravity changes; lava lake; volcano monitoring ; 04. Solid Earth::04.02. Exploration geophysics::04.02.02. Gravity methods ; 04. Solid Earth::04.03. Geodesy::04.03.05. Gravity variations ; 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: 2021-03-01
    Description: A new period of eruptive activity started at Turrialba volcano, Costa Rica, in 2010 after almost 150 years of quiescence. This activity has been characterized by sporadic explosions whose frequency clearly increased since October 2014. This study aimed to identify the mechanisms that triggered the resumption of this eruptive activity and characterize the evolution of the phenomena over the past 2 years. We integrate 3He/4He data available on fumarole gases collected in the summit area of Turrialba between 1999 and 2011 with new measurements made on samples collected between September 2014 and February 2016. The results of a petrological investigation of the products that erupted between October 2014 and May 2015 are also presented. We infer that the resumption of eruptive activity in 2010 was triggered by a replenishment of the plumbing system of Turrialba by a new batch of magma. This is supported by the increase in 3He/4He values observed since 2005 at the crater fumaroles and by comparable high values in September 2014, just before the onset of the new eruptive phase. The presence of a number of fresh and juvenile glassy shards in the erupted products increased between October 2014 and May 2015, suggesting the involvement of new magma with a composition similar to that erupted in 1864–1866. We conclude that the increase in 3He/4He at the summit fumaroles since October 2015 represents strong evidence of a new phase of magma replenishment, which implies that the level of activity remains high at the volcano.
    Description: Published
    Description: 3V. Proprietà dei magmi e dei prodotti vulcanici
    Description: 4V. Dinamica dei processi pre-eruttivi
    Description: 5V. Dinamica dei processi eruttivi e post-eruttivi
    Description: JCR Journal
    Keywords: Turrialba volcano ; eruptive activity ; 3He/4He ; fumarole gases ; glassy shards ; juvenile component ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.07. Tectonophysics::04.07.08. Volcanic arcs ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 3
    Publication Date: 2021-04-07
    Description: Integrating geodetic, seismic, and petrological data for a recent eruptive episode at Mount Etna has enabled us to define the history of magma storage and transfer within the multilevel structure of the volcano, providing spatial and temporal constraints for magma movements before the eruption. Geodetic data related to the July–August 2014 activity provide evidence of a magma reservoir at ~4 km below sea level. This reservoir pressurized from late March 2014 and fed magmas that were then erupted from vents on the lower eastern flank of North-East Crater (NEC) and at New South-East Crater (NSEC) summit crater during the July eruptive activity. Magma drainage caused its depressurization since mid-July. Textural and microanalytical data obtained from plagioclase crystals indicate similar disequilibrium textures and compositions at the cores in lavas erupted at the base of NEC and NSEC, suggesting comparable deep histories of evolution and ascent. Conversely, the compositional differences observed at the crystal rims have been associated to distinct degassing styles during storage in a shallow magma reservoir. Seismic data have constrained depth for a shallow part of the plumbing system at 1–2 km above sea level. Timescales of magma storage and transfer have also been calculated through diffusion modeling of zoning in olivine crystals of the two systems. Our data reveal a common deep history of magmas from the two systems, which is consistent with a recharging phase by more mafic magma between late March and early June 2014. Later, the magma continued its crystallization under distinct chemical and physical conditions at shallower levels.
    Description: The petrological part of this study was supported by the FIR 2014 research grant to Marco Viccaro from the University of Catania (Italy), grant number 2F119B, title of the project “Dynamics of evolution, ascent and emplacement of basic magmas: case-studies from eruptive manifestations of Eastern Sicily”.
    Description: Published
    Description: 5659–5678
    Description: 2V. Dinamiche di unrest e scenari pre-eruttivi
    Description: 3V. Dinamiche e scenari eruttivi
    Description: JCR Journal
    Description: restricted
    Keywords: Petrology ; eruption ; GPS ; volcano seismology ; Etna ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations ; 04. Solid Earth::04.03. Geodesy::04.03.07. Satellite geodesy ; 04. Solid Earth::04.04. Geology::04.04.07. Rock geochemistry ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 4
    Publication Date: 2017-04-04
    Description: To evaluate the volcanic processes leading to the 25–26 October 2013 lava fountain at Mount Etna, we jointly investigated gravity, GPS, and DInSARmeasurements covering the late-June to early-November time interval. We used finite element modeling to infer a shallow magmatic reservoir which (i) inflated since July 2013, (ii) fed the volcanic activity at the summit craters during 25–26 October, and (iii) deflated due to magma drainage related to this volcanic activity. We suggested that this reservoir belongs to a shallow volume, which is located beneath the summit area and is replenished by magma rising from deep reservoirs and fed the short-term volcanic activity, representing a persistent shallow magmatic plumbing system of Etna. In addition, the model results show that there is a large discrepancy between the erupted and shallow reservoir deflation volumes, which could be reasonably attributable to a highly compressible volatile-rich magma.
    Description: Published
    Description: 3246–3253
    Description: 2V. Dinamiche di unrest e scenari pre-eruttivi
    Description: JCR Journal
    Description: open
    Keywords: Gravity and deformation signatures of the 26 October 2013 Mount Etna lava fountain ; Integrated finite element-based inversion of gravity and GPS data ; Inference on a highly compressible volatile-rich magma in the magmatic reservoir ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 5
    Publication Date: 2017-04-04
    Description: Piton de la Fournaise (PdF) is recognised as one of the world’s most active volcanoes in terms of eruptive frequency and the substantial quantity of lava produced. Yet, with the sole exception of rather modest intracrateric fumarole activity, this seems to be in contrast with an apparent absence of any type of natural fluid emission during periods of quiescence. Measurement campaigns were undertaken during a long-lasting quiescent period (2012-2014) and just after a short lived summit eruption (June 2014) in order to identify potential degassing areas in relation to the main structural features of the volcano (ex. rift zones) with the aim of developing a broader understanding of the geometry of the plumbing and degassing system. In order to assess the possible existence of anomalous soil CO2 flux, 513 measurements were taken along transects roughly orthogonal to the known tectonic lineaments crossing PdF edifice. In addition, 53 samples of gas for C isotope analysis were taken at measurement points that showed a relatively high CO2 concentration in the soil. CO2 flux values range from 10 to 1300 g m-2 d-1 while 13C are between -26.6 to -8‰. The results of our investigation clearly indicate that there is a strong spatial correlation between the anomalous high values of diffusive soil emissions and the main rift zones cutting the PdF massif and, moreover, that generally high soil CO2 fluxes show a d13C signature clearly related to a magmatic origin.
    Description: INSU (CNRS) and La Réunion Préfecture (Projet pour la quantification de l’aléa volcanique à La Réunion)
    Description: Published
    Description: 4388–4404
    Description: 2V. Dinamiche di unrest e scenari pre-eruttivi
    Description: JCR Journal
    Description: restricted
    Keywords: CO2 soil degassing anomalies at Piton de la Fournaise ; d13C magmatic signature ; Close link between anomalous CO2 degassing and the main seismotectonic structures ; 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::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 6
    Publication Date: 2017-04-04
    Description: This paper focuses on the chemical composition changes in soil gases through both a theoretical model and laboratory experiments. The model describes the one-dimensional mass transfer process, which is triggered by changes in the flux parameters of the system, and the time-dependent evolution of the composition of the soil gases as a function of i) the pristine gas mixture, ii) the diffusivity of the chemicals, and iii) the thickness of the transited medium. Carbon dioxide (CO2), hydrogen (H2), and helium (He) were used in a laboratory-scale flux simulator to investigate the evolution of the gas composition profile in an artificial soil of constant thickness. The agreement between the theoretical calculations and the experimental results supports the validity of the model. Our results indicate a good reproducibility of the transient changes in the concentrations of CO2, He, and H2 in CO2-rich gas mixtures that contain He and H2 as trace gases. Finally, the theoretical results were used to analyze the H2 and CO2 continuous monitoring data collected at Etna volcano in 2010
    Description: Published
    Description: 1565–1583
    Description: 2V. Dinamiche di unrest e scenari pre-eruttivi
    Description: 5V. Sorveglianza vulcanica ed emergenze
    Description: 1IT. Reti di monitoraggio e Osservazioni
    Description: JCR Journal
    Description: open
    Keywords: Soil gases ; Volcanic gas composition ; Hydrogen ; Carbon dioxide ; CO2 ; Helium ; 03. Hydrosphere::03.04. Chemical and biological::03.04.05. Gases ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 7
    Publication Date: 2017-04-04
    Description: On 28 December 2014, eruptive activity resumed at Mount Etna with fire fountain activity feeding two lava flows on the eastern and southwestern upper flanks of the volcano. Unlike all previous summit activity, this eruption produced clear deformation at the summit of the volcano. GPS displacements and Sentinel-1A ascending interferogramswere calculated in order to image the ground deformation pattern accompanying the eruption. The displacements observed by GPS depict a local ground deformation pattern, affecting only the upperpart of the volcano.Despite snowcover onthe summit, differential interferometry synthetic aperture radar (DInSAR) data allowed obtainingmore detail onthe grounddeformation pattern on the upper eastern side of the volcano. Three-dimensional GPS displacements inversion located a very shallow NE-SW intrusion just beneath the New Southeast Crater. However, this model cannot justify all the deformation observed by DInSAR thus revealing a gravitational failure of the lava flow field
    Description: Published
    Description: 2727–2733
    Description: 3V. Dinamiche e scenari eruttivi
    Description: JCR Journal
    Description: restricted
    Keywords: Sentinel-1A interferogram details the ground deformation field ; GPS data are analyzed for modeling the dyke intrusion ; Data comparison highlights an incipient slope failure ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 8
    Publication Date: 2020-12-14
    Description: Explosive volcanic eruptions are defined as the violent ejection of gas and hot fragments from a vent in the Earth's crust. Knowledge of ejection velocity is crucial for understanding and modeling relevant physical processes of an eruption, and yet direct measurements are still a difficult task with largely variable results. Here we apply pioneering high-speed imaging to measure the ejection velocity of pyroclasts from Strombolian explosive eruptions with an unparalleled temporal resolution. Measured supersonic velocities, up to 405 m/s, are twice higher than previously reported for such eruptions. Individual Strombolian explosions include multiple, sub-second-lasting ejection pulses characterized by an exponential decay of velocity. When fitted with an empirical model from shock-tube experiments literature, this decay allows constraining the length of the pressurized gas pockets responsible for the ejection pulses. These results directly impact eruption modeling and related hazard assessment, as well as the interpretation of geophysical signals from monitoring networks.
    Description: INGV-DPC “V2” and “Paroxysm”, FIRB-MIUR “Research and Development of New Technologies for Protection and Defense of Territory from Natural Risks”, and FP7-PEOPLE-IEF-2008 – 235328 Projects
    Description: Published
    Description: L02301
    Description: 3V. Dinamiche e scenari eruttivi
    Description: JCR Journal
    Description: open
    Keywords: strombolian ; ejection velocity ; explosive eruption ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 9
    Publication Date: 2020-12-15
    Description: We have analyzed a focal mechanism data set for Mount Vesuvius, consisting of 197 focal mechanisms of events recorded from 1999 to 2012. Using different approaches and a comparison between observations and numerical models, we have determined the spatial variations in the stress field beneath the volcano. The main results highlight the presence of two seismogenic volumes characterized by markedly different stress patterns. The two volumes are separated by a layer where the seismic strain release shows a significant decrease. Previous studies postulated the existence, at about the same depth, of a ductile layer allowing the spreading of the Mount Vesuvius edifice. We interpreted the difference in the stress pattern within the two volumes as the effect of a mechanical decoupling caused by the aforementioned ductile layer. The stress pattern in the top volume is dominated by a reverse faulting style, which agrees with the hypothesis of a seismicity driven by the spreading process. This agrees also with the persistent character of the seismicity located within this volume. Conversely, the stress field determined for the deep volume is consistent with a background regional field locally perturbed by the effects of the topography and of heterogeneities in the volcanic structure. Since the seismicity of the deep volume shows an intermittent behavior and has shown to be linked to geochemical variations in the fumaroles of the volcano, we hypothesize that it results from the effect of fluid injection episodes, possibly of magmatic origin, perturbing the pore pressure within the hydrothermal system.
    Description: Published
    Description: 1181–1199
    Description: 4T. Fisica dei terremoti e scenari cosismici
    Description: 2V. Dinamiche di unrest e scenari pre-eruttivi
    Description: 5V. Sorveglianza vulcanica ed emergenze
    Description: JCR Journal
    Description: restricted
    Keywords: vesuvius ; stress inversion ; focal mechanisms ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques ; 04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 10
    Publication Date: 2017-04-04
    Description: A new eruption started at Stromboli on August 6, 2014, which had been preceded by 2 months of increased Strombolian activity and several lava overflows from the craters. The eruption was characterized by a lava effusion in Sciara del Fuoco from a fracture at 650 m a.s.l. that lasted until November 13–17. Here we present the first geochemical observations of this eruption, based on the soil CO2 flux in the summit area, and on 3He/4He ratios in the thermal waters near Stromboli village. We infer that this eruption was triggered by the gradual replenishment of the feeding system by a CO2- and 3He-rich magma at the end of 2013 and after June 2014, suggested by the increase in 3He/4He ratio before eruption, which reached its highest value since 2007. We thus infer that this eruption was unusual and we finally speculate on the evolutionary scenario of post eruption.
    Description: Published
    Description: 2235–2243
    Description: 2V. Dinamiche di unrest e scenari pre-eruttivi
    Description: 3V. Dinamiche e scenari eruttivi
    Description: 5V. Sorveglianza vulcanica ed emergenze
    Description: JCR Journal
    Description: restricted
    Keywords: Stromboli ; eruption ; soil CO2 flux ; 3He/4He ratio ; thermal waters ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 11
    Publication Date: 2020-02-24
    Description: This work arises from the field observations made during the civil protection emergency period connected to the 2007 Stromboli eruption. We observed changes in the shallow feeding system of the volcano to which we give a volcanological interpretation and the relative implications. Here we describe the processes that occurred in the upper feeding system from the end of the 2007 effusive eruption on 3 April to the renewal of the strombolian explosive activity at the summit craters (30 June), interpreted using multidisciplinary data. We used thermal camera data collected both from helicopter and from a fixed station at 400 m to retrieve the evolving summit crater activity. These data, compared with seismic signals and published geochemical records, allowed us to detail the shifting of the degassing activity within the crater terrace from NE to SW, occurred between 15 and 25 April 2007 prior to the resumption of the strombolian activity. In particular, from mid-April, a gradual SW displacement in the maximum apparent temperatures was recorded at the vents within the summit craters, together with a change in the very long period location and confirmed by variations in geochemical indicators (CO2∕SO2 plume ratios and CO2 fluxes) from literature. The shallow feeding system experienced a major readjustment after the end of the effusive activity, determining variations in the pressure leakage of the source, slowly deepening and shifting toward SW. All these data, together with the framework supplied by previous structural surveys, allowed us to propose that the compaction of debris accumulated in the uppermost conduit by inward crater collapses, occurred in early March, produced the observed anomalies. At Stromboli, major morphology changes, taking place in the following years, were anticipated by these small and apparently minor processes occurred in the upper feeding system. Other studies are relating similar changes to modifications of the eruptive activity also at other open-conduit volcanoes, so we believe that it may be important to have a constant monitoring of these phenomena in order to better understand their shallow feeding systems.
    Description: This paper was partially supported by a grant to S.C. (Project INGV-DPC Paroxysm V2/03, 2008–2010) funded by the Istituto Nazionale di Geofisica e Vulcanologia and by the Italian Civil Protection.
    Description: Published
    Description: 7376–7395
    Description: 2V. Dinamiche di unrest e scenari pre-eruttivi
    Description: JCR Journal
    Description: restricted
    Keywords: Stromboli volcano ; thermal imaging ; multidisciplinary study ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 12
    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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  • 13
    Publication Date: 2017-04-04
    Description: An array of nine three-component broadband seismometers was deployed in two different configurations on Stromboli volcano. The analysis of the seismic wavefield related to volcanic explosions revealed some observations which offer a completely new insight into the internal dynamics of a volcano. These new observations are restricted to the low-frequency range below 1 Hz and underline, therefore, the superiority of broadband recordings over conventional short-period observations. Surprisingly simple wavelets indicate an initially contracting source mechanism. Gas-jets that could not be seen in a short-period seismic record at all, generate a clear dilatational wavelet in a broadband recording suggesting the same contracting source mechanism. The analysis of particle motion and seismic array techniques permits a location of the seismic source. We find low-frequency signals of 3s and 6s period that are not related to eruptions and do not share a common source with the eruption-related events. A video recording of visible volcanic activity at the crater region allows one to correlate precisely eruptive features with seismic signals.
    Description: Published
    Description: 749-752
    Description: 5V. Sorveglianza vulcanica ed emergenze
    Description: N/A or not JCR
    Description: restricted
    Keywords: Stromboli ; volcano seismology ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 14
    Publication Date: 2017-04-04
    Description: High-speed imaging of explosive eruptions at Stromboli (Italy), Fuego (Guatemala), and Yasur (Vanuatu) volcanoes allowed visualization of pressure waves from seconds-long explosions. From the explosion jets, waves radiate with variable geometry, timing, and apparent direction and velocity. Both the explosion jets and their wave fields are replicated well by numerical simulations of supersonic jets impulsively released from a pressurized vessel. The scaled acoustic signal from one explosion at Stromboli displays a frequency pattern with an excellent match to those from the simulated jets. We conclude that both the observed waves and the audible sound from the explosions are jet noise, i.e., the typical acoustic field radiating from high-velocity jets. Volcanic jet noise was previously quantified only in the infrasonic emissions from large, sub-Plinian to Plinian eruptions. Our combined approach allows us to define the spatial and temporal evolution of audible jet noise from supersonic jets in small-scale volcanic eruptions.
    Description: INGV-DPC “V2” and “Paroxysm,” FIRB-MIUR “Research and Development of New Technologies for Protection and Defense of Territory from Natural Risks,” and FP7-PEOPLE-IEF-2008–235328 “NEMOH” ITN projects
    Description: Published
    Description: 3096–3102
    Description: 3V. Dinamiche e scenari eruttivi
    Description: JCR Journal
    Description: restricted
    Keywords: jet noise ; volcano acoustics ; Stromboli ; Yasur ; Fuego ; strombolian eruption ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 15
    Publication Date: 2017-04-04
    Description: The fumarolic gas output has not been quantified for any of the currently deforming calderas worldwide, due to the lack of suitable gas flux sensing techniques. In view of resumption of ground uplift (since 2005) and the associated variations in gas chemistry, Campi Flegrei, in southern Italy, is one of the restless calderas where gas flux observations are especially necessary. Here we report the first ever obtained estimate of the Campi Flegrei fumarolic gas output, based on a set of MultiGAS surveys (performed in 2012 and 2013) with an ad-hoc-designed measurement setup. We estimate that the current Campi Flegrei fumarolic sulphur (S) flux is low, on the order of 1.5–2.2 tons/day, suggesting substantial scrubbing of magmatic S by the hydrothermal system. However, the fumarolic carbon dioxide (CO2) output is ∼460±160 tons/day (mean±SD), which is surprisingly high for a dormant volcano in the hydrothermal stage of activity, and results in a combined (fumaroles + soil) CO2 output of ∼1560 tons/day. Assuming magma to be the predominant source, we propose that the current CO2 output can be supplied by either (i) a large (0.6–4.6 km3), deeply stored (〉7 km) magmatic source with low CO2 contents (0.05–0.1 wt%) or (ii) by a small to medium-sized (∼0.01–0.1 km3) but CO2-rich (2 wt%) magma, possibly stored at pressures of ∼100 to 120 MPa. Independent geophysical evidence (e.g., inferred from geodetic and gravity data) is needed to distinguish between these two possibilities.
    Description: Published
    Description: 4153–4169
    Description: 2V. Dinamiche di unrest e scenari pre-eruttivi
    Description: JCR Journal
    Description: restricted
    Keywords: Campi Flegrei ; calderas ; gas output ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 16
    Publication Date: 2017-04-04
    Description: The interpretation of dynamic processes that occur in volcanic calderas is not simple. The ground deformations and the local seismicity, which in other volcanic contexts are usually regarded as precursors to eruption, in caldera environment in many cases are not followed by any eruption. We formulate a general hypothesis that can explain these behaviors. Our hypothesis is that the intrusion of a sill can be responsible for the dynamics observed during unrest at calderas. In order to investigate the reliability of this hypothesis, we developed a dynamic model of sill intrusion in a shallow volcanic environment. In our model, the sill, fed by a deeper magma reservoir, intrudes below a horizontal elastic plate, representing the overlying rocks, and expands with axisymmetric geometry. The model is based on the numerical solution of the equation for the elastic plate, coupled with a Navier-Stokes equation for simulating the dynamics of the sill intrusion. We performed a number of simulations, with the objective of showing the main features of the model. In the experiments, when the feeding process stops, the vertical movement reverses its trend and the area of maximum uplift undergoes subsidence. Under certain conditions the subsidence can occur even during the intrusion of the sill. The stress field produced by the intrusion is mainly concentrated in a circular zone that follows the sill intrusion front. The features predicted by the model are consistent with many observations carried out on different calderas as reported in the scientific literature.
    Description: Published
    Description: 3986–4000
    Description: 2V. Dinamiche di unrest e scenari pre-eruttivi
    Description: 3V. Dinamiche e scenari eruttivi
    Description: 5V. Sorveglianza vulcanica ed emergenze
    Description: JCR Journal
    Description: restricted
    Keywords: sill intrusion ; caldera ; volcano geodesy ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.05. Mathematical geophysics::05.05.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 17
    Publication Date: 2017-04-04
    Description: Mt Etna volcano (Italy) typically generates lava fountains and Strombolian eruptions from the summit craters, producing significant emissions of tephra which may cause moderate to high impact both in the atmosphere and on the ground. However, we have also witnessed a number of minor ash emissions that, although far less powerful, may pose considerable volcanic hazards. In this paper, we deal with three ash emissions occurring in 2010 (8 April at Southeast Crater, 25 August at Bocca Nuova, and 14–15 November at Northeast Crater), correlating their volcanological features with the associated seismoacoustic signals. We provide details regarding the chronology, eruption column, dispersal of the deposit, and texture (grain size, componentry and morphology) of the emitted ash. Each eruptive episode has also been characterized by means of seismo-acoustic analyses evaluating the volcanic acoustic-seismic ratio (VASR). Furthermore, the source of volcanic tremor recorded from March to December 2010 was localized. The joint volcanological and seismo-acoustic analyses allowed distinguishing two main kinds of ash emissions: types a (8 April and 25 August) and b (14–15 November). Regarding the former, the accumulation of gas below a dense cap rock obstructing the conduit vent, giving rise, with the uncorking, to impulsive explosivity, was hypothesized. The latter type instead is characterized by a longer-lasting and less explosivity, likely due to the existence of open conduit conditions. Therefore, type b ash emissions are less hazardous than type a. This simple model, regarding minor explosive activity, may constitute a starting point to assess the volcanic risk from unexpected explosions.
    Description: Published
    Description: 51-70
    Description: 3V. Dinamiche e scenari eruttivi
    Description: JCR Journal
    Description: reserved
    Keywords: Mt Etna ; seismo-acoustic signals ; ash emissions ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 18
    Publication Date: 2017-04-04
    Description: Between January 2011 and April 2013, Mt. Etna's eruptive activity consisted of episodic intra-crater strombolian explosions and paroxysms from Bocca Nuova, Voragine, and the New South-East (NSEC) summit craters, respectively. Eruptions from NSEC consisted of initial increasing strombolian activity and lava flow output, passing to short-lasting lava fountaining. In this study we present seismic, infrasound, radiometric, plume SO2 and HCl fluxes and geodetic data collected by the INGV monitoring system between May 2012 and April 2013. The multi-parametric approach enabled characterization of NSEC eruptive activity at both daily and monthly time scales and tracking of magma movement within Mt. Etna's plumbing system. While seismic, infrasound and radiometric signals give insight on the energy and features of the 13 paroxysms fed by NSEC, SO2 and halogen fluxes shed light on the likely mechanisms triggering the eruptive phenomena. GPS data provided clear evidence of pressurization of Mt. Etna's plumbing system from May 2012 to middle February 2013 and depressurization during the February-April 2013 eruptive activity. Taking into account geochemical data, we propose that the paroxysms' sequence represented the climax of a waxing-waning phase of degassing that had started as early as December 2012, and eventually ended in April 2013. Integration of the multidisciplinary observations suggests that the February-April 2013 eruptive activity reflects a phase of release of a volatile-rich batch of magma that had been stored in the shallow volcano plumbing system at least four months before, and with the majority of gas released between February and March 2013. This article is protected by copyright. All rights reserved.
    Description: European FP7 MED-SUV (MEditerranean SUpersite Volcanoes). Grant Number: 308665 European Research Council European FP7 (FP/2007-2013)/ERC. Grant Number: 279802 SIGMA (Sistema Integrato di sensori in ambiente cloud per la Gestione Multirischio Avanzata)
    Description: Published
    Description: 1932–1949
    Description: 3V. Dinamiche e scenari eruttivi
    Description: JCR Journal
    Description: restricted
    Keywords: Mt. Etna ; paroxysmal activity ; SO2 and HCl fluxes ; infrasound and seismic signals ; radiometry ; ground deformation ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 19
    Publication Date: 2017-04-04
    Description: We present the results of laboratory experiments on the aggregation and disaggregation of colliding volcanic ash particles. Ash particles of different composition and size 〈90 µm were held in turbulent suspension and filmed in high speed while colliding, aggregating, and disaggregating, forming a growing layer of electrostatically bound particles along a vertical plate. At room conditions and regardless of composition, 60–80% of the colliding particles smaller than 32 µm remained aggregated. In contrast, aggregation of particles larger than 63 µm was negligible, and, when a layer formed, periods when disaggregation (mainly by collisions or drag) exceeded aggregation occurred twice as frequently than for smaller particles. An empirical relationship linking the aggregation index, i.e., the effective fraction of aggregated particles surviving disaggregation, to the mean particle collision kinetic energy is provided. Our results have potential implications on the dynamics of volcanic plumes and ash mobility in the environment.
    Description: INGV-DPC project V1 “Probabilistic evaluation of volcanic hazard”; EU Seventh Programme FP7 “MED-SUV” grant agreement 308665
    Description: Published
    Description: 1068–1075
    Description: 3V. Dinamiche e scenari eruttivi
    Description: 2IT. Laboratori sperimentali e analitici
    Description: JCR Journal
    Description: restricted
    Keywords: volcanic ash ; disaggregation ; experimental modeling ; volcanic plumes ; aggregation processes ; colliding particles ; sticking rate ; 01. Atmosphere::01.01. Atmosphere::01.01.07. Volcanic effects ; 04. Solid Earth::04.08. Volcanology::04.08.02. Experimental volcanism ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 20
    Publication Date: 2021-12-15
    Description: Relationships between frequency and intensity of volcanic eruptions are actively sought by geophysicists for both monitoring and research purposes. By analyzing surveillance videos of persistent volcanic activity at Stromboli (Italy), we derived the frequency and jet height of 〉4000 explosions that occurred in 72 h-long time windows sampled yearly from 2005 to 2009. We found a positive relationship linking explosion frequency and jet height (linked to eruption intensity) when averaging the two parameters over time intervals from hours to days, with a stronger correlation for longer intervals. We interpret this behavior as the response of the magmatic system to variable influx of magma and gas at depth, increased flux at depth causing more frequent and stronger explosions at the surface. This relationship entails concurrent control of source processes over explosion frequency and intensity, directly impacting modeling of explosion sources at persistently active volcanoes in general and hazard assessment at Stromboli in particular.
    Description: DPC-INGV Project V2 “Paroxysm”
    Description: Published
    Description: 1–5
    Description: 3V. Dinamiche e scenari eruttivi
    Description: JCR Journal
    Description: reserved
    Keywords: Stromboli ; Strombolian frequency ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 21
    Publication Date: 2023-01-19
    Description: In situ measurements have been the basis for monitoring volcanic gas emissions for many years and—being complemented by remote sensing techniques—still play an important role to date. Concerning in situ techniques for sampling a dilute plume, an increase in accuracy and a reduction of detection limits are still necessary for most gases (e.g., CO2, SO2, HCl, HF, HBr, HI). In this work, the Raschig-Tube technique (RT) is modified and utilized for application on volcanic plumes. The theoretical and experimental absorption properties of the RT and the Drechsel bottle (DB) setups are characterized and both are applied simultaneously to the well-established Filter packs technique (FP) in the field (on Stromboli Island and Mount Etna). The comparison points out that FPs are the most practical to apply but the results are errorprone compared to RT and DB, whereas the RT results in up to 13 times higher analyte concentrations than the DB in the same sampling time. An optimization of the analytical procedure, including sample pretreatment and analysis by titration, Ion Chromatography, and Inductively Coupled Plasma Mass Spectrometry, led to a comprehensive data set covering a wide range of compounds. In particular, less abundant species were quantified more accurately and iodine was detected for the first time in Stromboli’s plume. Simultaneously applying Multiaxis Differential Optical Absorption Spectroscopy (MAX-DOAS) the chemical transformation of emitted bromide into bromine monoxide (BrO) from Stromboli and Etna was determined to 3–6% and 7%, respectively, within less than 5 min after the gas release from the active vents.
    Description: Published
    Description: 2797–2820
    Description: 5V. Sorveglianza vulcanica ed emergenze
    Description: JCR Journal
    Description: restricted
    Keywords: plume ; volcano ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 22
    Publication Date: 2017-04-04
    Description: Volcanoes deform as a consequence of the rise and storage of magma; once magma reaches a critical pressure, an eruption occurs. However, how the edifice deformation relates to its eruptive behavior is poorly known. Here, we produce a joint interpretation of spaceborne InSAR deformation measurements and volcanic activity at Mt. Etna (Italy), between 1992 and 2006. We distinguish two volcano-tectonic behaviors. Between 1993 and 2000, Etna inflated with a starting deformation rate of 1 cm yr 1 that progressively reduced with time, nearly vanishing between 1998 and 2000; moreover, low-eruptive rate summit eruptions occurred, punctuated by lava fountains. Between 2001 and 2005, Etna deflated, feeding higher-eruptive rate flank eruptions, along with large displacements of the entire East-flank. These two behaviors, we suggest, result from the higher rate of magma stored between 1993 and June 2001, which triggered the emplacement of the dike responsible for the 2001 and 2002–2003 eruptions. Our results clearly show that the joint interpretation of volcano deformation and stored magma rates may be crucial in identifying impending volcanic eruptions.
    Description: This work was partly funded by INGV and the Italian DPC and was supported by ASI, the Preview Project and CRdC-AMRA. DPC-INGV Flank project providing the funds for the publication fees.
    Description: Published
    Description: L02309
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 1.10. TTC - Telerilevamento
    Description: 3.6. Fisica del vulcanismo
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: 4.5. Degassamento naturale
    Description: JCR Journal
    Description: partially_open
    Keywords: deformation ; eruptions ; Mt. Etna ; eruptive cycle ; InSAR ; 04. Solid Earth::04.01. Earth Interior::04.01.99. General or miscellaneous ; 04. Solid Earth::04.01. Earth Interior::04.01.02. Geological and geophysical evidences of deep processes ; 04. Solid Earth::04.03. Geodesy::04.03.99. General or miscellaneous ; 04. Solid Earth::04.03. Geodesy::04.03.06. Measurements and monitoring ; 04. Solid Earth::04.03. Geodesy::04.03.07. Satellite geodesy ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.07. Tectonophysics::04.07.99. General or miscellaneous ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 23
    Publication Date: 2017-04-04
    Description: Accepted for publication in Journal of Geophysical Research. Copyright (2009) American Geophysical Union. Further reproduction or electronic distribution is not permitted.
    Description: Using thermal infrared images recorded by a permanent thermal camera network maintained on Stromboli volcano (Italy), together with satellite and helicopter-based thermal image surveys, we have compiled a chronology of the events and processes occurring before and during Stromboli’s 2007 effusive eruption. These digital data also allow us to calculate the effusion rates and lava volumes erupted during the effusive episode. At the onset of the 2007 eruption, two parallel eruptive fissures developed within the North East crater, eventually breaching the NE flank of the summit cone and extending along the eastern margin of the Sciara del Fuoco. These fed a main effusive vent at 400 m a.s.l. to feed lava flows that extended to the sea. The effusive eruption was punctuated, on 15 March, by a paroxysm with features similar to the 5 April paroxysm that occurred during the 2002-03 effusive eruption. A total of between 3.2 x 106 m3 and 11 x 106 m3 of lava was erupted during the 2007 eruption over 34 days of effusive activity. More than half of this volume was emplaced during the first 5.5 days of the eruption. Although the 2007 effusive eruption had a comparable erupted volume to the previous (2002-03) effusive eruption, it had a shorter duration and thus a mean output rate (= total volume divided by eruption duration) that was one order of magnitude greater than the 2002-03 event (~2.4 m3 s-1 compared with 0.32±0.28 m3 s-1). In this paper, we discuss similarities and differences between these two effusive events, and interpret the processes occurring in 2007 in terms of the recent dynamics witnessed at Stromboli.
    Description: This paper was partially supported by a grant to S. Calvari (Project INGV-DPC Paroxysm V2/03, 2008-2010) funded by the Istituto Nazionale di Geofisica e Vulcanologia and by the Italian Civil Protection. Satellite-based effusion rate work by A. Steffke and A. Harris was supported by NASA grant NNG04GO64G "New Tools for Advanced Hot Spot Tracking".
    Description: In press
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: JCR Journal
    Description: open
    Keywords: Thermal mapping ; Stromboli ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 24
    Publication Date: 2017-04-04
    Description: Large variations of the CO2 flux through the soil were observed between November 2002 and January 2006 at Mt. Etna volcano. In many cases, the CO2 flux was strongly influenced by changes in air temperature and atmospheric pressure. A new filtering method was then developed to remove the atmospheric influences on soil CO2 flux and, at the same time, to highlight the variations strictly related to volcanic activity. Successively, the CO2 corrected data were quantitatively compared with the spectral amplitude of the volcanic tremor by cross correlation function, cross-wavelet spectrum and wavelet coherence. These analyses suggested that the soil CO2 flux variations preceded those of volcanic tremor by about 50 days. Given that volcanic tremor is linked to the shallow (a few kilometer) magma dynamics and soil CO2 flux related to the deeper (*12 km b.s.l.) magma dynamics, the “delayed similarity” between the CO2 flux and the volcanic tremor amplitude was used to assess the average speed in the magma uprising into the crust, as about 170–260 m per day. Finally, the large amount of CO2 released before the onset of the 2004–2005 eruption indicated a deep ingression of new magma, which might have triggered such an eruption.
    Description: In press
    Description: N/A or not JCR
    Description: reserved
    Keywords: Mt. Etna ; Soil CO2 flux ; Volcanic tremor ; Cross-wavelet spectrum ; Wavelet coherence ; Cross correlation function ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data ; 05. General::05.02. Data dissemination::05.02.02. Seismological data
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 25
    Publication Date: 2021-01-27
    Description: We report the first combined measurements of the composition and flux of gas emitted from Nyiragongo volcano by ground-based remote-sensing techniques. Ultraviolet spectroscopic measurements made in May/June 2005 and January 2006 indicate average SO2 emission rates of 38 kg s−1 and 23 kg s−1, respectively. Open-path Fourier transform infrared spectroscopic measurements obtained in May/June 2005, January 2006, and June 2007 indicate average molar proportions of 70, 24, 4.6, 0.87, 0.26, 0.11, and 0.0016% for H2O, CO2, SO2, CO, HCl, HF, and OCS, respectively. The composition of the plume was remarkably similar in 2005, 2006, and 2007, with little temporal variation in proportions of CO2, SO2, and CO, in particular, on the scale of seconds or days or even between the three field campaigns that span a period of 24 months. This stability persisted despite a wide range of degassing behaviors on the surface of the summit crater's lava lake (including discrete strombolian bursts and lava fountains) and variations in the SO2 emission rate. We explain these observations by a regime of steady state degassing in which bubbles nucleate and ascend in chemical equilibrium with the convecting magma. Short-term (seconds to minutes) temporal fluctuations in the SO2–HCl–HF composition were observed, and these are attributed to shallow degassing processes.
    Description: Published
    Description: Q02017
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Nyiragongo ; volcanic gas emissions ; FTIR ; DOAS ; remote sensing ; spectroscopy ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 26
    Publication Date: 2021-07-14
    Description: From 25 November to 2 December 2006, the first active seismic tomography experiment at Stromboli volcano was carried out with the cooperation of four Italian research institutions. Researchers on board the R/V Urania of the Italian National Council of Research (CNR), which was equipped with a battery of four 210- cubic- inch generated injection air guns (GI guns), fired more than 1500 offshore shots along profiles and rings around the volcano.
    Description: DPC/INGV agreement 2004-2006
    Description: Published
    Description: 269-270
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.6. Fisica del vulcanismo
    Description: N/A or not JCR
    Description: reserved
    Keywords: Stromboli ; seismic tomography ; air-gun ; 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::04.06.10. Instruments and techniques ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 27
    Publication Date: 2017-04-04
    Description: The soil CO2 flux on Mt. Etna as recorded by the ETNAGAS network (an automatic system for measuring soil CO2 flux and meteorological parameters) started to increase strongly about 5 months prior to the onset of the 2004–2005 eruption and decreased a few months before the end of the eruption. Time delays in the occurrences of anomalies in soil CO2 flux at different sites in the geochemical network constrain the relationship between soil CO2 flux distributions and the tectonic framework of Etna volcano. The anomalies observed before the 2004–2005 eruption support the intrusion of new undegassed magma into the upper feeding system of the volcano (〈20 km below sea level). Magma subsequently rose slowly in the volcano conduits, thereby triggering the onset of the 2004–2005 eruption. The time delays in the occurrences of anomalies in combination with spectral analysis indicate the importance of tectonic and volcanotectonic structures in driving the ascent of deep gases within the crust. Moreover, greatest amplitude pulsations of the low-frequency components of the CO2 flux signals were correlated with the paroxystic activities of the 2004–2005 eruption. This study confirms that CO2 flux variation is a useful indicator for volcanic activity in the surveillance of the Mt. Etna and similar basaltic volcanoes.
    Description: Dipartimento Protezione Civile Ministero degli Interni
    Description: Published
    Description: B09206
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: JCR Journal
    Description: reserved
    Keywords: CO2 flux ; Continuous monitoring of soil CO2 flux ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 28
    Publication Date: 2017-04-04
    Description: The 2002–2003 effusive eruption of Stromboli volcano represents an excellent opportunity to investigate the transition from effusive to explosive activity at an open-conduit basaltic system, when activity migrated from effusive vents, at the base of the craters, to summit explosions. The transition is investigated here through the analysis of very long period seismicity, delay times between infrasonic and thermal onsets of explosions, and SO2 flux recorded during a 1-year period. The synergy of the multiple geophysical observations points to a magma-driven migration of the magma column. Here the increased magma supply at the eruption onset lead to opening of effusive fissures, which draining the magma in the shallow conduit caused the decrease of the magma level. The decrease of the magma supply at the end of the effusion lead to sealing of effusive fissures, upraise of the magma level within the conduit, and reestablishment of explosive activity from the summit vents.
    Description: Unpublished
    Description: 11
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: 1.10. TTC - Telerilevamento
    Description: 3.6. Fisica del vulcanismo
    Description: reserved
    Keywords: Stromboli ; SO2 Flux ; Magma column ; Infrasound ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 29
    Publication Date: 2017-04-04
    Description: Repeated phenomena of flank instability accompanied the 28 December 2002 to 21 July 2003 eruption of Stromboli volcano. The major episodes were two tsunamigenic landslides on 30 December 2002, 2 d after the volcano unrest. After 30 December, sliding processes remodeled the area affected by slope instability.We propose analyses of 565 sliding episodes taking place from December 2002 to February 2003.We try to shed light on their main seismic features and links with the ongoing seismic and volcanic activity using variogram analysis as well. A characterization of the seismic signals in the time and frequency domains is presented for 185 sliding episodes. Their frequency content is between 1 Hz and 7 Hz. On the basis of the dominant peaks and shape of the spectrum, we identify three subclasses of signals, one of which has significant energy below 2 Hz. Low-frequency signatures were also found in the seismic records of the landslides of 30 December, which affected the aerial and submarine northwestern flank of the volcano. Accordingly, we surmise that spectral analysis might provide evidence of sliding phenomena with submarine runouts.We find no evidence of sliding processes induced by earthquakes. Additionally, a negative statistical correlation between sliding episodes and explosion quakes is highlighted by variogram analysis. Variograms indicate a persistent behavior, memory, of the flank instability from 5 to 10 d.We interpret the climax in the occurrence rate of the sliding processes between 24 and 29 January 2003 as the result of favorable conditions to slope instability due to the emplacement of NW-SE aligned, dike-fed vents located near the scarp of the landslide area. Afterward, the stabilizing effect of the lava flows over the northwestern flank of the volcano limited erosive phenomena to the unstable, loose slope not covered by lava.
    Description: This work was supported financially by Istituto Nazionale di Geofisica e Vulcanologia and Dipartimento per la Protezione Civile, project INGV-DPC V4/02.
    Description: Published
    Description: Q04022
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: rockfalls ; seismicity ; volcanoes ; volcano collapses ; Stromboli ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.07. Tectonophysics::04.07.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 30
    Publication Date: 2017-04-04
    Description: We applied the Multi-GAS technique to measure compositions of the volcanic plumes continuously discharged from summit craters of Voragine, Northeast and Bocca Nuova at Mount Etna, in an attempt to estimate compositions of the source volcanic gases. The estimated CO2/SO2 and H2O/CO2 ratios of the volcanic gases show a large variation ranging from 0.6 to 30 and from 1 to 18, respectively. This variability overlaps with the compositional range of dissolved volatiles in melt inclusions and their coexisting bubbles in a magma chamber and can be caused by the low-pressure degassing of a magma with variable bubble content ranging from 0.3 to 15 wt.%. The variable bubble content in the magma is likely a result of supply of deep-derived CO2-rich gas phase to the chamber and subsequent bubble-magma differentiation by bubble ascent in the magma chamber. In contrast, the variation of volcanic gas composition can also be caused by changes of degassing pressure (gas–magma separation pressure), ranging from 0 to 100 MPa, as a result of changes in the depth of the top of the convecting magma in volcanic conduits. Both mechanisms can cause similar compositional variations. However, the two mechanisms will result in contrasting correlations between the SO2 emission rates and the gas compositions that can be examined by parallel observations of the emission rates and compositions in the future.
    Description: Published
    Description: B09203
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: 4.5. Degassamento naturale
    Description: JCR Journal
    Description: reserved
    Keywords: Plume ; gas ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 31
    Publication Date: 2017-04-04
    Description: We report the first measurements of volcanic gases with an unmanned aerial vehicle (UAV). The data were collected at La Fossa crater, Vulcano, Italy, during April 2007, with a helicopter UAV of 3 kg payload, carrying an ultraviolet spectrometer for remotely sensing the SO2 flux (8.5 Mg d 1), and an infrared spectrometer, and electrochemical sensor assembly for measuring the plume CO2/SO2 ratio; by multiplying these data we compute a CO2 flux of 170 Mg d 1. Given the deeper exsolution of carbon dioxide from magma, and its lower solubility in hydro-thermal systems, relative to SO2, the ability to remotely measure CO2 fluxes is significant, with promise to provide more profound geochemical insights, and earlier eruption forecasts, than possible with SO2 fluxes alone: the most ubiquitous current source of remotely sensed volcanic gas data.
    Description: Published
    Description: L06303
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Plume measurements ; carbon dioxide fluxes ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 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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  • 32
    Publication Date: 2017-04-04
    Description: This study presents baseline data for future geochemical monitoring of the active Tacaná volcano–hydrothermal system (Mexico–Guatemala). Seven groups of thermal springs, related to a NW/SE-oriented fault scarp cutting the summit area (4,100m a.s.l.), discharge at the northwest foot of the volcano (1,500–2,000m a.s.l.); another one on the southern ends of Tacaná (La Calera). The near-neutral (pH from 5.8 to 6.9) thermal (T from 25.7°C to 63.0°C) HCO3–SO4 waters are thought to have formed by the absorption of a H2S/SO2–CO2-enriched steam into a Cl-rich geothermal aquifer, afterwards mixed by Na/HCO3-enriched meteoric waters originating from the higher elevations of the volcano as stated by the isotopic composition (δD and δ18O) of meteoric and spring waters. Boiling temperature fumaroles (89°C at~3,600m a.s.l. NW of the summit), formed after the May 1986 phreatic explosion, emit isotopically light vapour (δD and δ18O as low as −128 and −19.9‰, respectively) resulting from steam separation from the summit aquifer. Fumarolic as well as bubbling gases at five springs are CO2-dominated. The δ13CCO2 for all gases show typical magmatic values of −3.6 ± 1.3‰ vs V-PDB. The large range in 3He/4He ratios for bubbling, dissolved and fumarolic gases [from 1.3 to 6.9 atmospheric 3He/4He ratio (RA)] is ascribed to a different degree of near-surface boiling processes inside a heterogeneous aquifer at the contact between the volcanic edifice and the crystalline basement (4He source). Tacaná volcano offers a unique opportunity to give insight into shallow hydrothermal and deep magmatic processes affecting the CO2/3He ratio of gases: bubbling springs with lower gas/water ratios show higher 3He/4He ratios and consequently lower CO2/3He ratios (e.g. Zarco spring). Typical Central American CO2/3He and 3He/4He ratios are found for the fumarolic Agua Caliente and Zarco gases (3.1 ± 1.6 × 1010 and 6.0 ± 0.9 RA, respectively). The L/S (5.9 ± 0.5)and (L + S)/M ratios (9.2 ± 0.7) for the same gases are almost identical to the ones calculated for gases in El Salvador, suggesting an enhanced slab contribution as far as the northern extreme of the Central American Volcanic Arc,Tacana
    Description: In press
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: 2.4. TTC - Laboratori di geochimica dei fluidi
    Description: JCR Journal
    Description: reserved
    Keywords: Tacaná volcano ; Fluid geochemistry ; Volcano–hydrothermal system ; Bubbling gases ; Fumaroles ; Isotopes ; Volcanic surveillance ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data
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  • 33
    Publication Date: 2017-04-04
    Description: Photogrammetric surveys were performed between 5 January and 26 July 2003 for monitoring the NW flank of the Sciara del Fuoco (SdF) during the eruption of Stromboli that started on 28 December 2002. The collected data were used both for controlling morphological changes after the major landslide that occurred on 30 December 2002 and lava flow field evolution until the end of the eruption (22 July 2003). The latter objective was achieved by a quantitative analysis which allowed to estimate the total lava volume (12.51 × 106 m3) emplaced on the SdF slope corresponding to an eruption rate of about 0.69 m3/s. Thanks to the availability of multitemporal data set, which made this event the first well-documented and regularly surveyed Stromboli eruption, the cumulative volume and effusion rate trends were derived. A model for interpreting the behavior of the 2002–2003 Stromboli effusive eruption is also proposed: being the vents located very close to the volcano summit, a typical summit (terminal) basaltic lava flow eruption was expected; on the contrary, the observed effusion rate trend showed an initial peak followed by an exponential decline typical of flank (lateral) eruptions of basaltic volcanoes. We recognized in this trend a transition from a terminal (open conduit system) to a lateral (pressurized dike system) lava discharge followed by a longer period in which the elastic strain energy from the subvolcanic reservoir controlled the effusion rate; this effect counterbalanced the lava cooling at dike tip that tends to close the eruptive fissure causing the eruption end.
    Description: Published
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: reserved
    Keywords: Stromboli ; Digital photogrammetry survey ; lava disharge mechanism ; morphological changes ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 34
    Publication Date: 2017-04-04
    Description: The 2002–2003 Etna eruption is studied through earthquake distributions and surface fracturing. In September 2002, earthquake-induced surface rupture (sinistral offset 0.48 m) occurred along the E-W striking Pernicana Fault (PF), on the NE flank. In late October, a flank eruption accompanied further ( 0.77 m) surface rupturing, reaching a total sinistral offset of 1.25 m; the deformation then propagated for 18 km eastwards to the coastline (sinistral offset 0.03 m) and southwards, along the NW-SE striking Timpe (dextral offset 0.04 m) and, later, Trecastagni faults (dextral offset 0.035 m). Seismicity (〈4 km bsl) on the E flank accompanied surface fracturing: fault plane solutions indicate an overall ESEWNWextension direction, consistent with ESE slip of the E flank also revealed by ground fractures. A three-stage model of flank slip is proposed: inception (September earthquake), climax (accelerated slip and eruption) and propagation (E and S migration of the deformation).
    Description: Published
    Description: 2286
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.2. Tettonica attiva
    Description: 3.5. Geologia e storia dei sistemi vulcanici
    Description: 3.6. Fisica del vulcanismo
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: reserved
    Keywords: volcano seismology ; surface fracturing ; flank slip ; eruption ; Etna ; 04. Solid Earth::04.01. Earth Interior::04.01.99. General or miscellaneous ; 04. Solid Earth::04.01. Earth Interior::04.01.02. Geological and geophysical evidences of deep processes ; 04. Solid Earth::04.02. Exploration geophysics::04.02.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous ; 04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution ; 04. Solid Earth::04.06. Seismology::04.06.02. Earthquake interactions and probability ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk ; 04. Solid Earth::04.07. Tectonophysics::04.07.99. General or miscellaneous ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 35
    Publication Date: 2017-04-04
    Description: During the onset of 2008 volcanic crisis at Mt Etna, the near-real time magnetic data provided a continuous updating of the volcano activity state on the northern flank. On the morning of 13th May 2008, significant local magnetic field changes marked the resumption of the eruptive activity characterized by the opening of a fracture field on the northern flank, and an eruptive fissure in the Valle del Bove. In agreement with the northward propagation of seismic events, magnetic signals at 5 stations in the summit area revealed a nearly NNW-SSE oriented magmatic intrusion, which started at about 9:00 GMT, propagated northward for about 2 km, and stopped at 14:00 GMT before reaching the North-East Rift. Magnetic variations, with amplitude ranging between 1.8 nT and -6.5 nT, are consistent with those calculated from piezomagnetic models, where stress-induced changes in rock magnetization are produced by the magmatic intrusion.
    Description: Published
    Description: L22301
    Description: 2.6. TTC - Laboratorio di gravimetria, magnetismo ed elettromagnetismo in aree attive
    Description: JCR Journal
    Description: partially_open
    Keywords: Mt Etna ; volcano monitoring ; piezomagnetic field ; magmatic intrusion ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 36
    Publication Date: 2017-04-04
    Description: On two occasions, sudden gravity changes occurred simultaneously at two summit Etna’s stations, during local low-magnitude earthquakes. A systematic coupling between earthquakes inducing comparable maximum acceleration and displacement at the observation points and gravity steps is missing, implying (a) the non-instrumental nature of the steps and (b) the need for particular underlying conditions for the triggering mechanism(s) to activate. We review some of the volcanological processes that could induce fast underground mass redistributions, resulting in gravity changes at the surface. These processes involve bubbles and crystals present in the magma and require particular conditions in order to be effective as mass-redistributing processes. The gravity steps could be a geophysical evidence of the dynamical stress transfer between tectonic and magmatic systems at a local scale. Given the implications that these transfers may have on the volcanic activity, routine volcano monitoring should include the observation of fast gravity changes.
    Description: In press
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: open
    Keywords: gravity changes ; volcano ; 04. Solid Earth::04.01. Earth Interior::04.01.02. Geological and geophysical evidences of deep processes ; 04. Solid Earth::04.03. Geodesy::04.03.05. Gravity variations ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 37
    Publication Date: 2017-04-04
    Description: Two-dimensional cross sections of the sulphur dioxide (SO2) distribution in the volcanic gas plume of Mt. Etna were reconstructed using tomographic techniques. The data for these projections were generated by a network of five automated scanning spectrometers, positioned on the flanks of the volcano. These measure slant-column amounts of SO2 at 105 different angles, every four minutes. Stable wind conditions allow the plume to be monitored on 82% of days. A time-series of plume cross sections was computed, revealing the potential of this method to track variations in plume position and structure on timescales of minutes to hours, a result of potential importance for air traffic and civil defence in case of eruption, when copious amounts of fine ash can be transported.
    Description: Published
    Description: L17811
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: tomography ; SO2 ; DOAS ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
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  • 38
    Publication Date: 2020-02-24
    Description: Stromboli’s 5 April 2003 explosion sent an ash plume to 4 km and blocks to 2 km, representing one of the most powerful events over the last 100 years. A thermal sensor 450 m east of the vent and a helicopter-flown thermal camera captured the event dynamics allowing detailed reconstruction. This review links previous studies providing a complete collation and clarification of the actual event chronology, while showing how relatively inexpensive thermal sensors can be used to provide great insight into processes that cannot be observed from locations outside of the eruption cloud. The eruption progressed through four phases, comprised 29 discrete explosions and lasted 373 s. The opening phase (phase 1) comprised ~30 s of precursory ash emission, with stronger emission beginning after 17 s. This was abruptly terminated by the main blast of phase 2 which comprised emission of a rapidly expanding ash cloud followed, after 0.4 s, by a powerful jet with velocities of up to 320 m/s. A second explosive phase (phase 3) began 38 s later and involved ascent of a phoenix cloud and explosive emission above a lateral vent lasting 75 s. This was followed by a 175-s-long phase of weaker, pulsed emission. The eruption was terminated by a series of three explosions (phase 4) sending ash to ~600 m at velocities of 27-45 m/s and lasting 87 s. Together these results have shown that a low energy opening phase was followed by the highest energy phase. Each phase itself comprised groups of discrete explosions, with energy of the explosions diminishing during the two final phases.
    Description: Published
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: open
    Keywords: Thermal imaging ; Stromboli ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 39
    Publication Date: 2020-02-24
    Description: Regular surveys with a PM695 FLIR thermal imaging camera from both the ground and from helicopter were conducted on Stromboli from October 2001. These measurements allow us to (i) examine changes in morphology of the summit craters produced by paroxystic explosions and (ii) track the increasing level of magma within the conduits of Stromboli that preceded and led to the 2002/03 effusive eruption. Two geophysical surveys in May and September/October 2002 demonstrated a clear increasing trend in the amplitude of VLP events, consistent with the presence of a higher magma column above the VLP source region. The observed increase in magma level was probably induced by an increase in the pressure of the magma feeding system at Stromboli, controlled by regional tectonic stress. The increased magma level induced strain on the uppermost part of the crater terrace, allowing an increase in soil permeability and therefore CO2 and Radon degassing. Eventually this stress caused the northeast flank of the craters to fracture, allowing lava to flood out at high effusion rates on 28th December. Regular surveys with the thermal imaging camera, combined with geophysical monitoring, are an invaluable addition to the armory of volcanologists attempting to follow the evolution of activity on active volcanoes.
    Description: Published
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: open
    Keywords: Thermal imaging ; Stromboli ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 40
    Publication Date: 2020-02-24
    Description: At 18:20 of 28 December 2002 an eruptive vent opened on the NE flank of the Sciara del Fuoco at 600 m asl, marking the onset of the 2002-2003 eruptive crisis of Stromboli volcano. The first eruptive hours were characterized by mild spattering and effusive activity from the new vent and the summit vent at crater 1. Gravitational instability processes also determined the partial collapse of NE walls of the summit cone (crater 1). Pyroclastic material partly accumulated on the NE part of the Sciara, and partly flowed down slope and reached the sea at Spiaggia dei Gabbiani forming a ~ 4m-thick, reddish avalanche, that was soon covered by a lava flow emitted in the following hours (Lodato et al., 2007). In this paper, we describe the first hours of activity trough eyewitnesses’ reports, geophysical monitoring, field and laboratory studies and of the erupted pyroclastic material and lava flows. Daily temperature measurements were carried out on the avalanche deposit formed by the flow of scoria along the Sciara, using a handheld thermal camera mainly during helicopter surveys. A fast cooling rate was typical of the deposit surface, and a slow cooling rate was representative of its inner portion.
    Description: Published
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: open
    Keywords: Thermal imaging ; Stromboli ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 41
    Publication Date: 2020-02-24
    Description: On 28 December 2002, an effusive flank eruption started at Stromboli volcano (Aeolian Islands, 15 Italy). This lasted until 22 July 2003 and produced two lava flow fields that were emplaced onto the 16 steep slopes of Sciara del Fuoco. The first flow field was fed by a vent that opened at 500 m 17 elevation and was active between 30 December 2002 and 15 February 2003. The second was 18 supplied by a vent at 670 m and was emplaced mainly between 15 February and 22 July 2003. Here 19 we review the lava flow field emplacement based on daily thermal and visual surveys. The variable 20 slopes on which the lava flowed yielded an uncommon flow field morphology. This resulted in a 21 lava shield in the proximal area where flow stacking and inflation caused piling up of lava due to the 22 relatively flat ground. The proximal area was characterized by a complex network of tumuli and 23 tube-fed flows associated. The medial-distal lava flow field was emplaced on an extremely steep 24 zone. This area showed persistent flow front crumbling, producing a debris field on which emplaced 25 lava flows formed lava channels with excavated debris levées. This eruption provided an exceptional 26 opportunity to examine the evolution of lava flow fields emplaced on steep slopes, and proved the 27 usefulness of thermal imagers for safe and efficient monitoring of the active lava flows. In addition, thermal monitoring allowed calculation of quantitative parameters, such as effusion rate, allowing constraint of the time varying nature of supply to this eruption.
    Description: Published
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: open
    Keywords: thermal imaging ; stromboli ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 42
    Publication Date: 2020-02-24
    Description: Measurements of 220Rn and 222Rn activity and of CO2 flux in soil and fumaroles were carried out on Mount Etna volcano in 2005–2006, both in its summit area and along active faults on its flanks. We observe an empirical relationship between (220Rn/222Rn) and CO2 efflux. The higher the flux of CO2, the lower the ratio between 220Rn and 222Rn. Deep sources of gas are characterized by high 222Rn activity and high CO2 efflux, whereas shallow sources are indicated by high 220Rn activity and relatively low CO2 efflux. Excess 220Rn highlights sites of ongoing shallow rock fracturing that could be affected by collapse, as in the case of the rim of an active vent. Depletion both in 220Rn and in CO2 seems to be representative of residual degassing along recently active eruptive vents.
    Description: This work was funded by the Istituto Nazionale di Geofisica e Vulcanologia (S.G., M.N.) and by the Dipartimento per la Protezione Civile (Italy), projects V3_6/28-Etna (M.N.) and V5/08-Diffuse degassing in Italy (S.G.), and NSF EAR 063824101 (K.W.W.S.).
    Description: Published
    Description: Q10001
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: 4.5. Degassamento naturale
    Description: JCR Journal
    Description: reserved
    Keywords: radon ; thoron ; carbon dioxide ; rock stress ; gas transport ; Mount Etna ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data
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  • 43
    Publication Date: 2018-02-01
    Description: This paper reviews the published geochemical variations observed during the 2002–2003 eruption at Stromboli volcano. At the end of 2002, a new eruption began at Stromboli with a lava flow that lasted until the end of July 2003. On 5 April 2003 an explosive paroxysm occurred with the ejection of bombs that reached the village of Ginostra, about 4 km from the craters. During the eruption, specific variations in chemical composition of ground waters and summit fumaroles were recorded before the explosion, most of them for the first time. The water pH decreased significantly (0.5 units) and the dissolved CO2 increased in two thermal wells (Cusolito and Zurro) located near Stromboli harbor from March until 5 April. Peaks in the dissolved He were also observed at all the sampling sites. All of these changes in the thermal aquifer suggested a pressurization of the system due to the degassing of a volatile-rich magma at depth. In the summit area the SO2/HCl and SO2/HF ratios in the plume increased suddenly between 1 and 3 April due to the degassing of an S-rich magma that was approaching the shallow levels of the plumbing system, and this was involved in the explosion that occurred a few days later. This eruption was the first at Stromboli to be analyzed using geochemical models. The variations observed in the basal aquifer and in the summit area occurred on very different timescales: a few weeks and few days, respectively.
    Description: Published
    Description: 347-358
    Description: 2V. Struttura e sistema di alimentazione dei vulcani
    Description: open
    Keywords: paroxysm ; geochemical observations ; monitoring ; plume ; thermal aquifer ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 44
    Publication Date: 2017-04-04
    Description: Measurement of effusion rate is a primary objective for studies that model lava flow and magma system dynamics, as well as for monitoring efforts during on-going eruptions. However, its exact definition remains a source of confusion, and problems occur when comparing volume flux values that are averaged over different time periods or spatial scales, or measured using different approaches. Thus our aims are to: (1) define effusion rate terminology; and (2) assess the various measurement methods and their results. We first distinguish between instantaneous effusion rate, and time-averaged discharge rate. Eruption rate is next defined as the total volume of lava emplaced since the beginning of the eruption divided by the time since the eruption began. The ultimate extension of this is mean output rate, this being the final volume of erupted lava divided by total eruption duration. Whether these values are total values, i.e. the flux feeding all flow units across the entire flow field, or local, i.e. the flux feeding a single active unit within a flow field across which many units are active, also needs to be specified. No approach is without its problems, and all can have large error (up to ∼50%). However, good agreement between diverse approaches shows that reliable estimates can be made if each approach is applied carefully and takes into account the caveats we detail here. There are three important factors to consider and state when measuring, giving or using an effusion rate. First, the time-period over which the value was averaged; second, whether the measurement applies to the entire active flow field, or a single lava flow within that field; and third, the measurement technique and its accompanying assumptions.
    Description: Published
    Description: 1-22
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: JCR Journal
    Description: reserved
    Keywords: Lava ; Instantaneous effusion rate ; Time-averaged discharge rate ; Eruption rate ; Monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
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  • 45
    Publication Date: 2017-04-04
    Description: Soil temperature and total dissolved gas pressure(TDGP) data were recorded by two continuous monitoring stations on the volcano of Stromboli (Italy) between March and October 2006. During this period several TDGP and soil temperature anomalies, unrelated to external causes and characterized by a similar shape and occurrence time, were recorded. These anomalies were interpreted as transients due to changes in the degassing regime of the volcano,which was in turn related to changes in the partition ratio of the volcanic fluidsbetweenthe conduitandthe soil. In thesame period Stromboli experienced an anomalous phase of volcanic and tectonic activity. The close correlation found between volcano-tectonic activity and variations in anomalousmonitored parameters suggests that their continuous monitoring may be a useful tool for the surveillance of volcanic activity on the island.
    Description: Published
    Description: L08301
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Dissolved gases ; Soil temperature ; Total dissolved gas pressure ; Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 46
    Publication Date: 2017-04-03
    Description: Soil-temperature measurements can provide information on the distribution of degassing fissures, their relationship to the internal structure of the volcano, and the temporal evolution of the system. At Vulcano Island (Italy) heat flux from a 〈3 km-deep magma body drives a hydrothermal system which extends across the main Fossa crater. This heat flux is also associated with variable magmatic gas flow. A high density map of soil-temperatures was made in 1996 at a constant depth of 30 cm on the central and southern inner flanks of the Fossa crater. These measurements extended over an area covering about 0.04 km2, across which the heat flux is predominantly associated with a shallow boiling aquifer. The map shows that hot zones relate to structures of higher permeability, mainly associated with a fissure system dating from the last eruptive cycle (1888-90). From 1996 to January 2005, we studied the evolution of the heat flux for the high temperature part of the map, both by repeating our measurements as part of fourteen visits, during which temperatures were measured at a constant depth, and using data from permanent stations which allowed soil-temperatures to be continuously measured for selected vertical profiles. These data allowed us to calculate the heat flux, and its variation, with good precision for values lower than about 100 W m-2, which is generally the case in the study area. Above 100 W m-2 although the heat flux value is underestimated its variations are recorded with an error less than 10%. During the period 1996-2004 two increases in the thermal flux were recorded. The first one was related to the seismic crisis of November 1998 which opened existing or new fissures. The second, in November 2004, was probably due to magma migration, and was associated with minor seismic activity.
    Description: Published
    Description: on line first
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: JCR Journal
    Description: partially_open
    Keywords: hydrothermal flux ; soil temperature ; monitoring ; seismic activity ; Vulcano ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 47
    Publication Date: 2017-04-04
    Description: Measuring Hg/SO2 ratios in volcanic emissions is essential for better apportioning the volcanic contribution to the global Hg atmospheric cycle. Here, we report the first real-time simultaneous measurement Hg and SO2 in a volcanic plume, based on Lumex and MultiGAS techniques, respectively. We demonstrate that the use of these novel techniques allows the measurements of Hg/SO2 ratios with a far better time resolution than possible with more conventional methods. The Hg/SO2 ratios in the plume of F0 fumarole on La Fossa Crater, Vulcano Island spanned an order of magnitude over a 30 minute monitoring period, but was on average in qualitative agreement with the Hg/SO2 ratio directly measured in the fumarole (mean plume and fumarole ratios being 1.09 x 10-6 and 2.9 x 10-6, respectively). The factor 2 difference between plume and fumarole compositions provides evidence for fast Hg chemical processing the plume.
    Description: Published
    Description: L21307
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: JCR Journal
    Description: partially_open
    Keywords: Mercury ; Fumarolic condensates ; Volcanic emissions ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 48
    Publication Date: 2017-04-04
    Description: The Southeast Crater of Mount Etna (Italy) was characterized by a violent eruptive activity between 26 January and 24 June 2000. This activity produced 64 lava fountain episodes with repose periods from 3 hours to 10 days. We estimated a volume of about 15–20 106 m3 lava and at least 2–3 106 m3 of tephra. We compared the paroxysmal volcanic activity to its associated seismic signature: The high number of events highlighted a strict correlation between tremor and volcanic activity. Seismic and volcanic characteristics, such as the frequency of occurrence, the duration of lava fountains and the associated tremor energy, suggested the subdivision of the studied period into two stages separated by the 20 February event. Combining volcanic with seismic data, we observed some useful relationships among lava fountain height, sustained column height and Reduced Displacement; in addition, we found that the entire episode was well correlated with the duration of the amplitude increase. Computing the tremor energy linked to each event, the total energy associated with lava fountains episodes results in 76% of the energy released during the whole period. Finally, the different ratios among the overall spectral amplitude of the seismic signals of the stations located at different altitudes suggested to us the elaboration of a simple qualitative model to explain the dynamic behavior of the tremor source during the whole episode.
    Description: Published
    Description: open
    Keywords: Mount Etna ; lava fountain ; volcanic tremor ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 49
    Publication Date: 2017-04-04
    Description: Every month, small-scale explosive volcanic eruptions inject more than a million cubic meters of ash into Earth’s atmosphere [Simkin and Siebert, 2000]. Of all the troubles caused by this relatively mild volcanic activity, ashfall is by far the longest-reaching one, mantling the volcano slopes and surroundings with a slippery, heavy, unhealthy, and snow-like but Sun-resistant cover. Volcanic ash is composed of pyroclasts (fragments generated and emplaced by explosive eruptions) smaller than 2 millimeters, which are easily transported by wind and have a high surface-to-volume ratio. These same features, however, also allow safe collection of the ash away from the volcano. Such pyroclasts bear the signature of the fragmentation and dispersal processes they have experienced during eruption and transport. Thus, volcanic ash provides sample material well suited for studying quasi time correlated eruption dynamics [Taddeucci et al., 2002]. Here we illustrate how current research projects funded by the Italian Department for Civil Protection combine new sampling, analytical, and experimental techniques to maximize the extraction of useful information from basaltic volcanic ash.
    Description: Published
    Description: 253–260
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: N/A or not JCR
    Description: reserved
    Keywords: Volcanic ; ash ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 50
    Publication Date: 2017-04-04
    Description: On 22 September 2002, 1 month before the beginning of the flank eruption on the NE Rift, an M-3.7 earthquake struck the northeastern part of Mt. Etna, on the westernmost part of the Pernicana fault. In order to investigate the ground deformation pattern associated with this event, a multi-disciplinary approach is presented here. Just after the earthquake, specific GPS surveys were carried out on two small sub-networks, aimed at monitoring the eastern part of the Pernicana fault, and some baselines belonging to the northeastern EDM monitoring network of Mt. Etna were measured. The leveling route on the northeastern flank of the volcano was also surveyed. Furthermore, an investigation using SAR interferometry was performed and also the continuous tilt data recorded at a high precision sensor close to the epicenter were analyzed to constrain the coseismic deformation. The results of the geodetic surveys show a ground deformation pattern that affects the entire northeastern flank of the volcano, clearly shaped by the Pernicana fault, but too strong and wide to be related only to an M-3.7 earthquake. Leveling and DInSAR data highlight a local strong subsidence, up to 7 cm, close to the Pernicana fault. Significant displacements, up to 2 cm, were also detected on the upper part of the NE Rift and in the summit craters area, while the displacements decrease at lower altitude, suggesting that the dislocation did not continue further eastward. Three-dimensional GPS data inversions have been attempted in order to model the ground deformation source and its relationship with the volcano plumbing system. The model has also been constrained by vertical displacements measured by the leveling survey and by the deformation map obtained by SAR interferometry.
    Description: Published
    Description: 757-768
    Description: 1.3. TTC - Sorveglianza geodetica delle aree vulcaniche attive
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: partially_open
    Keywords: Ground deformation ; Modeling ; Flank dynamics ; Volcano-tectonics ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations ; 04. Solid Earth::04.03. Geodesy::04.03.06. Measurements and monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 51
    Publication Date: 2017-04-04
    Description: The use of a hand-held thermal camera during the 2002–2003 Stromboli effusive eruption proved essential in tracking the development of flow field structures and in measuring related eruption parameters, such as the number of active vents and flow lengths. The steep underlying slope on which the flow field was emplaced resulted in a characteristic flow field morphology. This comprised a proximal shield, where flow stacking and inflation caused piling up of lava on the relatively flat ground of the vent zone, that fed a medial–distal lava flow field. This zone was characterized by the formation of lava tubes and tumuli forming a complex network of tumuli and flows linked by tubes. Most of the flow field was emplaced on extremely steep slopes and this had two effects. It caused flows to slide, as well as flow, and flow fronts to fail frequently, persistent flow front crumbling resulted in the production of an extensive debris field. Channel-fed flows were also characterized by development of excavated debris levees in this zone (Calvari et al. 2005). Collapse of lava flow fronts and inflation of the upper proximal lava shield made volume calculation very difficult. Comparison of the final field volume with that expecta by integrating the lava effusion rates through time suggests a loss of ~70% erupted lava by flow front crumbling and accumulation as debris flows below sea level. Derived relationships between effusion rate, flow length, and number of active vents showed systematic and correlated variations with time where spreading of volume between numerous flows caused an otherwise good correlation between effusion rate, flow length to break down. Observations collected during this eruption are useful in helping to understand lava flow processes on steep slopes, as well as in interpreting old lava–debris sequences found in other steep-sided volcanoes subject to effusive activity.
    Description: Published
    Description: JCR Journal
    Description: reserved
    Keywords: Lava flow field ; Morphology ; Tumuli ; Lava tubes ; Effusion rate ; Rheology ; Stromboli volcano ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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  • 52
    Publication Date: 2017-04-04
    Description: Bulk atmospheric deposition of major cations (Na, K, Ca, Mg) and anions (Cl, F, SO4) were measured at 15 sites around an active volcano, Mount Etna, from 2001 to 2003. Their composition indicates several natural sources, among which deposition of plume-derived volcanogenic gas compounds is prevalent for F, Cl and S. Plume-derived acidic compounds are also responsible for the prevailing acidic composition of the samples collected on the summit of the volcano (pH in the 2.45–5.57 range). Cation species have complex origin, including deposition of plume volcanogenic ash and aerosols and soil-dust wind re-suspension of either volcanic or carbonate sedimentary rocks. Variation of the deposition rates during the March 2001– March 2003 period, coupled with previous measurements from 1997 to 2000 (Appl Geochem 16:985–1000, 2001), were compared with the variation of SO2 flux, volcanic activity and rainfall. The deposition rate was mainly controlled by rainfall. Commonly, about 0.1–0.9% of HF, HCl and SO2 emitted by the summit crater’s plume were deposited around the volcano. We estimate that ∼2 Gg of volcanogenic sulphur were deposited over the Etnean area during the 2002–2003 flank eruption, at an average rate of ∼24 Mg day−1 which is two orders of magnitude higher than that typical of quiescent degassing phases.
    Description: Published
    Description: 255-265
    Description: JCR Journal
    Description: open
    Keywords: Volcanic degassing ; Etna volcano ; Impact of volcanic eruptions ; S deposition rates ; Halogen deposition rates ; Bulk deposition chemistry ; Environmental volcanology ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 53
    Publication Date: 2017-04-04
    Description: Forward Looking Infrared Radiometer (FLIR) cameras offer a unique view of explosive volcanism by providing an image of calibrated temperatures. In this study, 344 eruptive events at Stromboli volcano, Italy, were imaged in 2001–2004 with a FLIR camera operating at up to 30 Hz. The FLIR was effective at revealing both ash plumes and coarse ballistic scoria, and a wide range of eruption styles was recorded. Eruptions at Stromboli can generally be classified into two groups: Type 1 eruptions, which are dominated by coarse ballistic particles, and Type 2 eruptions, which consist of an optically-thick, ash-rich plume, with (Type 2a) or without (Type 2b) large numbers of ballistic particles. Furthermore, Type 2a plumes exhibited gas thrust velocities (〉15 m s−1) while Type 2b plumes were limited to buoyant velocities (〈15 m s−1) above the crater rim. A given vent would normally maintain a particular gross eruption style (Type 1 vs. 2) for days to weeks, indicating stability of the uppermost conduit on these timescales. Velocities at the crater rim had a range of 3–101 m s−1, with an overall mean value of 24 m s−1. Mean crater rim velocities by eruption style were: Type 1= 34 m s−1, Type 2a=31 m s−1, Type 2b=7 m s−1. Eruption durations had a range of 6–41 s, with a mean of 15 s, similar among eruption styles. The ash in Type 2 eruptions originates from either backfilled material (crater wall slumping or ejecta rollback) or rheological changes in the uppermost magma column. Type 2a and 2b behaviors are shown to be a function of the overpressure of the bursting slug. In general, our imaging data support a broadening of the current paradigm for strombolian behavior, incorporating an uppermost conduit that can be more variable than is commonly considered.
    Description: NSF grant no. EAR-0207734, NERC grant no. NER/B/S/2001/00707, the USGS Volcano Hazards Program and the Geophysical Institute at the University of Alaska Fairbanks
    Description: Published
    Description: 769-784
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: JCR Journal
    Description: reserved
    Keywords: Stromboli volcano ; volcano monitoring ; thermal imaging ; eruption dynamics ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 54
    Publication Date: 2017-04-04
    Description: Sulphur speciation in volcanic gases acts as a major redox buffer, and H2S/SO2 ratios represent a valuable indicator of magmatic conditions and interactions between magmatic and hydrothermal fluids. However, measurement of H2S/SO2 even by direct sampling techniques, is not straightforward. We report here on application of a small ultraviolet spectrometer for real-time field measurement of H2S and SO2 concentrations, using open-path and extractive configurations. The device was tested at fumaroles on Solfatara and Vulcano, Italy, in November 2002. H2S concentrations of up to 220ppmm(400 ppmv) were measured directly above the Bocca Grande fumarole at Solfatara, and H2S/SO2 molar ratios of 2 and 2.4, respectively, were determined for the ‘F11’ and ‘F0’ fumaroles at Vulcano. In comparison with other optical techniques capable of multiple volcanic gas measurements, such as laser and FTIR spectroscopy, this approach is considerably simpler and cheaper, with the potential for autonomous, sustained hightime resolution operation.
    Description: Published
    Description: 1652
    Description: partially_open
    Keywords: Remote monitoring ; Plume chemistry ; sulphur species ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
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  • 55
    Publication Date: 2017-04-04
    Description: In this paper we provide a review of chemical and isotopic data gathered over the last three decades on Etna volcano's fluid emissions and we present a synthetic framework of their spatial and temporal relationships with the volcano-tectonic structures, groundwater circulation and eruptive activity. We show that the chemistry, intensity and spatial distribution of gas exhalations are strongly controlled by the main volcano-tectonic fault systems. The emission of mantle-derived magmatic volatiles, supplied by deep to shallow degassing of alkali-hawaiitic basalts, persistently occurs through the central conduits, producing a huge volcanic plume. The magmatic derivation of the hot gases is verified by their He, C and S isotopic ratios. Colder but widespread emanations of magma-derived CO2 and He also occur through the flanks of the volcano and through aquifers, mainly concentrated within two sectors of the south-southwest (Paternò-Belpasso) and eastern (Zafferana) flanks. In these two peripheral areas, characterized by intense local seismicity and gravity highs, magma-derived CO2 and helium are variably diluted by shallower crustal-derived fluids (organically-derived carbon, radiogenic helium). Thermal and geochemical anomalies recorded in groundwaters and soil gases within these two areas prior to the 1991-1993 eruption are consistent with an input of hot fluids released by ascending magma. Magmatic fluids interacted with the shallow aquifers, modifying their physico-chemical conditions, and led to strong variations of the soil CO2 flux. In addition to routine survey of the crater plume emissions, geochemical monitoring of remote soil gases and groundwaters may thus contribute to forecasting Etna's eruptions.
    Description: Published
    Description: 129-145
    Description: partially_open
    Keywords: Mt. Etna ; Geochemical surveillance ; Groundwaters ; Volcanic gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 56
    Publication Date: 2017-04-04
    Description: The recent eruption of Mount Etna (July 2001) offered the opportunity to analyze magma-derived volatiles emitted during preand syn-eruptive phases, and to verify whether their composition is affected by changes in volcanic dynamics. This paper presents the results of analyses of F, Cl and S in the volcanic plume collected by filter-packs, and interprets variations in the composition based on contrasting solubility in magmas. A Rayleigh-type degassing mechanism was used to fit the acquired data and to estimate Henryâ s solubility constant ratios in Etnean basalt. This model provided insights into the dynamics of the volcano. Abundances of sulfur and halogens in eruptive plumes may help predict the temporal evolution of an ongoing effusive eruption.
    Description: -Gruppo Nazionale per la Vulcanologia.
    Description: Published
    Description: 1559
    Description: partially_open
    Keywords: magmatic degassing ; acidic gases ; plume chemistry ; 01. Atmosphere::01.01. Atmosphere::01.01.07. Volcanic effects ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 57
    Publication Date: 2017-04-04
    Description: Volcanic gas emissions from fumaroles on the rim of La Fossa crater, Vulcano Island, Italy, were measured simultaneously using direct sampling (for H2O, CO2, total sulfur, HCl and HF), filter packs (for SO2, HCl, HF) and short-path active-mode FTIR measurements (for H2O, CO2,SO2, HCl and HF) in an intercomparison study in May 2002. The results show that Cl/F ratios were in good agreement between all three methods, and that FTIR and direct sampling determined comparable proportions of CO2 and H2O. Amounts of total S observed in direct sampling data were approximately double the amounts of SO2 measured with filter packs and FTIR. This difference could be attributed either to the fact FTIR and filter packs do not measure reduced sulfur species (e.g., H2S) or to sublimation of elemental S upon exit from the fumarole, after collection by direct sampling but before detection with FTIR and filter packs.
    Description: Published
    Description: L02610
    Description: partially_open
    Keywords: volcanic gas techniques ; gas geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
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  • 58
    Publication Date: 2017-04-04
    Description: Ground deformation occurring on the southern flank of Mt Etna volcano during the JulyAugust 2001 eruption was monitored by GPS measurements along an EW profile crossing the fissure system. This profile was measured eight times during the eruption, using the 'stop and go' semi-kinematic technique. Horizontal and vertical displacements between GPS surveys are reported for each station. The most significant event is a deformation episode occurring during the first week of the eruption, between 2527 July. Displacements were measured on benchmarks close to the eruptive fissure and the tensile 1989 fracture. Data inversions for measured displacements were performed using the Okada model. The model shows the narrowing of the 2001 dyke accompanied by a dextral dislocation along an east-dipping fault, parallel to the 1989 fracture.
    Description: Published
    Description: 336-341
    Description: partially_open
    Keywords: GPS ; Ground deformation ; Modelling ; Volcano monitoring ; 04. Solid Earth::04.03. Geodesy::04.03.07. Satellite geodesy ; 04. Solid Earth::04.03. Geodesy::04.03.09. Instruments and techniques ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 59
    Publication Date: 2017-04-04
    Description: The 200203 Mt Etna flank eruption began on 26 October 2002 and finished on 28 January 2003, after three months of continuous explosive activity and discontinuous lava flow output. The eruption involved the opening of eruptive fissures on the NE and S flanks of the volcano, with lava flow output and fire fountaining until 5 November. After this date, the eruption continued exclusively on the S flank, with continuous explosive activity and lava flows active between 13 November and 28 January 2003. Multi-disciplinary data collected during the eruption (petrology, analyses of ash components, gas geochemistry, field surveys, thermal mapping and structural surveys) allowed us to analyse the dynamics of the eruption. The eruption was triggered either by (i) accumulation and eventual ascent of magma from depth or (ii) depressurisation of the edifice due to spreading of the eastern flank of the volcano. The extraordinary explosivity makes the 200203 eruption a unique event in the last 300 years, comparable only with La Montagnola 1763 and the 2001 Lower Vents eruptions. A notable feature of the eruption was also the simultaneous effusion of lavas with different composition and emplacement features. Magma erupted from the NE fissure represented the partially degassed magma fraction normally residing within the central conduits and the shallow plumbing system. The magma that erupted from the S fissure was the relatively undegassed, volatile-rich, buoyant fraction which drained the deep feeding system, bypassing the central conduits. This is typical of most Etnean eccentric eruptions. We believe that there is a high probability that Mount Etna has entered a new eruptive phase, with magma being supplied to a deep reservoir independent from the central conduit, that could periodically produce sufficient overpressure to propagate a dyke to the surface and generate further flank eruptions.
    Description: Published
    Description: 314-330
    Description: partially_open
    Keywords: Multi-disciplinary study ; Mount Etna ; 2002–03 eruption ; Eccentric eruptions ; Flank activity ; Etna feeding system ; Volcanic processes ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
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  • 60
    Publication Date: 2017-04-04
    Description: Constraining fluxes of volcanic bromine and iodine to the atmosphere is important given the significant role these species play in ozone depletion. However, very few such measurements have been made hitherto, such that global volcanic fluxes are poorly constrained. Here we extend the data set of volcanic Br and I degassing by reporting the first measurements of bromine and iodine emissions from Mount Etna. These data were obtained using filter packs and contemporaneous ultraviolet spectroscopic SO2 flux measurements, resulting in time-averaged emission rates of 0.7 kt yr 1 and 0.01 kt yr 1 for Br and I, respectively, from April to October 2004, from which we estimate global Br and I fluxes of order 13 (range, 3â 40) and 0.11 (range, 0.04â 6.6) kt yr 1. Observed changes in plume composition highlight the coherent geochemical behavior of HCl, HF, HBr, and HI during magmatic degassing, and strong fractionation of these species with respect to SO2.
    Description: Published
    Description: Q08008
    Description: partially_open
    Keywords: bromine and iodine in volcanic gases ; halogen atmospheric chemistry ; volcanic degassing ; volcanic plumes ; 01. Atmosphere::01.01. Atmosphere::01.01.07. Volcanic effects ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 61
    Publication Date: 2017-04-04
    Description: A new method for extracting dissolved gases in natural waters has been developed and tested, both in the laboratory and in the field. The sampling device consists of a polytetrafluroethylene (PTFE) tube (waterproof and gas permeable) sealed at one end and connected to a glass sample holder at the other end. The device is pre-evacuated and subsequently dipped in water, where the dissolved gases permeate through the PTFE tube until the pressure inside the system reaches equilibrium. A theoretical model describing the time variation in partial gas pressure inside a sampling device has been elaborated, combining the mass balance and ‘‘Solution-Diffusion Model’’ which describes the gas permeation process through a PTFE membrane). This theoretical model was used to predict the temporal evolution of the partial pressure of each gas species in the sampling device. The model was validated by numerous laboratory tests. The method was applied to the groundwater of Vulcano Island (southern Italy). The results suggest that the new sampling device could easily extract the dissolved gases from water in order to determine their chemical and isotopic composition.
    Description: - European Social Fund.
    Description: Published
    Description: Q09005
    Description: partially_open
    Keywords: dissolved gases ; helium isotope ; PTFE membrane ; Vulcano Island ; 03. Hydrosphere::03.02. Hydrology::03.02.04. Measurements and monitoring ; 03. Hydrosphere::03.02. Hydrology::03.02.07. Instruments and techniques ; 04. Solid Earth::04.04. Geology::04.04.11. Instruments and techniques ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
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  • 62
    Publication Date: 2017-04-04
    Description: Ground-based measurements of volcanic sulfur dioxide fluxes are important indicators of volcanic activity, with application in hazard assessment, and understanding the impacts of volcanic emissions upon the environment and climate. These data are obtained by making traverses underneath the volcanic plume a few kilometers from source with an ultraviolet spectrometer, measuring integrated SO2 concentrations across the plume’s cross section, and multiplying by the plume’s transport speed. However, plume velocities are usually derived from ground-based anemometers, located many kilometers from the traverse route and hundreds of meters below plume altitude, complicating the experimental design and introducing large flux (can be 〉100%) errors. Here we present the first report of a single instrument capable of (accurate) volcanic SO2 flux measurements. This device records integrated SO2 concentrations and plume heights during traverses. Between traverses, two in-plume SO2 time series are measured from underneath the plume with the instrument, corresponding to zenith and inclined (user-specified angle from vertical in the direction of the volcano) fields of view, respectively. The distance between the points of intersection of the two views with the plume is found on the basis of the determined plume height, and the two signals are cross-correlated to determine the lag between them, enabling accurate derivation of the wind speed. We present flux data (with errors ±12%) obtained in this way at Mt. Etna during July 2004.
    Description: Published
    Description: Q02003
    Description: partially_open
    Keywords: DOAS ; volcanic SO2 emissions. ; 01. Atmosphere::01.01. Atmosphere::01.01.07. Volcanic effects ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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  • 63
    Publication Date: 2017-04-04
    Description: This paper reports the use of diffusive tubes in determining HF, HCl, and SO2 in the volcanic plume of Mount Etna in an attempt to highlight the potential of this method in studying volcanoes. In a first application a network of 18 diffusive tubes was installed on Etna flanks, aimed at evaluating the atmospheric dispersion of the volcanic plume on a local scale. Results showed a monotonic decrease in volatile air concentrations with distance from the craters (HF from 0.15 to 〈0.003 mmol m3, HCl from 2 to 〈0.01 mmol m3, and SO2 from 11 to 0.04 mmol m3), revealing the prevalently volcanic contribution. Matching of SO2/HCl and HCl/HF volatile ratios with contemporaneous measurements at the summit craters validated the use of diffusive tubes in tracing the chemical features of a volcanic plume from remote locations. A first tentative assessment of dry deposition rates of volcanogenic acidic gases was also made, yielding 2.5 74 t d1 (SO2), 0.6 17 t d1 (HCl), and 0.02 0.6 t d1 (HF) and revealing the potential environmental impact of gas emissions. In a second experiment, carried out during the recent October 2002 to February 2003 eruption of Etna, diffusive tubes provided a continuous record of the chemical composition of the eruptive plume from a safe distance of 1 km from the vents, thus considerably decreasing the risks involved in sampling. This highlighted a clear time decrease in SO2 concentrations and SO2/HCl ratios, which was interpreted as due to progressive exhaustion of volatile degassing and eruption energy.
    Description: Published
    Description: D21308
    Description: partially_open
    Keywords: volcanic plumes ; impact of volcanic emissions ; sulfur and halogens chemistry ; 04. Solid Earth::04.03. Geodesy::04.03.06. Measurements and monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
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  • 64
    Publication Date: 2017-04-04
    Description: From December 2002 to July 2003, Stromboli volcano was characterized by a new effusive stage of eruption after a period of extraordinary strombolian activity. Signals recorded in two continuous monitoring stations during the eruption, which have already been presented in very recent papers, evidenced anomalies in the CO2 flux just before the onset of the eruption. A more detailed analysis carried out on the data subset acquired during the eruption, integrated by daily field observations of the scientific personnel working at the volcanological observatory in Stromboli, showed that CO2 flux and soil temperature are strictly related to volcanic events. Furthermore, the relative minima and maxima of the two parameters showed a strong correlation with wind speed and direction. This fact was especially true at the summit station, whereas at the coastal sites seasonal and meteorological effects masked the volcanic signal. The analysis of the wind data, particularly the relationships between wind speed and direction, air and soil temperature, and local circulation of atmospheric air masses revealed that during the eruption, in the summit area of Stromboli air movements were not only related to atmospheric circulation but were also significantly affected, and in certain cases caused, by volcanic activity. This conclusion was reached by observing several anomalies, such as the discrepancies in the wind direction between the two stations, higher air temperatures at the summit site, and inversion of direction for wind before and after the reopening of the conduit in a major explosion on 5 April 2003. The relationships found between volcanic activity, soil temperatures, CO2 fluxes, and wind speed and direction indicate that soil temperature measurements, in an open conduit volcano such as in this case, could be used to monitor the level of volcanic activity, along with CO2 flux. Furthermore, the possible volcanic origin of a peculiar type of air circulation identified in the summit area of Stromboli suggests that the separation between volcanic and atmospheric signals might not be obvious, requiring monitoring over a wide area, rather than a single location.
    Description: Published
    Description: Q12001
    Description: partially_open
    Keywords: carbon dioxide flux ; continuous monitoring ; soil temperature ; wind ; 01. Atmosphere::01.01. Atmosphere::01.01.07. Volcanic effects ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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  • 65
    Publication Date: 2017-04-04
    Description: Marked increases of CO2, H2 and He dissolved in thermal waters and changes in the dissolved carbon isotopic composition, were observed at Stromboli before the 28 December 2002 eruption and before a violent explosive paroxysm occurred on 5 April 2003. High anomalous CO2 flux values were recorded at the crater rim since a week before the eruption onset. The first anomalies in the thermal waters (dissolved CO2 amount) appeared some months before the eruption, when magma column rose at a very high level in the conduit. High peaks of dissolved H2 and He were recorded a few days before the paroxysm. Carbon isotopic composition indicates a magmatic origin of the dissolved CO2 whose increase, together with those of H2 and He, is attributed to an increasing output of deep gases likely produced by depressurization of a rising batch of a deep gas-rich magma, whose fragments have been emitted during the explosion.
    Description: Italian Civil Protection
    Description: Published
    Description: L07620
    Description: partially_open
    Keywords: Stromboli ; geochemical precursors ; CO2 flux ; pH ; 03. Hydrosphere::03.04. Chemical and biological::03.04.03. Chemistry of waters ; 03. Hydrosphere::03.04. Chemical and biological::03.04.05. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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  • 66
    Publication Date: 2017-04-04
    Description: The performance of a newly-developed portable gas analyzer, capable of real-time measurement of CO2, SO2 and H2S concentrations in volcanic gases, was tested at La Fossa Crater, Vulcano Island. The gas analyzer was used to acquire about 3000 determinations over the fumarolic field, allowing the definition of its chemical structure and heterogeneity. Our high-resolution analysis reveals that, in December 2004, the La Fossa fumarolic field was characterized by an oxidized inner core (SO2/H2S ratios of 3), and by more reducing conditions on its northern edge (SO2/H2S ratios of 1; range: 0.2–3.3). CO2/(SO2+H2S) molar ratios averaged 35 ± 21, with overlapping compositions for rim and inner crater fumaroles. S-poor compositions (CO2/(SO2+H2S) 50) characterized the field margins, probably due to deposition of native sulfur. Based on the above data and an SO2 flux of 18 ± 3 t.d-1, we estimate CO2 and H2S output rates from the volcano of 420 ± 250 and 4 ± 2 t.d-1, respectively.
    Description: Published
    Description: L13309
    Description: partially_open
    Keywords: electrochemical sensors ; fumarolic gases ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
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  • 67
    Publication Date: 2017-04-04
    Description: Flank instability and collapse are observed at many volcanoes. Among these, Mt. Etna is characterized by the spreading of its eastern and southern flanks. The eastern spreading area is bordered to the north by the EW-trending Pernicana Fault System (PFS). During the 20022003 Etna eruption, ground fracturing along the PFS migrated eastward from the NE Rift, to as far as the 18 km distant coastline. The deformation consisted of dextral en-echelon segments, with sinistral and normal kinematics. Both of these components of displacement were one order of magnitude larger (~1 m) in the western, previously known, portion of the PFS with respect to the newly surveyed (~9 km long) eastern section (~0.1 m). This eastern section is located along a pre-existing, but previously unknown, fault, where displaced man-made structures give overall slip rates (11.9 cm/year), only slightly lower than those calculated for the western portion (1.42.3 cm/year). After an initial rapid motion during the first days of the 20022003 eruption, movement of the western portion of the PFS decreased dramatically, while parts of the eastern portion continued to move. These data suggest a model of spreading of the eastern flank of Etna along the PFS, characterized by eruptions along the NE Rift, instantaneous, short-lived, meter-scale displacements along the western PFS and more long-lived centimeter-scale displacements along the eastern PFS. The surface deformation then migrated southwards, reactivating, one after the other, the NNWSSE-trending Timpe and Trecastagni faults, with displacements of ~0.1 and ~0.04 m, respectively. These structures, along with the PFS, mark the boundaries of two adjacent blocks, moving at different times and rates. The new extent of the PFS and previous activity over its full length indicate that the sliding eastern flank extends well below the Ionian Sea. The clustering of seismic activity above 4 km b.s.l. during the eruption suggests a deep décollement for the moving mass. The collected data thus suggests a significant movement (volume 〉1,100 km3) of the eastern flank of Etna, both on-shore and off-shore.
    Description: Published
    Description: 417-430
    Description: partially_open
    Keywords: Volcano spreading ; Fracturing ; Mt. Etna ; Pernicana Fault System ; NE Rift ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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  • 68
    Publication Date: 2017-04-04
    Description: A major explosion occurred at Stromboli on April 5 2003, being the most powerful event over a period of exceptional eruptive activity lasting from December to July. Here, we describe results from a network of diffusive tubes set up on the Stromboli’s summit area, aimed at a characterisation of plume composition (SO2, HCl, HF) prior to and after April 5. Data analysis revealed anomalous sulphur degassing 2–3 days before the event, when SO2/HCl ratios (9) significantly higher than those typical of quiescent degassing (1) were recorded. We interpret this exceptional plume signature as an evidence of S-rich magmas ascending in the shallow plumbing system, and propose high SO2/HCl as a potential precursor of major explosions on the volcano. The post-April 5 phase was characterised by time-decreasing SO2/HCl and SO2/HF plume ratios, ascribed to declining magma feeding as a prelude to restoration of ‘‘normal’’ Strombolian activity.
    Description: Published
    Description: L14607
    Description: partially_open
    Keywords: magmatic degassing ; paroxysm ; Stromboli ; 04. Solid Earth::04.03. Geodesy::04.03.06. Measurements and monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
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  • 69
    Publication Date: 2017-04-04
    Description: On 2nd/3rd November 2002, a huge amount of gas, mainly composed of CO2, was suddenly released from the sea bottom off the coast of Panarea, producing a ‘‘crater’’20 by 10 meters wide and 7 meters deep. The gas output was estimated to be 109 l/d, two orders of magnitude higher than that measured in the 1980s. The anomalous degassing rate lasted for some weeks, slowly decreasing to an almost constant rate of about 4 x 107 l/d after two months. The geothermo- barometric estimations revealed an increase of both the temperature and pressure in the geothermal system feeding the sampled vents. The 3He/4He ratios were similar to those measured in nearby Stromboli. We have monitored the area for the last two decades, and based on our intensive and extensive geochemical measurements, have ascertained that the geothermal reservoir has lost its steady state. We maintain that a new magmatic input caused these phenomena.
    Description: - Istituto Nazionale di Geofisica e Vulcanologia, Osservatorio Vesuviano, Naples, Italy. - Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Palermo, Palermo, Italy. - Dipartimento Chimica e Fisica della Terra ed Applicazioni, Palermo, Italy.
    Description: Published
    Description: L07619
    Description: partially_open
    Keywords: Submarine degassing ; magmatic fluids ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.04. Thermodynamics ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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  • 70
    Publication Date: 2017-04-04
    Description: Five gas discharges in the area of Mount Etna volcano (Italy) and in the near Hyblean plateau have been monitored since 1996. All the emissions displayed low contributions from crustal fluids, whereas magmatic gases were the main component. Selective dissolution of these gases into hydrothermal aquifers has been recognized and modeled, allowing us to calculate the original composition of the magma-released gases. The inferred composition of the magmatic gases exhibits synchronous variations of He/Ne and He/CO2 ratios, which are coherent with the magma degassing process. On the basis of numerical simulations of volatile degassing from Etnean basalts we have computed the initial and final pressures of the magma batches feeding the emissions. We thus can define the levels of the Etna plumbing system where magmas are stored. Pressure values were around 360 and 160 MPa for initial and final stages, respectively, meaning related depths of about 10 and 3 km below sea level, matching those obtained by geophysical investigations for the deep and shallow magma reservoirs. In addition, we have been able to recognize episodes of magma migration from the deeper reservoir toward the shallow one. An important magma injection into the shallow storage volume was detected during the onset of the 2001 eruption (17 July). No further injection had taken place during this period until September 2001, providing a possible reason for the quick exhaustion of the eruption. In view of this we suggest that the sampled emissions are a powerful geochemical tool to investigate the Etna’s plumbing system and its magma dynamics, as well as the development of eruptive events.
    Description: Published
    Description: 2463
    Description: partially_open
    Keywords: gas geochemistry ; magma degassing ; modeling ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.04. Thermodynamics ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 71
    Publication Date: 2017-04-04
    Description: Five years of gas monitoring from selected sites suggest that Mt Etna’s plumbing system is much more extensive than previously reported. It extends at least 40 km SW from the volcano’s boundary along the NE-SW regional fault, where it discharges about 200 tons/day of gas, containing helium with mantle-type isotopic composition. Synchronous variations of 3He/4He isotopic ratios in gas sampled at sites located 60 kilometers apart have allowed us to detect pulses of ascending magma in the plumbing system, thus providing a powerful tool for eruption forecasting. Following summer 2001 eruption, the still increasing trend of the 3He/4He ratios indicates that magma storage is even now occurring at a shallow depth. Hence, the volcano maintains a high capacity to re-erupt within the next few months.
    Description: Published
    Description: 1057
    Description: partially_open
    Keywords: helium isotopes ; geochemical monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 72
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    Cell & tissue research 151 (1974), S. 369-384 
    ISSN: 1432-0878
    Keywords: Giant dopamine neurone ; Planorbis corneus ; Localization of dopamine ; Axon tracing ; Light and electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary There is a giant dopamine-containing cell (GDC) in the left pedal ganglion of Planorbis corneus. Some presynaptic endings of the GDC are located within the visceral and left parietal ganglia, other endings are located peripherally. Dense-cored vesicles of 50–250 nm diameter were observed in the perikaryon and primary axon of the GDC. Electron microscope histochemistry suggests that these vesicles contain dopamine. Vesicles with a similar appearance are present in some axonal processes located in areas of the nervous system known to contain presynaptic endings of the GDC. This neurone offers unique advantages for studying the role of neuronal dopamine.
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  • 73
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    Cell & tissue research 151 (1974), S. 489-498 
    ISSN: 1432-0878
    Keywords: Limbic system ; Cat ; Amygdaloid body ; Light and electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The present study was undertaken to re-examine the central nucleus of the cat in Nissl stained sections, to describe its fine structural characteristics, and to compare the lateral subdivision of this nucleus with the putamen. In Nissl preparations, it was observed that the lateral subdivision of the central nucleus contains a fairly homogeneous population of small cells while the putamen contains both small and large cells. It is the presence of a few large cells at the lateral periphery of the lateral part of the central nucleus that makes the boundary between the two nuclei indistinct. Examination of the fine structure of the medial and lateral subdivisions of the central nucleus revealed the presence of many boutons containing flattened vesicles and fewer with spheroid vesicles. In contrast, most of the boutons in the putamen have spheroid vesicles. It is concluded that the lateral subdivision of the central nucleus may be distinguished from the putamen, except at its most lateral border, by its homogeneous population of small cells and its many boutons containing flattened vesicles.
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  • 74
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    Cell & tissue research 153 (1974), S. 219-226 
    ISSN: 1432-0878
    Keywords: Cerebellar cortex ; Man and other mammals ; Golgi cells ; Regional differences ; Light and electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The number of Golgi cells per unit volume was determined in different regions of the cerebellar cortex of man and of ten other mammals. Despite the general belief in the uniform architecture of the cerebellar cortex, regional differences in the distribution of Golgi cells were found. In the inferior parts of the vermis, the number of Golgi cells per unit volume is twice that in the corresponding hemispheres. In addition, there are differences between the anterior and inferior parts of the vermis. These differences are a feature of the cytoarchitecture of the cerebellum in man and all the investigated mammals. The ratio of Purkinje cells to Golgi cells was also determined and found to differ in different species. In man, this ratio is 1∶1.5, while in the monkey and cat it is almost 1∶1.9 and in the rat 1∶3.3. These differences in the ratio of Purkinje cells to Golgi cells are discussed from the point of view of cerebellar evolution.
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  • 75
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    Cell & tissue research 153 (1974), S. 383-398 
    ISSN: 1432-0878
    Keywords: Aesthete Organs ; Lepidochitona cinereus ; Cell types ; Secretory cells ; Light and electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The structure of the aesthete organs of the chiton Lepidochitona cinereus (L.) is described by light and electron microscopy. The observations do not discount a sensory function for these organs, but possible sensory structures such as microvilli and cilia are poorly organised. Most of the aesthete is taken up with large cells actively forming secretory products and apparently passing them proximally in the aesthete canal towards the animal. Comparisons are drawn with the brachiopod caecae.
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  • 76
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    Cell & tissue research 153 (1974), S. 399-413 
    ISSN: 1432-0878
    Keywords: Spinal ganglia (Rat) ; Cell division ; Autoradiography ; Neurone morphogenesis ; Light and electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Pulse labelling with tritiated thymidine was used to determine the time of the final division of the neuroblasts which subsequently form rat lumbar dorsal root ganglion neurones. The final division occurred during a 4 day period, the maximum frequency being on day 12 of gestation. Separation of the ganglion cells into large light neurones and small dark neurones showed that the large light neurones were formed earlier than the small dark neurones. In both cases the final divisions occurred over a period of 3–4 days, but the peak rate of formation of large neurones was on day 12, and that of the small neurones was on day 13. Low power electron micrographs were used to measure mean cell diameter throughout development from day 11 of gestation until a postnatal age of 225 days. A marked increase in cell diameter occurred on day 15–15.5, about 3 days after the final cell divisions of the majority of the cells. The rate of growth increased just before birth, but no increase in mean cell diameter was found between day 21 of gestation and the third day postnatal. The growth was again rapid after this period until a plateau in cell diameter was reached about 33 days after birth.
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  • 77
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    Cell & tissue research 155 (1974), S. 291-320 
    ISSN: 1432-0878
    Keywords: Adenohypophysis ; Chicken ; Developmental endocrinology ; Epithelial differentiation ; Light and electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Anlagen of the pars distalis (Rathke's pouch), adjacent ectoderm, endoderm, infundibulum and mesenchyme left in situ were put in 3% glutaraldehyde between 1–3 pm and fixed overnight. Epon sections of this material from six White Leghorn, Gallus gallus, embryos fixed at each stage, and of two control partes distales from laying hens of the same flock were examined. At stage 17 (∼12 hours after formation) Rathke's pouch cells were stratified, uninnervated, non-vascularized and stellate, with high nucleo-cytoplasmic ratios and few organelles. Except for lipid inclusions, pouch cells did not appear appreciably different by stage 27, either regionally within the pouch wall or from the adjacent epithelioid cells. Apparent major changes indicative of cytoplasmic maturation by stage 27 included: reduction in number of polysomes; appearance of single-membraned, dumb-bell shaped to rounded, dense granula which were usually in basal position but also in areas of the Golgi apparatus; greater prominence of rough endoplasmic reticulum with cisternae containing dense material, and of the Golgi apparatus, notably with variously dense and/or coated vesicles and material; reduction in lipid inclusions by stage 24. Non-terminating axons in the infundibulum were first seen at stage 27. We found no convincing evidence for any possible morphogenetic or other relationship between the pars distalis and surrounding tissues. “Melanophore-stimulating hormone-activity”, reported to appear on day 5 of incubation, “stored thyroid-stimulating hormone” or pars distalis hormone granula or activities could not be identified. Rathke's pouch and other epithelioid structures may have been secreting, taking up nutrients and/or differentiating, activities which could be important for yolk sac development, nutrition and/or cytodifferentiation, respectively.
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  • 78
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    Cell & tissue research 151 (1974), S. 509-523 
    ISSN: 1432-0878
    Keywords: Gill ; Trout ; Secondary lamellae ; Development ; Light and electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A light and electron microscope study of secondary lamellae of trout developing at 10° C is described. Collagen is secreted by mesenchyme cells in the connective tissue of the developing gill filament. This becomes enclosed in infoldings around the peripheries of mesenchyme cells. These cells become aligned in a single plane within folds of basement membrane and epithelium. The basement membrane of opposite sides of the fold becomes connected by a thick layer of collagen. Blood spaces form around the margin of the fold, connecting afferent and efferent filament blood vessels. Endothelial granules form in cells lining the outer border of the marginal channel when blood flow begins. Rows of pillar cells separate from the proximal layer of mesenchyme cells as the secondary lamellae develops further. New secondary lamellae are added at the filament tips. At 28 days, the basement membrane consists of 2 layers, a fine fibrous layer and 5–15 orthogonally arranged layers of collagen fibres. By 31 days, the collagen is arranged at random and the layer is thinner. A clear layer is also present by 67 days. A multilayered epithelium containing mucous and chloride cells is present at 28 days. By 102 days, the secondary lamellae are covered by 2 layers of epithelial cells only. Chloride cells are present in much greater numbers in developing gills than in the adult.
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  • 79
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    Cell & tissue research 155 (1974), S. 449-453 
    ISSN: 1432-0878
    Keywords: Coronet cells ; Teleostei ; Neurohypophysis ; Hypersalinity ; Light and electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In several adult specimens of Mugil capito caught in a hypersaline lagoon, an intra-neurohypophyseal channel system lined with coronet cells has been observed. Coronet cells are normally found only in the saccus vasculosus, and in modern Teleostei, this structure is always completely separated from the neurohypophysis. The penetration of coronet cells into the neural lobe, may be an adaptive phenomenon possibly connected with an osmo-protective role of these cells.
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  • 80
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    Cell & tissue research 148 (1974), S. 331-345 
    ISSN: 1432-0878
    Keywords: Microtubules ; Movement ; Selenidium ; Pellicle ; Light and electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The archigregarine, Selenidium, is parasitic in the digestive tracts of some polychaete worms. The trophozoites of Selenidium are worm-like in appearance, and are attached by one end to the intestinal epithelium of the host, while the remainder of the organism performs rhythmic bending movements, reminiscent of nematode worms. The trophozoites have a multilayered, longitudinally folded pellicle, and beneath this are longitudinally oriented microtubules, arranged in precise fashions. The arrangements of both the pellicle, and the microtubules change during the bending movements. Furthermore, if trophozoites are treated with the drug colchicine, the sub-pellicular microtubules are destroyed, the patterns of pellicular folding are altered, and the trophozoites cease to move. The contribution of the pellicle and the microtubules to the characteristic movements of the trophozoites is evaluated and discussed.
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  • 81
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    Cell & tissue research 149 (1974), S. 81-89 
    ISSN: 1432-0878
    Keywords: Muscle cells ; Tardigrada ; Light and electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The somatic muscles of the tardigrades Macrobiotus hufelandi and Milnesium tardigradum consist of elongated cells which are structurally independent of each other and insert in the body wall. The contractile part of the muscle cells contains thick and thin myofilaments. The thin filaments run together in typical dense bodies. In relaxed muscles clear A-, I- and H-zones are formed, and the dense bodies are often accumulated in groups. In ribbon like I-zones they are sometimes arranged side by side in rows and resemble fragmented Z-rods. The sarcoplasmic reticulum is localized primarily in the small region between the contractile apparatus and sarcolemma, and is represented by a system of smooth, flat, reticulated cisternae. The contractile apparatus of the somatic muscles is compared to that of smooth and obliquely striated muscles of several invertebrates. On the basis of certain distinguishing features of the contractile part of somatic muscles of tardigrades, it is suggested that these muscles should be referred to as a type intermediate between smooth and obliquely striated muscles.
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  • 82
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    Cell & tissue research 149 (1974), S. 473-479 
    ISSN: 1432-0878
    Keywords: Aquatic eggs ; Insects ; Envelopes ; Respiration ; Light and electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The aquatic egg of Nymphula has no trabecular layer and no aeropyles. Four tubular micropyles only traverse the anterior part of the chorion. Presumably, the egg contains a sufficient quantity of air to allow the development of the caterpillar when the egg is immersed in paraffin oil. Under the chorion, the vitelline membrane possesses crypts and furrows which seem filled by air. This air can enter through the permeable regions of the vitelline membrane. The mucus, between the chorion and the under surface of the leaf, may constitute an external air reserve dependent on photosynthesis.
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  • 83
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    Cell & tissue research 150 (1974), S. 57-66 
    ISSN: 1432-0878
    Keywords: Purkinje Fibres ; Avian heart ; Innervation ; Light and electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The innervation of the Purkinje fibres in the atrium of the heart of the adult fowl was investigated by light microscopy, using the Champy-Maillet OsO4-ZnI2 technique and the cholinesterase reaction and by electron microscopy. After impregnation of the tissue with OsO4-ZnI2, the dark-stained nerve fibres were clearly visible on the unstained Purkinje fibres. In the upper part of the posterior wall of the right atrium, the diffuse portion of the conducting system is especially richly innervated by varicose and smooth nerve fibres. Some of these fibres are cholinesterase-positive. The terminal axons run in the space between the Purkinje fibres and the fibrocytic envelope. They are either naked or accompanied by Schwann cell processes. In addition to varicosities containing granular vesicles, there are varicosities containing agranular vesicles with oval profiles. In the “en passant” synapses, the width of the synaptic cleft between a varicosity and the Purkinje cell is about 600 Å. The innervation of the Purkinje fibres appears more like the innervation of smooth muscle than that of striated skeletal muscle. The possible role of Purkinje fibres as mechanical receptors is discussed.
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  • 84
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    Cell & tissue research 151 (1974), S. 499-508 
    ISSN: 1432-0878
    Keywords: Limbic system ; Cat ; Amygdaloid body ; Hypothalamus ; Stereotaxic lesions ; Light and electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In order to determine the origin of the hypothalamo-amygdaloid connections in the cat, small lesions were placed at various rostro-caudal levels of the hypothalamus. The animals were sacrificed after a period of 4, 8 or 11 days and the brains stained with the Nauta (1957), Fink and Heimer (1967) or Wiitanen (1969) method for the demonstration of degenerating axons and their terminals. It was observed that the anterior hypothalamic nucleus sends a small projection to the medial subdivision of the central nucleus and to the basal and lateral nuclei of the amygdala. The lateral preoptic area sends a larger projection to the anterior amygdaloid area, both subdivisions of the central and basal nuclei, and to the lateral and medial nuclei. No degeneration was observed in the amygdala following lesions in the medial preoptic area, the ventromedial nucleus or the lateral hypothalamic area caudal to the anterior hypothalamic area. In a series of animals with lateral preoptic lesions, the site of termination of degenerating boutons on neurons of the amygdaloid nuclei was determined and the course of the degenerative process followed over a period ranging from 2 to 15 days. Many of the boutons, especially in the earlier stages of degeneration, appeared to be of the B3 type, containing flattened vesicles and forming symmetrical synaptic contacts with dendrites or somata. With longer post-operative survival times, however, they became increasingly electron dense and shrunken, so that the bouton type could not be determined.
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  • 85
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    Cell & tissue research 153 (1974), S. 365-381 
    ISSN: 1432-0878
    Keywords: Gills ; Lepidosiren paradoxa ; Epithelia ; Transport adaptions ; Light and electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The gills of Lepidosiren are very much reduced, consisting of a few lobe-like filaments. The gill epithelium differs from most other fish in being 4–7 layers thick. Three varieties of cell are described which occur in the inner epithelial layers. It is suggested that these represent stages in the synthesis of a granular secretory product. The superficial cells show characteristics of all 3 cell varieties, the granules apparently being voided into the microvillar pits at the surface. Surface cells are joined by junctional complexes typical of fish epithelia. Epithelial cells are separated by interstitial channels which are bridged by long cytoplasmic processes united by prominent desmosomes. Elongate mucous cells occur in large numbers. The Golgi apparatus is exceptionally large and well defined. It is characterised by accumulation of secretory products at numerous points along the cisternae. Wandering cells containing large granules and 2 types of leucocytes are also present in the interstitial channels. It is suggested that the gill epithelium is involved in active transport; pinocytotic vesicles are present on both sides of the inner epithelial cell layer and the blind interstitial channels are characteristic of transporting epithelia in which steady osmotic gradients operate.
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  • 86
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    Cell & tissue research 154 (1974), S. 135-150 
    ISSN: 1432-0878
    Keywords: Parotid glands (Rat) ; Secretion ; Sympathetic ; Autonomic innervation ; Cervical sympathectomy ; Light and electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Rats starved for 40 hours showed similar appearances in both parotid glands despite the fact that cervical sympathectomy had been performed on one side 24 hours before the tissues were removed. The acini of both glands of each animal were loaded with secretory granules and amylase estimations on both sides were similar. Rats starved for 40 hours and then fed chow for 1 1/2–2 1/2 hours showed variable depletion of secretory granules from their parotid acinar cells and corresponding alterations of amylase concentration. There was marked asynchrony in both granule depletion and the phase of resynthesis of individual cells. Rats starved during 40 hours and having had unilateral cervical sympathectomy 24 hours prior to a terminal eating phase of 1 1/2–2 1/2 hours showed big differences between the parotid glands on the different sides of each animal. The sympathectomised gland showed little or no depletion of secretory granules whereas the normally innervated gland showed a variable loss of granules, which was always greater than on the denervated side. Amylase estimations were also lower on the normally innervated side. It is concluded that normal reflex secretion of acinar granules in parotid glands of rats on eating requires intact sympathetic nerve pathways.
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  • 87
    ISSN: 1432-0878
    Keywords: Skin ; Anurans ; Regional differences in grafts ; Neuroepithelial relationships ; Light and electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Recent investigations have suggested specific differences in back and belly skin in anurans which appear to influence the quality of reflex responses obtained from various areas of the animals body. The present investigation represents a comparative morphological study of back and belly skin in control and skin-graftedRana pipiens, with special regard to the neuroepithelial relationships. A distinct difference in pigmentation of back and belly skin was observed. Intra-epithelial Merkel cells were present in all skin samples studied. The origins of the numerous unclassifiable cells in the Merkel cell region are discussed in relation to a presumed coordinating function of the Merkel cell during epithelial differentiation. Epitheliomesenchymal interactions were observed in the richly innvervated dermal regions. Two types of morphologically different intra-epithelial nerve endings were observed. These observations are discussed in relation to earlier observations on vertebrate skin and in relation to misdirected reflex responses obtained in skin-grafted anurans.
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  • 88
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    Keywords: Pigment cells ; Pterinosomes ; Skin ; Rana japonica ; Light and electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Structural changes in drosopterinosomes (red pigment granules) of Rana japonica in the process of erythrophore differentiation were studied by light and electron microscopy. On the basis of the degree of pterinosome differentiation, three types can be recognized: Typ-I drosopterinosomes appear first during metamorphosis and have clear limiting membranes and amorphous materials within. Those of type-II are found in abundance shortly after metamorphosis and have inner structures, consisting of fibrillae and/or small lamellae in dense concentric arrangement. Type-III is found abundantly in adults and acquires an almost homogeneously electron-dense mature morphology, probably from the deposition of electron-dense materials. On the basis of counts of pterinosomes, a successive transformation from type I to III is suggested. The differences among red drosopterinosomes, yellow sepiapterinosomes in xanthophore and melanosomes are not always distinguishable electron microscopically. Discrimination is possible by careful examination of lamellar patterns characteristic of the respective granules and by a simultaneous application of light and electron microscopy. From this viewpoint, a re-evaluation of the identification of granules previously reported was effected.
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  • 89
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    Cell & tissue research 142 (1973), S. 1-12 
    ISSN: 1432-0878
    Keywords: Harderian gland ; Hamster ; Sexual dimorphism ; Alveolar cells ; Light and electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The lobules of the Harderian glands of young male and female hamsters are widely separated by connective tissue and are made up of alveolar cells containing small vacuoles. There is considerable increase in the size of the lobules by 12 days. Based on size distribution of vacuoles two types of alveolar cells can be recognized in the male hamsters 4 weeks and older. The Harderian glands of 2-week animals of both sexes contain a black-brown pigment. The appearance of pigment is accompanied by a proliferation of membranes. In the female the amount of pigment increases with increasing age until 4 weeks of age and then remains at a relatively stable level. In the male no pigment was found after 4 weeks of age. Membrane-bounded juxtanuclear structures are present in the alveolar cells of both sexes until 3 weeks of age. These structures appear to play different roles in the male and female hamsters. The differentiation of the alveolar cells into light and dark types must take place during the 3rd week of postnatal development. A possible relationship between the levels of gonadal hormones and the occurrence of pigment at different ages in both sexes is also discussed.
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  • 90
    ISSN: 1432-0878
    Keywords: Crustacean CNS ; Olfactory and accessory lobes ; Glomerular neuropile ; Light and electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The olfactory and accessory lobes of the crayfish, Cherax destructor contain glomeruli. Light microscope and electron microscope studies show that these glomeruli are the only regions of synaptic activity in the lobes and that at least four separate sets of axons meet within the glomeruli. The olfactory glomeruli are column shaped, complex structures with no large single pre- or postsynaptic elements. The accessory lobe glomeruli follow a more conventional pattern and each has one large axon ending in a terminal arborization where it makes synaptic contact with large numbers of smaller fibres. The large fibre is presynaptic.
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  • 91
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    Cell & tissue research 147 (1973), S. 127-148 
    ISSN: 1432-0878
    Keywords: Melanophores (Teleost) ; Pigment migration, microtubules ; Colchicine, vinblastine ; Light and electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The antimitotic drugs colchicine and vinblastine were applied to the melanophores of isolated scales of Pterophyllum scalare. The time course of inhibition of pigment migrations was studied quantitatively with the photoelectric method. Within one hour of treatment with 5 mM colchicine, a partial and reversible inhibition of pigment movements is obtained. During this time, the number of microtubules per cell process does not differ significantly from controls when pigment is dispersed. However, their number increases concomitantly with the decrease in rate of aggregation induced by KCl up to about the same value as in dispersed pigment cells. This indicates a close connection between pigment movements and the microtubule turnover known to occur in angelfish melanophores. When applied in a concentration of 0,2 mM, vinblastine has a total and irreversible effect on pigment movements, with an especially rapid and profound inhibition of pigment dispersion. The fine structure of vinblastine-treated melanophores is characterized by an almost complete loss of microtubules and the appearance of crystalloid bodies, which differ in fine structure from vinblastine-induced crystals of all other cell types so far examined. Possibly their peculiar structure is related to special properties of melanophore microtubules, such as rapid turnover and relatively high resistance to colchicine.
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  • 92
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    Cell & tissue research 144 (1973), S. 489-509 
    ISSN: 1432-0878
    Keywords: Gills ; Scyliorhinus canicula ; Circulation sphincters ; Hydrostatic skeleton ; Light and electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The anatomy of the blood supply to the gills of the dogfish, Scyliorhinus canicula, is described. The anatomical basis for a counter-current exchange system at the respiratory surfaces is reported. Within the interbranchial septum there is a capillary network joining all the afferent branchial arterioles of the gill. The structure of the walls of the corpus cavernosum is found to be of smooth muscle cells supported by a basal lamina and connective tissue and lined by endothelial cells containing phagocytic vesicles. Both the capillary network and corpus cavernosum are suggested to function in smoothing the pressure pulses of the blood flow. Pre- and post-lamellar vessels and pre- and post-lamellar sphincters are described. The sphincters are thought to control the number of secondary lamellae physiologically in the respiratory circuit, and by retaining blood within nonperfused lamellae to act in conjunction with pillar cells (contracting in antagonism to the hydrostatic skeleton of the blood) to maintain the rigidity of secondary lamellae in the water current. Whorls of cells of unknown function are found within the interbranchial septum. In the epithelium lining the water channel large cells having a complexly branching plasma membrane and a very large central vacuole occurs. The cytoplasm lining the lumen contains numerous vacuoles each surrounded by a double membrane.
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    Cell & tissue research 139 (1973), S. 1-27 
    ISSN: 1432-0878
    Keywords: Glandulomuscular cells ; Hydra ; Basal disk ; Light and electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The glandulomuscular cells of Hydra are located exclusively in the basal disk. They are derived from epithelio-muscular cells which have been forced proximally. Light and electron microscopical studies show that prior to their destruction and elimination, the transformed epithelio-muscular cells (i.e. the glandulomuscular cells) undergo certain striking morphological and physiological changes. Golgi complexes and elements of rough E. R. increase remarkably in activity, and individually or jointly produce at least six types of morphologically different droplets. One additional type of droplet is thought to originate from neighboring digestive cells. Although the chemical nature of the individual droplets is uncertain, it is known that some are Alcian blue and PAS positive and contain hyaluronic acid. These evidences suggest the presence of an acid mucopolysaccharide material, the adhesive agent which attaches the animal to a substrate. The myonemes contain thick (200 Å in diameter) and thin (60 Å in diameter) filaments as in epithelio-muscular cells. There are also filaments of intermediate sizes and large fibers (770 Å in diameter). The myonemes are oriented radially with respect to the aboral pore and therefore in addition to contributing to the contraction and relaxation of the body column, they apparently regulate the opening and closing of the aboral pore. Although there is no evidence to substantiate the mechanism for transformation of epithelio-muscular cells to glandulomuscular cells as well as cell death of the latter cell types, these problems are discussed briefly.
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    Cell & tissue research 139 (1973), S. 29-45 
    ISSN: 1432-0878
    Keywords: Nerve cells ; Hydra ; Basal disk ; Epithelial cells ; Light and electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In addition to glandulomuscular cells, three other cell types are found in the basal disk of Hydra. These are interstitial cells, cnidoblasts and nerve cells. Although only a few of the two former cell types are recognized in this region, the observations from this study refute previous statements to the contrary. Nerve cells are concentrated in the basal disk where they form a type of “network” system, due to the presence of bipolar, tripolar and multipolar cells. In some specimens, they assume a circular arrangement around the base of the polyp. Using morphological criteria for identifying the three types of epidermal nerve cells (neurosensory, neurosecretory and ganglionic) in other body regions, only neurosensory and neurosecretory cells are observed in the basal disk. These are indistinguishable ultrastructurally from their respective counterparts in other regions. It is possible that ganglionic cells are also present in the basal disk, but there may be few such cells. It is suggested that the three cell types originate from the budding region and these precursor cells are then forced proximally. Interstitial cells, escaping their differentiative function, do not develop apparently into other cell types of the basal disk. Cnidoblasts contain normal nematocysts but their functional ability is uncertain. Neurosensory and neurosecretory cells arise directly and independently from interstitial cells in the budding region, as evidenced by the appearance of immature nerve cells in the peduncle and their absence in the basal disk. Although viable cells may be discarded from the basal disk, it is believed that most cells die in situ and are then eliminated. The possible role of nerve cells is discussed briefly.
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  • 95
    ISSN: 1432-0878
    Keywords: Caecal epithelium ; Trematodes, Cercariae ; Extracellular membranes, Membranous whorls ; Light and electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The intestinal caeca of the intraredial cercaria of Neophasis lageniformis differ in several aspects from previous descriptions of the intestinal caeca of other digenetic trematodes. The caeca are lined with a single-layered, non-syncytial epithelium with lamellate projections into the lumen. The cells are rich in glycogen particles and contain abundant granular endoplasmic reticulum. The apical cell membrane, which displays a unit membrane structure, is always covered by an external membrane of the same thickness as a unit membrane but showing no double-layered substructure. The external membrane, which is not equivalent to a glycocalyx, may continue from one cell to another. Apically on the projections the external membranes are apparently pushed out forming large, extracellular whorls, which fill up the caecal lumen. In the lumen there are also found crystal-like structures and lipid-like bodies which are suspended in a granular substance. The possible origin and function of the extracellular bodies are discussed.
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  • 96
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    Cell & tissue research 138 (1973), S. 113-132 
    ISSN: 1432-0878
    Keywords: Eggs ; Insects (Triatoma infestans) ; Embryogenesis ; Envelopes, Permeability ; Light and electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The thick rigid chorion of the egg of Triatoma secreted by the follicle cells shows two porous layers: an aerial layer in the exochorion, an alveolar one in the endochorion. The anterior part of the eggshell is closed up by an operculum which is heaved up by the hatching larva. The operculum has no alveolar layer. The air enters through the numerous holes of the shell surface into the aerial layer and through the micropyles into the alveolar layer. The egg has no respiratory plastron. The follicle cells produce also a vitelline envelope whose structure shows a rapid condensation at fertilization time. During its development the embryo secretes two layers: serosal and embryonic cuticle. At high humidities, at low temperatures the egg is able to increase its weight during the early stages of embryogenesis, and this increase stops when the serosal cuticle is secreted. In a dry atmosphere the egg loses water but can develop if the temperature is higher than 20°C. The little permeability of the egg is related to the structure of its envelopes. The chorion and the vitelline envelope prevent the water from getting out of the egg. The serosal cuticle seems to be opposed to the penetration of the water into the egg. The role of the embryonic cuticle is probably limited in the transit of water.
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  • 97
    ISSN: 1432-0878
    Keywords: Iris ; Muscle, Nerves ; Light and electron microscopy ; Acetylcholinesterase ; 6-Hydroxydopamine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The adrenergic and cholinergic innervation to the rat iris has been studied at a light and electron microscopic level. Catecholamine fluorescence histochemistry showed adrenergic nerves to be present in both the dilatator and the constrictor pupillae regions. At a fine structural level the terminal innervation of the iris was studied and criteria for the differentiation between presumptive adrenergic and presumptive cholinergic axon terminals were examined. To aid this examination presumptive adrenergic axons were either labelled with the “false” adrenergic transmitter, 5-hydroxydopamine, or chemical sympathectomy performed using 6-hydroxydopamine. The value of using acetylcholinesterase staining as a marker for cholinergic nerve terminals was also studied. Results showed a mixed adrenergic/cholinergic innervation to the dilatator pupillae. In the constrictor pupillae an exclusively cholinergic innervation was found although adrenergic and cholinergic nerves were found supplying the blood vessels and at the dilatator-constrictor interface. These findings are discussed with regard to innervation-function relationships in the iris.
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  • 98
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    Cell & tissue research 138 (1973), S. 315-326 
    ISSN: 1432-0878
    Keywords: Olfactory mucosa ; Frog ; Innervation ; Ultrastructure ; Light and electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The olfactory mucosa of frog has been studied at an ultrastructural level to confirm previous light microscope observations in regard to the presence, in the sensory epithelium, of nerve fibres not belonging to the first cranial nerve proper. It has been observed that both myelinated and unmyelinated nerve fibres are present in the lamina propria and that eventually these fibres terminate inside the epithelium. Unmyelinated fibres usually contain dark core vesicles and similar content is seen in their intraepithelium terminals. Terminals containing only clear vesicles are also observed in the epithelium and they are believed to represent the terminals of the myelinated fibres. The significance of these ultrastructural findings is discussed in view of their functional meaning.
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  • 99
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    Cell & tissue research 141 (1973), S. 203-221 
    ISSN: 1432-0878
    Keywords: Median eminence ; Newt ; Zones ; Light and electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In the median eminence of the newt a medial region and two lateral regions are described. In cross section, the medial region appears to be made up of 1) an outer or glandular zone (Zone I) containing aldehyde-thionine-positive and negative nerve fibres and blood capillaries. Nerve fibres appear aligned in palisade array along the capillaries. 2) An inner zone (Zone II) made up of a) a layer of aldehyde-thionine-positive nerve fibres (fibrous layer) belonging to the preoptic hypophyseal tract and b) a layer of ependymal cells lining the infundibular lumen and reaching the blood vessels with their long processes. The lateral regions display a less pronounced stratification and aldehyde-thionine positive nerve fibres are nearly absent. A slender lamina (ependymal border) containing mainly aldehyde-thionine-positive nerve fibres and ependymal cells connects the median eminence to the pars nervosa. At the ultrastructural level, in the outer zone of the medial region at least 4 types of nerve fibres and nerve endings are identified: Type I nerve fibres containing granular vesicles of 700–1000 Å and clear vesicles (250–400 Å). Type II nerve fibres containing granular vesicles and polymorphous granules of 900–1300 Å and clear vesicles (250–400 Å). Type III nerve fibres containing dense granules of 1200–2000 Å and clear vesicles of 250–400 Å. Type IV nerve fibres containing only clear vesicles of 250–400 Å. In the inner zone too, all these nerve fiber types are found among ependymal cells, while the fibrous layer consists of nerve fibres containing granules of 1200–2000 Å in diameter. In the lateral regions Type I, Type II and Type IV nerve fibres and their respective perivascular terminals are found; axons containing dense granules (1200–2000 Å) are scanty. In these regions typical synapses between Type I nerve fibres and processes rich in microtubules are visible. The classification and functional significance of nerve fibres in the median eminence are still unsolved, but it may be assumed that nerve fibres of the medial region belong to both the preoptic hypophyseal and tubero hypophyseal tract, while the lateral regions are characterized by nerve fibres of the tubero hypophyseal tract. Peculiar specializations of the ependymal cells in the median eminence of the newt are also discussed.
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    Cell & tissue research 146 (1973), S. 45-67 
    ISSN: 1432-0878
    Keywords: Cerebellum (rat) ; Growth in Tissue culture ; Cell types ; Light and electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The outgrowth of newborn rat cerebellum cultivated in the Maximow assembly was studied from the time of explanation until the end of the 1st week “in vitro”. Dynamic characteristics of migrating cells were investigated with time lapse microcinematography and with phase and interference contrast. Three types of cells were identified: bipolar fusiform cells, fibroblasts and macrophages. The ultrastructure of these cells as seen with scanning and transmission electron microscopes is described. Bipolar cells display the same characteristics as those of migrating granule cells “in vivo”. Differentiation of these cells towards neuronal types becomes evident at the end of the first week “in vitro”. Axonal as well as dendritic growth cones were examined, and their ultrastructural characteristics described. Attention is focussed into the abundance of smooth endoplasmic reticulum, which in supposed active growth has the form of thin cisternae, and, at rest or in retraction takes the form of large vesicles. In the latter case, filopodia disappear, and the tips of their processes acquire a bulbous shape.
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