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  • 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
  • NMR
  • Solanaceae
  • Elsevier  (1.468)
  • Wiley-Blackwell  (365)
  • American Geophysical Union  (23)
  • AGU  (14)
  • Essen : Verl. Glückauf
  • Krefeld : Geologischer Dienst Nordhein-Westfalen
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  • 1
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    High-speed imaging of Strombolian explosions: The ejection velocity of pyroclasts (2015)
    American Geophysical Union
    Details
    Publikationsdatum: 2020-12-14
    Beschreibung: 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.
    Beschreibung: 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
    Beschreibung: Published
    Beschreibung: L02301
    Beschreibung: 3V. Dinamiche e scenari eruttivi
    Beschreibung: JCR Journal
    Beschreibung: open
    Schlagwort(e): 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)
    Materialart: article
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  • 2
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    High-speed imaging, acoustic features, and aeroacoustic computations of jet noise from Strombolian (and Vulcanian) explosions (2015)
    American Geophysical Union
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: 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.
    Beschreibung: 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
    Beschreibung: Published
    Beschreibung: 3096–3102
    Beschreibung: 3V. Dinamiche e scenari eruttivi
    Beschreibung: JCR Journal
    Beschreibung: restricted
    Schlagwort(e): 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)
    Materialart: article
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  • 3
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    First observations of the fumarolic gas output from a restless caldera: implications for the current period of unrest (2005-2013) at Campi Flegrei (2015)
    American Geophysical Union
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: 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.
    Beschreibung: Published
    Beschreibung: 4153–4169
    Beschreibung: 2V. Dinamiche di unrest e scenari pre-eruttivi
    Beschreibung: JCR Journal
    Beschreibung: restricted
    Schlagwort(e): 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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  • 4
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    Real-time measurements of the concentration and isotope composition of atmospheric and volcanic CO2 at Mount Etna (Italy) (2014)
    American Geophysical Union
    Details
    Publikationsdatum: 2020-02-24
    Beschreibung: We present unprecedented data of real-time measurements of the concentration and isotope composition of CO2 in air and in fumarole-plume gases collected in 2013 during two campaigns at Mount Etna volcano, which were made using a laser-based isotope ratio infrared spectrometer. We performed approximately 360 measurements/h, which allowed calculation of the δ13C values of volcanic CO2. The fumarole gases of Torre del Filosofo (2900mabove sea level) range from 3.24 ± 0.06‰to 3.71 ± 0.09‰, comparable to isotope ratio mass spectrometry (IRMS) measurements of discrete samples collected on the same dates. Plume gases sampled more than 1 km from the craters show a δ13C= 2.2 ± 0.4‰, in agreement with the crater fumarole gases analyzed by IRMS. Measurements performed along ~17km driving track from Catania to Mount Etna show more negative δ13C values when passing through populated centers due to anthropogenic-derived CO2 inputs (e.g., car exhaust). The reported results demonstrate that this technique may represent an important advancement for volcanic and environmental monitoring.
    Beschreibung: Published
    Beschreibung: 2382–2389
    Beschreibung: 2V. Dinamiche di unrest e scenari pre-eruttivi
    Beschreibung: JCR Journal
    Beschreibung: restricted
    Schlagwort(e): Real-time data of CO2 content and δ13C in atmospheric/volcanic gases ; This study opens new perspective for the community for 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 ; 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)
    Materialart: article
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  • 5
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    Regional groundwater flow and interactions with deep fluids in western Apennine: the case of Narni-Amelia chain (Central Italy) (2012)
    Wiley-Blackwell
    Details
    Publikationsdatum: 2021-01-07
    Beschreibung: The elemental fluxes and heat flow associated with large aquifer systems can be significant both at local and at regional scales. In fact, large amounts of heat transported by regional groundwater flow can affect the subsurface thermal regime, and the amount of matter discharged towards the surface by large spring systems can be significant relative to the elemental fluxes of surface waters. The Narni-Amelia regional aquifer system (Central Italy) discharges more than 13 m3 sec)1 of groundwater characterised by a slight thermal anomaly, high salinity and high pCO2. During circulation in the regional aquifer, groundwater reacts with the host rocks (dolostones, limestones and evaporites) and mixes with deep CO2-rich fluids of mantle origin. These processes transfer large amounts of dissolved substances, in particular carbon dioxide, and a considerable amount of heat towards the surface. Because practically all the water circulating in the Narni-Amelia system is discharged by few large springs (Stifone-Montoro), the mass and energy balance of these springs can give a good estimation of the mass and heat transported from the entire system towards the surface. By means of a detailed mass and balance of the aquifer and considering the soil CO2 fluxes measured from the main gas emission of the region, we computed a total CO2 discharge of about 7.8 · 109 mol a)1 for the whole Narni-Amelia system. Finally, considering the enthalpy difference between infiltrating water and water discharged by the springs, we computed an advective heat transfer related to groundwater flow of 410 ± 50 MW.
    Beschreibung: Published
    Beschreibung: 182-196
    Beschreibung: 2.4. TTC - Laboratori di geochimica dei fluidi
    Beschreibung: 4.5. Studi sul degassamento naturale e sui gas petroliferi
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): carbon dioxide degassing ; heat flow ; regional aquifer ; 04. Solid Earth::04.02. Exploration geophysics::04.02.01. Geochemical exploration ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 6
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    How do volcanic rift zones relate to flank instability? Evidence from collapsing rifts at Etna (2012)
    American Geophysical Union
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: Volcanic rift zones, characterized by repeated dike emplacements, are expected to delimit the upper portion of unstable flanks at basaltic edifices. We use nearly two decades of InSAR observations excluding wintertime acquisitions, to analyze the relationships between rift zones, dike emplacement and flank instability at Etna. The results highlight a general eastward shift of the volcano summit, including the northeast and south rifts. This steadystate eastward movement (1-2 cm/yr) is interrupted or even reversed during transient dike injections. Detailed analysis of the northeast rift shows that only during phases of dike injection, as in 2002, does the rift transiently becomes the upper border of the unstable flank. The flank's steady-state eastward movement is inferred to result from the interplay between magmatic activity, asymmetric topographic unbuttressing, and east-dipping detachment geometry at its base. This study documents the first evidence of steady-state volcano rift instability interrupted by transient dike injection at basaltic edifices.
    Beschreibung: Partially funded by INGV and the Italian DPC (DPC-INGV project V4 “Flank”). ERS and ENVISAT SAR data were provided by ESA through the Cat-1 project no. 4532 and the GEO Supersite initiative. The DEM was obtained from the SRTM archive. ERS-1/2 orbits are courtesy of the TU-Delft, The Netherlands. SAR data processing has been done at IREACNR, partially carried out under contract “Volcanic Risk System (SRV)” funded by the Italian Space Agency (ASI).
    Beschreibung: Published
    Beschreibung: L20311
    Beschreibung: 1.3. TTC - Sorveglianza geodetica delle aree vulcaniche attive
    Beschreibung: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Beschreibung: 1.10. TTC - Telerilevamento
    Beschreibung: 3.2. Tettonica attiva
    Beschreibung: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Beschreibung: 3.6. Fisica del vulcanismo
    Beschreibung: 4.3. TTC - Scenari di pericolosità vulcanica
    Beschreibung: JCR Journal
    Beschreibung: restricted
    Schlagwort(e): flank instability ; rift zones ; 04. Solid Earth::04.03. Geodesy::04.03.99. General or miscellaneous ; 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::04.03. Geodesy::04.03.07. Satellite geodesy ; 04. Solid Earth::04.03. Geodesy::04.03.09. Instruments and techniques ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.06. Rheology, friction, and structure of fault zones ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 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::04.08.06. 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::05.08. Risk::05.08.99. General or miscellaneous
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 7
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    Mapping and DOWNFLOW simulation of recent lava flow fields at Mount Etna (2012)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: In recent years, progress in geographic information systems (GIS) and remote sensing techniques have allowed the mapping and studying of lava flows in unprecedented detail. A composite GIS technique is introduced to obtain high resolution boundaries of lava flow fields. This technique is mainly based on the processing of LIDAR-derived maps and digital elevation models (DEMs). The probabilistic code DOWNFLOW is then used to simulate eight large flow fields formed at Mount Etna in the last 25 years. Thanks to the collection of 6 DEMs representing Mount Etna at different times from 1986 to 2007, simulated outputs are obtained by running the DOWNFLOW code over pre-emplacement topographies. Simulation outputs are compared with the boundaries of the actual flow fields obtained here or derived from the existing literature. Although the selected fields formed in accordance with different emplacement mechanisms, flowed on different zones of the volcano over different topographies and were fed by different lava supplies of different durations, DOWNFLOW yields results close to the actual flow fields in all the cases considered. This outcome is noteworthy because DOWNFLOW has been applied by adopting a default calibration, without any specific tuning for the new cases considered here. This extensive testing proves that, if the pre-emplacement topography is available, DOWNFLOW yields a realistic simulation of a future lava flow based solely on a knowledge of the vent position. In comparison with deterministic codes, which require accurate knowledge of a large number of input parameters, DOWNFLOW turns out to be simple, fast and undemanding, proving to be ideal for systematic hazard and risk analyses.
    Beschreibung: Published
    Beschreibung: 27-39
    Beschreibung: 4.3. TTC - Scenari di pericolosità vulcanica
    Beschreibung: 5.5. TTC - Sistema Informativo Territoriale
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): LIDAR ; lava flow field ; lava flow simulation ; Digital elevation model ; Mount Etna ; 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)
    Materialart: article
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  • 8
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    Texture analysis of volcanic rock samples: Quantitative study of crystals and vesicles shape preferred orientation from X-ray microtomography data (2012)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: In the texture analysis of volcanic rocks, the preferred orientation of the constituents can provide useful information for the interpretation of the processes involved in the rock formation. We present here a new data analysis technique, based on X-ray microtomography measurements and on shape preferred orientation analysis, to obtain the orientation distribution functions of the constituents of volcanic rocks. This procedure proved to be very suitable for volcanic samples, where diffraction-based techniques, developed for crystallographic preferred orientation studies, are of limited utilization, in addition to the fact that they cannot provide any information about vesicles or bubbles. Moreover the analysis performed directly in three dimensions (3D) overcomes the problems that usually occur when employing stereological methods for the analysis of the images obtained via microscopy-based techniques. In this study, two scoriae (from Stromboli and Etna) and a tube pumice (from Campi Flegrei) were measured via X-ray microtomography and then the resulting volumes were analyzed following the proposed procedure. Results highlight little preferred orientation for the vesicles in the two scoria samples, whereas the pumice shows a marked preferred orientation. Crystals (also divided by mineral species) were taken into account as well and in the two scoria samples there is no crystal preferred orientation, in contrast with the pumice, where crystal preferred orientation features are very similar to the ones found for the vesicles. Overall we found strong differences in preferred orientation: weak for vesicles in scoriae, showing an axial symmetry with the axis parallel to the elongation axis of the sample, and a stronger and more complex orientation texture in the pumice sample for both crystals and vesicles. The promising results obtained suggest that this procedure is potentially very useful for the analysis of preferred orientation in volcanic rocks and geomaterials in general.
    Beschreibung: Published
    Beschreibung: 83-95
    Beschreibung: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): X-ray computed microtomography ; preferred orientation ; texture analysis ; volcanic scoria ; synchrotron X-rays ; pumice ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 9
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    Geophysical and geochemical survey of a large marine pockmark on the Malin Shelf, Ireland (2012)
    American Geophysical Union
    Details
    Publikationsdatum: 2022-05-25
    Beschreibung: Author Posting. © American Geophysical Union, 2012. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry Geophysics Geosystems 13 (2012): Q01011, doi:10.1029/2011GC003787.
    Beschreibung: Marine pockmarks are a specific type of seabed geological setting resembling craters or pits and are considered seabed surface expressions of fluid flow in the subsurface. A large composite pockmark on the Malin Shelf, off the northern coast of Ireland was surveyed and ground truthed to assess its activity and investigate fluid related processes in the subsurface. Geophysical (including acoustic and electromagnetic) data confirmed the subsurface presence of signatures typical of fluids within the sediment. Shallow seismic profiling revealed a large shallow gas pocket and typical gas related indicators such as acoustic blanking and enhanced reflectors present underneath and around the large pockmark. Sulphate profiles indicate that gas from the shallow reservoir has been migrating upwards, at least recently. However, there are no chimney structures observed in the sub-bottom data and the migration pathways are not apparent. Electromagnetic data show slightly elevated electrical conductivity on the edges of the pockmarks and a drop below regional levels within the confines of the pockmark, suggesting changes in physical properties of the sediment. Nuclear Magnetic Resonance (NMR) experiments were employed to characterize the organic component of sediments from selected depths. Very strong microbial signatures were evident in all NMR spectra but microbes outside the pockmark appear to be much more active than inside. These observations coincide with spikes in conductivity and the lateral gas bearing body suggesting that there is an increase in microbial activity and biomass when gas is present.
    Beschreibung: We wish to thank the Geological Survey of Ireland, the INtegrated Mapping FOr the Sustainable Development of Ireland’s MArine Resource (INFOMAR) program, the Irish Environmental Protection Agency, Science Foundation of Ireland, QUESTOR (Queens University Belfast) and the Irish Council for Science, engineering and technology for funding this research. AJS thanks NSERC, (Strategic and Discovery Programs), the Canada Foundation for Innovation (CFI), and the Ministry of Research and Innovation (MRI) for providing Canadian funding. The survey data utilized in the research has been co‐funded by the Geological Survey of Ireland and the Offshore Irish Petroleum Infrastructure Programme (PIP; Ref. No: IS05/16 Malin Basin EM).
    Beschreibung: 2012-07-19
    Schlagwort(e): Malin Shelf ; NMR ; Electromagnetic ; Microbial ; Organic matter ; Pockmark
    Repository-Name: Woods Hole Open Access Server
    Materialart: Article
    Format: application/pdf
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  • 10
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    Tephra sedimentation during the 2010 Eyjafjallajökull eruption (Iceland) from deposit, radar, and satellite observations (2012)
    American Geophysical Union
    Details
    Publikationsdatum: 2023-01-16
    Beschreibung: The April–May 2010 eruption of the Eyjafjallajökull volcano (Iceland) was characterized by a nearly continuous injection of tephra into the atmosphere that affected various economic sectors in Iceland and caused a global interruption of air traffic. Eruptive activity during 4–8 May 2010 was characterized based on short-duration physical parameters in order to capture transient eruptive behavior of a long-lasting eruption (i.e., total grain-size distribution, erupted mass, and mass eruption rate averaged over 30 min activity). The resulting 30 min total grain-size distribution based on both ground and Meteosat Second Generation-Spinning Enhanced Visible and Infrared Imager (MSG-SEVIRI) satellite measurements is characterized by Mdphi of about 2 and a fine-ash content of about 30 wt %. The accumulation rate varied by 2 orders of magnitude with an exponential decay away from the vent, whereas Mdphi shows a linear increase until about 18 km from the vent, reaching a plateau of about 4.5 between 20 and 56 km. The associated mass eruption rate is between 0.6 and 1.2 × 105 kg s−1. In situ sampling showed how fine ash mainly fell as aggregates of various typologies. About 5 to 9 wt % of the erupted mass remained in the cloud up to 1000 km from the vent, suggesting that nearly half of the ash 〉7 settled as aggregates within the first 60 km. Particle sphericity and shape factor varied between 0.4 and 1 with no clear correlation to the size and distance from vent. Our experiments also demonstrate how satellite retrievals and Doppler radar grain-size detection can provide a real-time description of the source term but for a limited particle-size range.
    Beschreibung: Published
    Beschreibung: B12202
    Beschreibung: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): MSG-SEVIRI, PLUDIX ; particle aggregation ; settling velocity ; tephra deposits ; weak plumes ; 04. Solid Earth::04.04. Geology::04.04.06. Rheology, friction, and structure of fault zones ; 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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  • 11
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    Volcanic ash and SO2 in the 2008 Kasatochi eruption: Retrievals comparison from different IR satellite sensors (2011)
    AGU
    Details
    Publikationsdatum: 2012-02-03
    Beschreibung: The Kasatochi 2008 eruption was detected by several infrared satellite sensors including Moderate Resolution Imaging Spectroradiometer (MODIS), Advanced Very High Resolution Radiometer (AVHRR), and Atmospheric Infrared Sounder (AIRS). In this work a comparison between the volcanic cloud SO2 and ash retrievals derived from these instruments has been undertaken. The SO2 retrieval is carried out by using both the 7.3 and 8.7 micron absorption features while ash retrieval exploits the 10–12 micron atmospheric window. A radiative transfer scheme is also used to correct the volcanic ash effect on the 8.7 micron SO2 signature. As test cases, three near‐contemporary images for each sensor, collected during the first days of the eruption, have been analyzed. The results show that the volcanic SO2 and ash are simultaneously present and generally collocated. The MODIS and AVHRR total ash mass loadings are in good agreement and estimated to be about 0.5 Tg, while the AIRS retrievals are slightly lower and equal to about 0.3 Tg. The AIRS and MODIS 7.3 micron SO2 mass loadings are also in good agreement and vary between 0.3 and 1.2 Tg, while the MODIS ash corrected 8.7 micron SO2 masses vary between 0.4 and 2.7 Tg. The mass increase with time confirms the continuous SO2 injection in the atmosphere after the main explosive episodes. Moreover the difference between the 7.3 and 8.7 micron retrievals suggests a vertical stratification of the volcanic cloud. The results also confirm the importance of the ash correction; the corrected 8.7 micron SO2 total masses are less than 30–40% of the uncorrected values.
    Beschreibung: Published
    Beschreibung: D00L21
    Beschreibung: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Beschreibung: 1.10. TTC - Telerilevamento
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): Remote sensing ; ash retrieval ; SO2 retrieval ; multispectral satellite instruments ; MODIS ; AVHRR ; AIRS ; hyperspectral satellite instruments ; 01. Atmosphere::01.01. Atmosphere::01.01.07. Volcanic effects ; 01. Atmosphere::01.01. Atmosphere::01.01.08. Instruments and techniques ; 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)
    Materialart: article
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  • 12
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    A relation between lava discharge rate, thermal insulation, and flow area set using lidar data (2011)
    American Geophysical Union
    Details
    Publikationsdatum: 2012-02-03
    Beschreibung: A simple linear relation can be used to link time averaged discharge rate (TADR) and lava flow area (A). The relation applies to given insulation conditions, as described by the characteristic flow surface temperature (Te), and will vary from case-to-case depending on rheological and topographic influences on flow spreading. Most flows have insulation conditions that change through time, modifying the relationship between TADR and area as insulation conditions evolve. Using lidar data we can define TADR, the flow area that the discharge feeds and Te, allowing generation of a case-specific relation to convert satellite-data-derived flow areas to TADR. For Etna's 2006 lava flow field we obtain a relation whereby TADR = 5.6 × 10−6 A for well insulated conditions (Te = 100°C) and TADR = 1.5 × 10−4 A for poorly insulated conditions (Te = 600°C).
    Beschreibung: Published
    Beschreibung: L20308
    Beschreibung: 1.10. TTC - Telerilevamento
    Beschreibung: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Beschreibung: 3.6. Fisica del vulcanismo
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): lava flow ; discharge rate ; area ; surface temperature ; lidar ; Etna. ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 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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  • 13
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    Societal need for improved understanding of climate change, anthropogenic impacts, and geo-hazard warning drive development of ocean observatories in European Seas (2011)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: Society’s needs for a network of in situ ocean observing systems cross many areas of earth and marine science. Here we review the science themes that benefit from data supplied from ocean observatories. Understanding from existing studies is fragmented to the extent that it lacks the coherent long-term monitoring needed to address questions at the scales essential to understand climate change and improve geo-hazard early warning. Data sets from the deep sea are particularly rare with long-term data available from only a few locations worldwide. These science areas have impacts on societal health and well-being and our awareness of ocean function in a shifting climate. Substantial efforts are underway to realise a network of open-ocean observatories around European Seas that will operate over multiple decades. Some systems are already collecting high-resolution data from surface, water column, seafloor, and sub-seafloor sensors linked to shore by satellite or cable connection in real or near-real time, along with samples and other data collected in a delayed mode. We expect that such observatories will contribute to answering major ocean science questions including: How can monitoring of factors such as seismic activity, pore fluid chemistry and pressure, and gas hydrate stability improve seismic, slope failure, and tsunami warning? What aspects of physical oceanography, biogeochemical cycling, and ecosystems will be most sensitive to climatic and anthropogenic change? What are natural versus anthropogenic changes? Most fundamentally, how are marine processes that occur at differing scales related? The development of ocean observatories provides a substantial opportunity for ocean science to evolve in Europe. Here we also describe some basic attributes of network design. Observatory networks provide the means to coordinate and integrate the collection of standardised data capable of bridging measurement scales across a dispersed area in European Seas adding needed certainty to estimates of future oceanic conditions. Observatory data can be analysed along with other data such as those from satellites, drifting floats, autonomous underwater vehicles, model analysis, and the known distribution and abundances of marine fauna in order to address some of the questions posed above. Standardised methods for information management are also becoming established to ensure better accessibility and traceability of these data sets and ultimately to increase their use for societal benefit. The connection of ocean observatory effort into larger frameworks including the Global Earth Observation System of Systems (GEOSS) and the Global Monitoring of Environment and Security (GMES) is integral to its success. It is in a greater integrated framework that the full potential of the component systems will be realised.
    Beschreibung: Published
    Beschreibung: 1-33
    Beschreibung: 3.7. Dinamica del clima e dell'oceano
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): Seafloor and water columnobservatories ; 01. Atmosphere::01.01. Atmosphere::01.01.02. Climate ; 01. Atmosphere::01.01. Atmosphere::01.01.04. Processes and Dynamics ; 01. Atmosphere::01.01. Atmosphere::01.01.08. Instruments and techniques ; 03. Hydrosphere::03.01. General::03.01.03. Global climate models ; 03. Hydrosphere::03.01. General::03.01.07. Physical and biogeochemical interactions ; 03. Hydrosphere::03.01. General::03.01.08. Instruments and techniques ; 03. Hydrosphere::03.03. Physical::03.03.01. Air/water/earth interactions ; 03. Hydrosphere::03.03. Physical::03.03.02. General circulation ; 03. Hydrosphere::03.03. Physical::03.03.03. Interannual-to-decadal ocean variability ; 03. Hydrosphere::03.03. Physical::03.03.05. Instruments and techniques ; 03. Hydrosphere::03.04. Chemical and biological::03.04.01. Biogeochemical cycles ; 03. Hydrosphere::03.04. Chemical and biological::03.04.02. Carbon cycling ; 03. Hydrosphere::03.04. Chemical and biological::03.04.03. Chemistry of waters ; 03. Hydrosphere::03.04. Chemical and biological::03.04.04. Ecosystems ; 03. Hydrosphere::03.04. Chemical and biological::03.04.05. Gases ; 03. Hydrosphere::03.04. Chemical and biological::03.04.06. Hydrothermal systems ; 03. Hydrosphere::03.04. Chemical and biological::03.04.08. Instruments and techniques ; 04. Solid Earth::04.01. Earth Interior::04.01.02. Geological and geophysical evidences of deep processes ; 04. Solid Earth::04.04. Geology::04.04.04. Marine geology ; 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::04.05. Geomagnetism::04.05.05. Main geomagnetic field ; 04. Solid Earth::04.05. Geomagnetism::04.05.08. Instruments and techniques ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring ; 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::04.07. Tectonophysics::04.07.02. Geodynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.03. Heat generation and transport ; 04. Solid Earth::04.07. Tectonophysics::04.07.04. Plate boundaries, motion, and tectonics ; 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::04.08.02. Experimental volcanism ; 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::05.01. Computational geophysics::05.01.01. Data processing ; 05. General::05.02. Data dissemination::05.02.99. General or miscellaneous ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data ; 05. General::05.02. Data dissemination::05.02.02. Seismological data ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions ; 05. General::05.02. Data dissemination::05.02.04. Hydrogeological data ; 05. General::05.08. Risk::05.08.01. Environmental risk ; 05. General::05.08. Risk::05.08.02. Hydrogeological risk
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  • 14
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    The regular shape of stratovolcanoes: A DEM-based morphometrical approach (2011)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: We studied the shape of the most regular-shaped stratovolcanoes of the world to mathematically define the form of the ideal stratovolcano. Based on the Shuttle Radar Topographic Mission data we selected 19 of the most circular and symmetrical volcanoes, which incidentally all belong to subduction-related arcs surrounding the Pacific. The selection of volcanoes benefitted from the introduction of a new definition of circularity which is more robust than previous definitions, being independent of the erosional dissection of the cone. Our study on the shape of stratovolcanoes was based on the analysis of the radial elevation profiles of each volcano. The lower half section of the volcanoes is always well fitted by a logarithmic curve, while the upper half section is not, and falls into two groups: it is fitted either by a line (“C-type”, conical upper part) or by a parabolic arc (“P-type”, parabolic/concave upper part). A quantitative discrimination between these groups is obtained by fitting their upper slope with a linear function: C-type volcanoes show small, whereas P-type volcanoes show significant negative angular coefficient. The proposed threshold between the two groups is − 50 × 10− 4°/m. Chemical composition of eruptive products indicates higher SiO2 and/or higher H2O content for C-type volcanoes, which could imply a higher incidence of mildly explosive (e.g. strombolian) eruptions. We propose that this higher explosivity is responsible for forming the constant uppermost slopes by the deposition of ballistic tephra and its subsequent stabilisation at a constant angle. By contrast, P-type volcanoes are characterized by a smaller SiO2 and H2O content, which can be responsible for a higher incidence of effusive events and/or a lower incidence of upper flank-forming (i.e. mild) explosive eruptions. Therefore, the concave upper flanks of these volcanoes may be shaped typically by lava flows. Based on this hypothesis, we propose that the morphometric analysis of the elevation profile of stratovolcanoes can provide insights into their dominant eruptive style.
    Beschreibung: Published
    Beschreibung: 171-181
    Beschreibung: 1.10. TTC - Telerilevamento
    Beschreibung: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Beschreibung: 3.6. Fisica del vulcanismo
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): stratovolcano ; SRTM ; shape analysis ; elevation profile ; circularity ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 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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  • 15
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    Adventive hydrothermal circulation on Stromboli volcano (Aeolian Islands, Italy) revealed by geophysical and geochemical approaches: Implications for general fluid flow models on volcanoes (2011)
    Elsevier
    Details
    Publikationsdatum: 2022-06-13
    Beschreibung: On March 15th 2007 a paroxysmal explosion occurred at the Stromboli volcano. This event generated a large amount of products,mostly lithic blocks, someofwhich impacted the ground as far as down to 200 m a.s.l., about 1.5 kmfaraway fromthe active vents. Two days after the explosion, a newvapouremissionwas discovered on the north-eastern flank of the volcanic edifice, at 560 m a.s.l., just above the area called “Nel Cannestrà”. This new vapour emission was due to a block impact. In order to investigate the block impact area to understand the appearance of the vapour emission, we conducted on May 2008 a multidisciplinary study involving Electrical Resistivity Tomography (ERT), Ground Penetrating Radar (GPR), Self-Potential (SP), CO2 soil diffuse degassing and soil temperature surveys. This complementary data set revealed the presence of an anomalous conductive body, probably related to a shallow hydrothermal level, at about 10–15 m depth, more or less parallel to the topography. It is the first time that such a hydrothermal fluid flow,with a temperature close to thewater boiling point (76 °C) has been evidenced at Stromboli at this low elevation on the flank of the edifice. The ERT results suggest a possible link between (1) the main central hydrothermal system of Stromboli, located just above the plumbing system feeding the active vents, with a maximum of subsurface soil temperature close to 90 °C and limited by the NeoStromboli summit crater boundary and (2) the investigated area of Nel Cannestrà, at ~500 m a.s.l., a buried eruptive fissure active 9 ka ago. In parallel, SP and CO2 soil diffuse degassingmeasurements suggest in this sector at slightly lower elevation fromthe block impact crater a magmatic and hydrothermal fluid rising system along the N41° regional fault. A complementary ERT profile, on May 2009, carried out from the NeoStromboli crater boundary downto the block impact crater displayed a flank fluid flowapparently connected to a deeper system. The concept of shallow hydrothermal level have been compared to similar ERT results recently obtained onMount Etna and La Fossa cone of Vulcano. This information needs to be taken into account in general fluid flow models on volcanoes. In particular, peripheral thermal waters (as those bordering the northeastern coast of Stromboli) could be contaminated by hydrothermal and magmatic fluids coming from regional faults but also from the summit.
    Beschreibung: Published
    Beschreibung: 111-119
    Beschreibung: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Beschreibung: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): Stromboli ; hydrothermal system ; adventive hydrothermal flow ; electrical resistivity tomography ; self-potential ; soil diffuse degassing ; temperature ; 2007 Stromboli eruptive crisis ; 04. Solid Earth::04.08. Volcanology::04.08.04. Thermodynamics ; 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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  • 16
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    Nitrogen Isotopes in Volcanic Fluids of Different Geodynamic Settings (2010)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: Nitrogen isotopes , N2/36Ar and 3He/4He were measured in volcanic fluids within different geodynamic settings. Subduction zones are represented by Aeolian archipelago, Mexican volcanic belt and Hellenic arc, spreading zones – by Socorro island in Mexico and Iceland and hot spots by Iceland and Islands of Cabo Verde. The δ15N values, corrected for air contamination of volcanic fluids, discharged from Vulcano Island (Italy), highlighted the presence of heavy nitrogen (around +4.3 ±0.5‰). Similar 15N values (around +5‰), have been measured for the fluids collected in the Jalisco Block, that is a geologically and tectonically complex forearc zone of the northwestern Mexico [1]. Positive values (15N around +3‰) have been also measured in the volcanic fluids discharged from Nysiros island located in the Ellenic Arc characterized by subduction processes. All uncorrected data for the Socorro island are in the range of -1 to -2‰. The results of raw nitrogen isotope data of Iceland samples reveal more negative isotope composition (about -4.4‰). On the basis of the non-atmospheric N2 fraction (around 50%) the corrected data of 15N for Iceland are around -16‰, very close to the values proposed by [2]. In a volcanic gas sample from Fogo volcano (Cabo Verde islands) we found a very negative value: -9.9‰ and -15‰ for raw and corrected values, respectively.
    Beschreibung: Published
    Beschreibung: Davos, Switzerland
    Beschreibung: 2.4. TTC - Laboratori di geochimica dei fluidi
    Beschreibung: open
    Schlagwort(e): Nitrogen Isotopes ; Subduction ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: Poster session
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  • 17
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    Topographic control on lava flow paths at Mount Etna, Italy: Implications for hazard assessment (2010)
    American Geophysical Union
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: Assessment of the hazard from lava flow inundation at the active volcano of Mount Etna, Italy, was performed by calculating the probability of lava flow inundation at each position on the volcano. A probability distribution for the formation of new vents was calculated using geological and volcanological data from past eruptions. The simulated lava flows from these vents were emplaced using a maximum expected flow length derived from geological data on previous lava flows. Simulations were run using DOWNFLOW, a digital-elevation-model-based model designed to predict lava flow paths. Different eruptive scenarios were simulated by varying the elevation and probability distribution of eruptive points. Inundation maps show that the city of Catania and the coastal zone may only be impacted by flows erupted from low-altitude vents (〈1500 m elevation) and that flank eruptions at elevations 〉2000 m preferentially inundate the northeast and southern sectors of the volcano as well as the Valle del Bove. Eruptions occurring in the summit area (〉3000 m elevation) pose no threat to the local population. Discrepancies between the results of simple, hydrological models and those of the DOWNFLOW model show that hydrological approaches are inappropriate when dealing with Etnean lava flows. Because hydrological approaches are not designed to reproduce the full complexity of lava flow spreading, they underestimate the catchment basins when the fluid has a complex rheology.
    Beschreibung: Published
    Beschreibung: F01019
    Beschreibung: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Beschreibung: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Beschreibung: 4.3. TTC - Scenari di pericolosità vulcanica
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): volcanic hazard ; lava flow ; Mount Etna ; 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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  • 18
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    Morphometry of scoria cones located on a volcano flank: A case study from Mt. Etna (Italy), based on high-resolution LiDAR data (2010)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: By using new high-resolution (2 m) digital elevation model derived from the 2005 LiDAR survey of Mt. Etna volcano (Italy), our study measured the classical morphometrical parameters for scoria cones, i.e. Wco (cone width), Wcr (crater diameter), H (cone height) as well as volume, inclination of cone slope and substrate, and a number of other parameters for 135 scoria cones of Mt. Etna. Volume and age distribution of cones shows that there is no direct structural control on their emplacement in terms of Etna's rift zones. The cones are progressively smaller in size toward summit, which can be explained by the large volcano's feeding system and progressively frequent lava burial toward top. A careful analysis of H/Wco ratio (determined as 0.18 for other volcanic fields worldwide) shows that this ratio strongly depends on (1) the calculation method of H and (2) lava burial of cone. For Etnean cones, applying an improved method for calculating H relative to the dipping substrate results in a significantly lowered standard H/Wco ratio (0.137), which in turn questions the validity of the classical value of 0.18 in the case of large central volcanoes. The reduction of the ratio is not only due to methodology but also to the common lava burial. This can be expressed even better if Hmean is used instead of Hmax (Hmean/Wco = 0.098). Using this measure, at Etna, well formed cones have higher ratios than structurally deformed (e. g. double or rifted) cones. Furthermore, although the sampled scoria cones at Etna have formed in a relatively narrow time interval (〈 6500 yrs BP), there is a slight decrease in H/Wco corresponding to erosional changes detected globally (H/Wco = 0.143, 0.135 and 0.115 for three age classes of Etna's scoria cones, corresponding to average slopes of 26.6, 23.9 and 23.7°). Because the morphometrical effect of position on a dipping substrate as well as lava burial exceeds the effect of erosion, we call attention to use caution in simply using the H/Wco ratio of scoria cones for detecting age, especially on large active volcanoes.
    Beschreibung: Published
    Beschreibung: 320-330
    Beschreibung: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Beschreibung: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): scoria cone ; morphometry ; Etna ; H/Wco ratio ; DEM analysis ; 04. Solid Earth::04.04. Geology::04.04.03. Geomorphology ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques ; 05. General::05.06. Methods::05.06.99. General or miscellaneous
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  • 19
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    LIDAR strip adjustment: Application to volcanic areas (2010)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: DEMs derived from LIDAR data are nowadays largely used for quantitative analyses and modelling in geology and geomorphology. High-quality DEMs are required for the accurate morphometric and volumetric measurement of land features. We propose a rigorous automatic algorithm for correcting systematic errors in LIDAR data in order to assess sub-metric variations in surface morphology over wide areas, such as those associated with landslide, slump, and volcanic deposits. Our procedure does not require a priori knowledge of the surface, such as the presence of known ground control points. Systematic errors are detected on the basis of distortions in the areas of overlap among different strips. Discrepancies between overlapping strips are assessed at a number of chosen computational tie points. At each tie point a local surface is constructed for each strip containing the point. Displacements between different strips are then calculated at each tie point, and minimization of these discrepancies allows the identification of major systematic errors. These errors are identified as a function of the variables that describe the data acquisition system. Significant errors mainly caused by a non-constant misestimation of the roll angle are highlighted and corrected. Comparison of DEMs constructed using first uncorrected and then corrected LIDAR data from different Mt. Etna surveys shows a meaningful improvement in quality: most of the systematic errors are removed and the accuracy of morphometric and volumetric measurements of volcanic features increases. These corrections are particularly important for the following studies of Mt. Etna: calculation of lava flow volume; calculation of erosion and deposition volume of pyroclastic cones; mapping of areas newly covered by volcanic ash; and morphological evolution of a portion of an active lava field over a short time span.
    Beschreibung: Published
    Beschreibung: 123-135
    Beschreibung: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Beschreibung: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): LIDAR ; Calibration ; DEM ; Etna ; 04. Solid Earth::04.04. Geology::04.04.03. Geomorphology ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques ; 05. General::05.06. Methods::05.06.99. General or miscellaneous
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  • 20
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    Patterns in the recent 2007–2008 activity of Mount Etna volcano investigated by integrated geophysical and geochemical observations (2010)
    American Geophysical Union
    Details
    Publikationsdatum: 2012-02-03
    Beschreibung: An edited version of this paper was published by AGU. Copyright (2010) American Geophysical Union
    Beschreibung: Seismic, deformation, and volcanic gas observations offer independent and complementary information on the activity state and dynamics of quiescent and eruptive volcanoes and thus all contribute to volcanic risk assessment. In spite of their wide use, there have been only a few efforts to systematically integrate and compare the results of these different monitoring techniques. Here we combine seismic (volcanic tremor and long‐period seismicity), deformation (GPS), and geochemical (volcanic gas plume CO2/SO2 ratios) measurements in an attempt to interpret trends in the recent (2007–2008) activity of Etna volcano. We show that each eruptive episode occurring at the Southeast Crater (SEC) was preceded by a cyclic phase of increase‐decrease of plume CO2/SO2 ratios and by inflation of the volcano’s summit captured by the GPS network. These observations are interpreted as reflecting the persistent supply of CO2‐rich gas bubbles (and eventually more primitive magmas) to a shallow (depth of 1–2.8 km asl) magma storage zone below the volcano’s central craters (CCs). Overpressuring of the resident magma stored in the upper CCs’ conduit triggers further magma ascent and finally eruption at SEC, a process which we capture as an abrupt increase in tremor amplitude, an upward (〉2800 m asl) and eastward migration of the source location of seismic tremor, and a rapid contraction of the volcano’s summit. Resumption of volcanic activity at SEC was also systematically anticipated by declining plume CO2/SO2 ratios, consistent with magma degassing being diverted from the central conduit area (toward SEC).
    Beschreibung: Published
    Beschreibung: Q09008
    Beschreibung: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Beschreibung: 1.3. TTC - Sorveglianza geodetica delle aree vulcaniche attive
    Beschreibung: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): volcano monitoring ; Mt. Etna volcano ; geochemistry and geophysics ; volcanic tremor ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 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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  • 21
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    Coupled Use of COSPEC and Satellite Measurements to define the Volumetric Balance During Effusive Eruptions at Mt. Etna, Italy (2010)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: Mt. Etna is one of the most studied and extensively monitored volcanoes on earth (Bonaccorso et al., 2004). One of the most frequent hazards are due to the eruption of lava flows, more specifically those flows produced during flank eruptions. These eruptions potentially can produce extensive flows that can inundate densely populated communities of the lower slopes (Guest and Murray, 1979; Behncke et al., 2005). Satellite remote sensing can be used during effusive eruptions to help monitoring the volcano, by determining effusion rates of the flows, aiding in hazard management. The degassing that takes place when magma is rising to the surface can be regularly monitored using ultraviolet spectroscopic methods (e.g. Andres et al., 2001, Sutton et al., 2001). Sulfur Dioxide (SO2) fluxes have been derived from correlation spectrometer (COSPEC) measurements at Mt. Etna (Italy) on a regular basis since 1987 (e.g. Caltabiano et al., 1994; Allard, 1997; Andronico et al., 2005; Burton et al., 2005; Burton et al., in press). Previous studies have compared field-based effusion rates with the measured SO2 fluxes to determine how much of the degassed magma is erupted onto Etna’s flanks in the form of lava flows (Allard, 1997; Harris et al., 2000). However, most of these studies examine bulk volumes erupted over an eruption rather than examining the short-term variations during eruptions. Determining the amount of lava erupted and/or the balance between the amount supplied and the amount erupted remains an unresolved issue. The main objectives of this paper are to examine such short-term variations using satellite-based effusion rates along with regularly measured SO2 fluxes. Using these measurements we determine how and when the volume of supplied magma is balanced by the volume of erupted lava during individual effusive eruptions.
    Beschreibung: In press
    Beschreibung: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Beschreibung: JCR Journal
    Beschreibung: restricted
    Schlagwort(e): Etna ; Thermal Remote Sensing ; SO2 ; Mass Balance ; Effusive Eruptions ; 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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  • 22
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    Unbekannt
    Regional magnetic and gravity anomaly correlations of the Southern Tyrrhenian Sea (2010)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: The complex magnetic and gravity anomaly fields of the Southern Tyrrhenian Sea provide a record of the complicated properties and evolution of the underlying crust. Geologic interpretation of these anomalies is hindered by the effects of anomaly superposition and source ambiguity inherent to potential field analysis. A common approach to minimizing interpretational ambiguities is to consider analyses of anomaly correlations. Spectral correlation filters are used to separate positively and negatively correlated anomaly features based on the correlation coefficient given by the cosine of the phase difference between common wavenumber components. This procedure is applied to reduced-to-pole magnetic and first vertical derivative gravity anomalies for mapping correlative crustal magnetization and density contrasts. Adding and subtracting the standardized outputs of the filters yield summed (SLFI) and differenced (DLFI) local favorability indices that, respectively highlight positive and negative feature correlations in the anomaly data sets. Correlative maxima mainly reflect volcanic structures, and secondarily intrusive bodies and pre- Tortonian carbonates of the Maghrebian chain and the basement rocks of the Sardinia eastern margin. Correlative minima mostly mark sediment-filled peri-Tyrrhenian structural basins related to the Pliocene extensional tectonics, and intra-slope marine depressions related to post-Pliocene and still-active compressional tectonics off Northern Sicily. Prominent inverse anomaly correlations mainly reflect crustal features around the southern margin of the Tyrrhenian Sea that include higher density, lower magnetization pelagic-to-terrigenous and flysch-type nappes of the Sicilian-Maghrebian chain, as well as lower density, higher magnetization sediments filling depressions of the chain, and syn-rift sediments of Southeastern Sardinia.
    Beschreibung: Published
    Beschreibung: 27-41
    Beschreibung: 3.2. Tettonica attiva
    Beschreibung: 3.4. Geomagnetismo
    Beschreibung: 5.7. Consulenze in favore di istituzioni nazionali e attività nell'ambito di trattati internazionali
    Beschreibung: JCR Journal
    Beschreibung: restricted
    Schlagwort(e): Magnetism ; Gravity ; Modelling ; Back-arc basin ; Volcanism ; Tectonics ; Tyrrhenian Sea ; 04. Solid Earth::04.02. Exploration geophysics::04.02.99. General or miscellaneous ; 04. Solid Earth::04.05. Geomagnetism::04.05.04. Magnetic anomalies ; 04. Solid Earth::04.07. Tectonophysics::04.07.08. Volcanic arcs ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 23
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    Unbekannt
    Detachment depth revealed by rollover deformation: An integrated approach at Mount Etna (2010)
    American Geophysical Union
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: Flank instability is common at volcanoes, even though the subsurface structures, including the depth to a detachment fault, remain poorly constrained. Here, we use a multidisciplinary approach, applicable to most volcanoes, to evaluate the detachment depth of the unstable NE flank of Mt. Etna. InSAR observations of Mount Etna during 1995–2008 show a trapdoor subsidence of the upper NE flank, with a maximum deformation against the NE Rift. The trapdoor tilt was highest in magnitude in 2002–2004, contemporaneous with the maximum rates of eastward slip along the east flank. We explain this deformation as due to a general eastward displacement of the flank, activating a rotational detachment and forming a rollover anticline, the head of which is against the NE Rift. Established 2D rollover construction models, constrained by morphological and structural data, suggest that the east‐dipping detachment below the upper NE flank lies at around 4 km below the surface. This depth is consistent with seismicity that clusters above 2–3 km below sea level. Therefore, the episodically unstable NE flank lies above an east‐dipping rotational detachment confined by the NE Rift and Pernicana Fault. Our approach, which combines short‐term (InSAR) and long‐term (geological) observations, constrains the 3D geometry and kinematics of part of the unstable flank of Etna and may be applicable and effective to understand the deeper structure of volcanoes undergoing flank instability or unrest.
    Beschreibung: This work was partially funded by INGV and the DPC‐INGV project “Flank”, and partially by the ASI (SRV project).
    Beschreibung: Published
    Beschreibung: L16304
    Beschreibung: 1.3. TTC - Sorveglianza geodetica delle aree vulcaniche attive
    Beschreibung: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Beschreibung: 1.10. TTC - Telerilevamento
    Beschreibung: 3.2. Tettonica attiva
    Beschreibung: 4.3. TTC - Scenari di pericolosità vulcanica
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): flank instability ; fault ; InSAR ; Etna ; rollover ; 04. Solid Earth::04.01. Earth Interior::04.01.99. General or miscellaneous ; 04. Solid Earth::04.02. Exploration geophysics::04.02.99. General or miscellaneous ; 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::04.04.06. Rheology, friction, and structure of fault zones ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.04. Geology::04.04.11. Instruments and techniques ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous ; 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::04.08.06. 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::05.08. Risk::05.08.99. General or miscellaneous
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 24
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    Unbekannt
    Carbon dioxide of Pu`u`O`o volcanic plume at Kilauea retrieved by AVIRIS hyperspectral data (2009)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: A remote sensing approach permits for the first time the derivation of a map of the carbon dioxide concentration in a volcanic plume. The airborne imaging remote sensing overcomes the typical difficulties associated with the ground measurements and permits rapid and large views of the volcanic processes together with the measurements of volatile components exolving from craters. Hyperspectral images in the infrared range (1900–2100 nm), where carbon dioxide absorption lines are present, have been used. These images were acquired during an airborne campaign by the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) over the Pu`u` O`o Vent situated at the Kilauea East Rift zone, Hawaii. Using a radiative transfer model to simulate the measured up-welling spectral radiance and by applying the newly developed mapping technique, the carbon dioxide concentration map of the Pu`u` O`o Vent plume were obtained. The carbon dioxide integrated flux rate were calculated and a mean value of 396±138 t d−1 was obtained. This result is in agreement, within the measurements errors, with those of the ground measurements taken during the airborne campaign.
    Beschreibung: Published
    Beschreibung: 3192–3199
    Beschreibung: 1.10. TTC - Telerilevamento
    Beschreibung: JCR Journal
    Beschreibung: partially_open
    Schlagwort(e): Hyperspectral data ; Volcanic plume ; Carbon dioxide ; AVIRIS ; Kilauea ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 25
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    Unbekannt
    Insight on recent Stromboli eruption inferred from terrestrial and satellite ground deformation measurements (2009)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: The multi-parametric permanent system (tilt and GPS networks, robotized geodetic station) for monitoring ground deformation at Stromboli volcano was set up in the 1990s and later greatly improved during the effusive event of 2002–2003. Unlike other volcanoes, e.g. Mt. Etna, the magnitude of ground deformation signals of Stromboli is very small and through the entire period of operation of the monitoring system, only two major episodes of deformation, in 1994–1995 and 2000, which did not lead to an eruption but rather pure intrusion, were measured. Similarly to the 2002–2003 eruption, no important deformations were detected in the months before the 2007 eruption. However, unlike the 2002–2003 eruption, GPS and tilt stations recorded a continuous deflation during the entire 2007 eruption, which allowed us to infer a vertical elongated prolate ellipsoidal source, centered below the summit craters at depth of about 2.8 km b.s.l. Due to its geometry and position, this source simulates an elongated plumbing system connecting the deeper LP magma storage (depth from 5 to 10 km) with the HP shallower storage (0.8–3 km), both previously identified by petrologic and geochemical studies. This result represents the first contribution of geophysics to the definition of the plumbing system of Stromboli at intermediate depth. Finally, no deformation due to the plumbing system was measured for a long time after the end of the eruption. Meanwhile, the new terrestrial geodetic monitoring system installed within the Sciara del Fuoco, on the lava fan formed during the eruption, indicated that during the first months after the end of the eruption the ground velocity progressively decreased in time, suggesting that part of the deformation was due to the thermal contraction of the lava flow.
    Beschreibung: Published
    Beschreibung: 172-181
    Beschreibung: 1.3. TTC - Sorveglianza geodetica delle aree vulcaniche attive
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): Stromboli ; Ground Deformation ; source modelling ; flank instability ; 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::04.03. Geodesy::04.03.09. Instruments and techniques ; 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)
    Materialart: article
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  • 26
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    Unbekannt
    Deformation and eruptions at Mt. Etna (Italy): A lesson from 15 years of observations (2009)
    American Geophysical Union
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: 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.
    Beschreibung: 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.
    Beschreibung: Published
    Beschreibung: L02309
    Beschreibung: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Beschreibung: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Beschreibung: 1.10. TTC - Telerilevamento
    Beschreibung: 3.6. Fisica del vulcanismo
    Beschreibung: 4.3. TTC - Scenari di pericolosità vulcanica
    Beschreibung: 4.5. Degassamento naturale
    Beschreibung: JCR Journal
    Beschreibung: partially_open
    Schlagwort(e): 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)
    Materialart: article
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  • 27
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    Effects of soil gas permeability and recirculation flux on soil CO2 flux measurements performed using a closed dynamic accumulation chamber (2009)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: Dynamic accumulation chamber methods have been extensively used to estimate the total output of CO2 released from active volcanic area. In order to asses the performance and reliability of a closed dynamic system several tests were carried out with different soil permeabilities and soil CO2 fluxes. A special device was used to create a constant one-dimensional CO2 flux through a soil column with a known permeability. Three permeabilities were investigated, ranging between 3.6 × 10− 2 and 3.5 × 10 μm2, as were several CO2 fluxes (ranging between 1.1 × 10− 6 and 6.3 × 10− 5 kg m− 2 s− 1). The results highlight that the accuracy of soil CO2 flux measurements strictly depends on the soil gas permeability and the soil CO2 flux regimen. Generally chamber measurements underestimate CO2 fluxes at low soil permeability and low soil CO2 fluxes, whereas appreciable overestimations occur for high permeability soil, especially for high soil CO2 fluxes. Other tests carried out with different settings for the measurement device, such as the chamber volume and the flux of the pump used to recirculate air through the chamber and the gas analyzer (recirculation flux), revealed a strong dependence of the closed dynamic chamber measurements on the recirculation flux. Low recirculation fluxes (0.2–0.4 l min− 1) decreased the performance of the measurement system, causing underestimations of the actual soil CO2 flux, whereas higher values (0.6–1.0 l min− 1) resulted in overestimations, especially for elevated soil CO2 fluxes. An empirical equation was deduced to allow accumulation chamber fluxes to be calculated very accurately based on soil gas permeabilities measured in the field.
    Beschreibung: Published
    Beschreibung: 387-393
    Beschreibung: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Beschreibung: 4.5. Studi sul degassamento naturale e sui gas petroliferi
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): Soil CO2 flux measuraments ; Closed dynamic chamber ; soil gas permeability ; 04. Solid Earth::04.02. Exploration geophysics::04.02.01. Geochemical exploration ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. 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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  • 28
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    Unbekannt
    Low-frequency seismic signals recorded by OBS at Stromboli volcano (Southern Tyrrhenian Sea) (2009)
    AGU
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: Five three-component broadband ocean bottom seismometers (OBSs) were deployed on the seafloor around the Aeolian Islands (Southern Tyrrhenian Sea). By comparing OBSs digital seismograms, we found a low-frequency seismicity recorded only at OBS05, the nearest seafloor station to Stromboli volcano. This seismicity appears in the form of a continuous seismic signal (tremor-like-signal) as well as a considerable number of shock-like events. We focused on recordings from OBS05 to verify their correlation with Stromboli volcanic activity. From the spectral analysis, we observed low-frequency events (LP events), superposed upon the continuous background noise (tremor). LP events and tremor, showing similar energy fluctuations and frequency content, appear to be produced by the same dynamic processes. We interpret this low-frequency seismicity as probably originating from a continuous uprising of gas bubbles from the deeper part of the Stromboli magmatic column. This could highlight the existence of a deeper source for low-frequency seismicity.
    Beschreibung: Published
    Beschreibung: L04305
    Beschreibung: 3.6. Fisica del vulcanismo
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): Volcano-seismology ; low-frequency events ; tremor ; OBSs ; Stromboli (Southern Tyrrhenian Sea) ; 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
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 29
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    New geological insights and structural control on fluid circulation in La Fossa cone (Vulcano, Aeolian Islands, Italy) (2009)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: Electric resistivity tomography (ERT), self-potential (SP), soil CO2 flux, and temperature are used to study the inner structure of La Fossa cone (Vulcano, Aeolian Islands). Nine profiles were performed across the cone with a measurement spacing of 20 m. The crater rims of La Fossa cone are underlined by sharp horizontal resistivity contrasts. SP, CO2 flux, and temperature anomalies underline these boundaries which we interpret as structural limits associated to preferential circulation of fluids. The Pietre Cotte crater and Gran Cratere crater enclose the main hydrothermal system, identified at the centre of the edifice on the base of low electrical resistivity values (b20 Ω m) and strong CO2 degassing, SP, and temperature anomalies. In the periphery, the hydrothermal activity is also visible along structural boundaries such as the Punte Nere, Forgia Vecchia, and Palizzi crater rims and at the base of the cone, on the southern side of the edifice, along a fault attributed to the NW main tectonic trend of the island. Inside the Punte Nere crater, the ERT sections show an electrical resistive body that we interpret as an intrusion or a dome. This magmatic body is reconstructed in 3D using the available ERT profiles. Its shape and position, with respect to the Pietre Cotte crater fault, allows replacing this structure in the chronology of the development of the volcano. It corresponds to a late phase of activity of the Punte Nere edifice. Considering the position of the SP, soil CO2 flux, and temperature maxima and the repartition of conductive zones related to hydrothermal circulation with respect to the main structural features, La Fossa cone could be considered as a relevant example of the strong influence of preexisting structures on hydrothermal fluid circulation at the scale of a volcanic edifice.
    Beschreibung: Published
    Beschreibung: 231-245
    Beschreibung: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Beschreibung: JCR Journal
    Beschreibung: partially_open
    Schlagwort(e): electrical resistivity ; self-potential ; soil CO2 degassing ; temperature ; fluid circulation ; hydrothermal system ; structural boundary ; Vulcano ; La Fossa cone ; 03. Hydrosphere::03.02. Hydrology::03.02.04. Measurements and monitoring ; 03. Hydrosphere::03.03. Physical::03.03.02. General circulation ; 04. Solid Earth::04.01. Earth Interior::04.01.01. Composition and state ; 04. Solid Earth::04.02. Exploration geophysics::04.02.07. Instruments and techniques ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 30
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    Unbekannt
    Nitrogen Isotopes in Volcanic Fluids of Different Geodynamic Settings (2009)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: Nitrogen isotopes , N2/36Ar and 3He/4He were measured in volcanic fluids within different geodynamic settings. Subduction zones are represented by Aeolian archipelago, Mexican volcanic belt and Hellenic arc, spreading zones – by Socorro island in Mexico and Iceland and hot spots by Iceland and Islands of Cabo Verde. The δ15N values, corrected for air contamination of volcanic fluids, discharged from Vulcano Island (Italy), highlighted the presence of heavy nitrogen (around +4.3 ±0.5‰). Similar 15N values (around +5‰), have been measured for the fluids collected in the Jalisco Block, that is a geologically and tectonically complex forearc zone of the northwestern Mexico [1]. Positive values (15N around +3‰) have been also measured in the volcanic fluids discharged from Nysiros island located in the Ellenic Arc characterized by subduction processes. All uncorrected data for the Socorro island are in the range of -1 to -2‰. The results of raw nitrogen isotope data of Iceland samples reveal more negative isotope composition (about -4.4‰). On the basis of the non-atmospheric N2 fraction (around 50%) the corrected data of 15N for Iceland are around -16‰, very close to the values proposed by [2]. In a volcanic gas sample from Fogo volcano (Cabo Verde islands) we found a very negative value: -9.9‰ and -15‰ for raw and corrected values, respectively.
    Beschreibung: Geochimica et Cosmochimica Acta
    Beschreibung: Published
    Beschreibung: Davos, Switzerland
    Beschreibung: 2.4. TTC - Laboratori di geochimica dei fluidi
    Beschreibung: open
    Schlagwort(e): Nitrogen Isotopes ; Helium Isotopes ; Volcanic fluids ; 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::04.08.01. Gases ; 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)
    Materialart: Poster session
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  • 31
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    Experimental solidification of anhydrous latitic and trachytic melts at different cooling rates: the role of nucleation kinetics (2008)
    Elsevier
    Details
    Publikationsdatum: 2020-10-29
    Beschreibung: Two sets of cooling experiments were run at atmospheric conditions for two anhydrous starting latitic and trachytic melts: 1) five cooling rates (25, 12.5, 3, 0.5, and 0.125 °C/min) between 1300° and 800 °C, and 2) a 11 0.5 °C/min cooling rate from 1300 °C with quench temperatures at 1200°, 1100°, 1000° and 900 °C. Trachytic run-products are invariably glassy. Nucleation is also suppressed in the latitic run-products at the three highest 13 cooling rates. Conversely, in the 0.5 and 0.125 °C/min runs, latites have a crystal content of 90 vol.%. The 14 phases are: plagioclase, clinopyroxene, glass and iron-bearing oxide (in order of abundance). The variable 15 quench temperatures, investigated by coupling experiments with Pt-wire and Pt- capsule sample containers inset 2,again did not produce crystallization of trachyte, whereas latitic samples are characterized by 10 vol.% of oxides, pyroxenes and plagioclase (in order of appearance), at temperature b1000 °C. Effects of (preferential) heterogeneous nucleation on sample holders, of superheating degree, and chemical species loss during cooling are absent for both melt compositions. The difference of solidification paths between these two silicate melts can be ascribed only to their small chemical differences. In comparison with calculated equilibrium conditions all the experimental latitic and trachytic run-products revealed strong kinetic effects, interpretable in the light of the nucleation theory. The glass- forming ability (GFA) of trachyte is higher, whereas their critical cooling rate (Rc) is lower (b0.125 °C/min), in comparison to latitic melts (RcN0.5 °C/min). The experimental results carried out in this study can be applied to lava flows and domes; trachytic lavas are able to flow for longer period with respect to latitic ones in a metastable condition. Glass-rich terrestrial lavas, i.e. obsidians, can be the result of sluggish nucleation kinetics due to the relative high polymerisation of evolved silicate melts.
    Beschreibung: Published
    Beschreibung: 91-101
    Beschreibung: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Beschreibung: 3.6. Fisica del vulcanismo
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): crystallization ; lava flows ; 04. Solid Earth::04.08. Volcanology::04.08.02. Experimental volcanism ; 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::04.08.07. Instruments and techniques ; 05. General::05.02. Data dissemination::05.02.02. Seismological data
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 32
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    Unbekannt
    Carbon Dioxide degassing at Latera caldera (Italy): evidence of geothermal reservoir and evaluation of its potential energy (2008)
    AGU
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: In order to test the potentiality of soil CO2 diffuse degassing measurements for the study of underground mass and heat transfer in geothermal systems detailed surveys were performed at Latera Caldera which is an excellent test site, due to the abundant available subsurface data. Over 2500 measurements of soil CO2 flux revealed that endogenous CO2 at Latera Caldera concentrates on a NE-SW band coinciding with a structural high of fractured Mesozoic limestones hosting a water-dominated high-enthalpy geothermal reservoir. The total hydrothermal CO2 degassing from the structural high has been evaluated at 350 t d-1 from an area of 3.1 km2. It has been estimated that such a CO2 release would imply a geothermal liquid flux of 263 kg s-1, with a heat release of 239 MW. The chemical and isotopic composition of the gas indicates a provenance from the geothermal reservoir and that CO2 is partly originated by thermal metamorphic decarbonation in the hottest deepest parts of the system and partly has a likely mantle origin. The ratios of CO2, H2, CH2 and CO to Ar, were used to estimate the T-P conditions of the reservoir. Results cluster at T ~ 200-300°C and PCO2 ~ 100-200 bars, close to the actual well measurements. Finally the approach proved to be an excellent tool to investigate the presence of an active geothermal reservoir at depth and that the H2-CO2-CH4-CO-Ar gas composition is a useful T-P geochemical indicator for such CO2 rich geothermal systems.
    Beschreibung: Published
    Beschreibung: B12204
    Beschreibung: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Beschreibung: 2.4. TTC - Laboratori di geochimica dei fluidi
    Beschreibung: 4.5. Degassamento naturale
    Beschreibung: JCR Journal
    Beschreibung: partially_open
    Schlagwort(e): Carbon Dioxide degassing ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 33
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    Unbekannt
    Thermal monitoring of hydrothermal activity by permanent infrared automatic stations: Results obtained at Solfatara di Pozzuoli, Campi Flegrei (Italy) (2008)
    AGU
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: A permanent automatic infrared (IR) station was installed at Solfatara crater, the most active zone of Campi Flegrei caldera. After a positive in situ calibration of the IR camera, we analyze 2175 thermal IR images of the same scene from 2004 to 2007. The scene includes a portion of the steam heated hot soils of Solfatara. The experiment was initiated to detect and quantify temperature changes of the shallow thermal structure of a quiescent volcano such as Solfatara over long periods. Ambient temperature results as the main parameter affecting IR temperatures while air humidity and rain control image quality. A geometric correction of the images was necessary to remove the effects of slow movement of the camera. After a suitable correction the images give a reliable and detailed picture of the temperature changes, over the period October 2004 – January 2007, which suggests origin of the changes were linked to anthropogenic activity, vegetation growth and to the increase of the flux of hydrothermal fluids in the area of the hottest fumaroles. Two positive temperature anomalies were registered after the occurrence of two seismic swarms which affected the hydrothermal system of Solfatara in October 2005 and October 2006. It is worth noting that these signs were detected in a system characterized by a low level of activity with respect to systems affected by real volcanic crisis where more spectacular results will be expected. Results of the experiment show that this kind of monitoring system can be a suitable tool for volcanic surveillance.
    Beschreibung: Published
    Beschreibung: B12206
    Beschreibung: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Beschreibung: 4.5. Degassamento naturale
    Beschreibung: JCR Journal
    Beschreibung: partially_open
    Schlagwort(e): Termal Monitoring of Hydrothermal ; Activity ; 03. Hydrosphere::03.04. Chemical and biological::03.04.06. Hydrothermal systems ; 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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  • 34
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    Unbekannt
    Volumetric observations during paroxysmal eruptions at Mount Etna: pressurized drainage of a shallow chamber or pulsed supply? (2008)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: The October 17 to November 5, 1999, eruption of Mount Etna’s Bocca Nuova crater emplaced a V15U106 m3 flow field. The eruption was characterized by 11 paroxysmal events during which intense Strombolian and lava fountain activity fed vigorous channelized PaPa flows at eruption rates of up to 120 m3 s31. Each paroxysm lasted between 75 and 450 min, and was separated by periods of less intense Strombolian activity and less vigorous (610 m3 s31) effusion. Ground-based, satellite- and model-derived volumetric data show that the eruption was characterized by two periods during which eruption rates and cumulative volume showed exponential decay. This is consistent with a scenario whereby the system was depressurized during the first eruptive period (October 17^23), repressurized during an October 24 pause, and then depressurized again during the second period (October 25^28). The imbalance between the erupted and supplied volumes mean that the two periods involved the collection of 1.5^5.7U106 m3 and 1.2^ 3.6U106 m3, respectively, or an increase in the time-averaged supply to 11.6^13.6 m3 s31 and 12.5^14.9 m3 s31. Two models are consistent with the observed episodic fountaining, derived volumetric trends and calculated volume imbalance: a magma collection model and a pulsed supply model. In the former case, depressurization of a shallow reservoir cause the observed volumetric trends and foam collapse at the reservoir roof powers fountaining. In the pulsing case, variations in magma flux account for pressurization^depressurization and supply the excess volume. Increases in rise rate and volatile flux, coupled with rapid exsolution during ascent, trigger fountaining. Limiting equations that define critical foam layer volumes and magma rise rates necessary for Hawaiian-style fountaining favor the latter model.
    Beschreibung: Published
    Beschreibung: 79-95
    Beschreibung: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Beschreibung: 3.5. Geologia e storia dei sistemi vulcanici
    Beschreibung: 3.6. Fisica del vulcanismo
    Beschreibung: 4.3. TTC - Scenari di pericolosità vulcanica
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): Etna ; lava fountaining ; eruption rates ; lava channel ; foam layers ; rise rates ; 04. Solid Earth::04.01. Earth Interior::04.01.99. General or miscellaneous ; 04. Solid Earth::04.01. Earth Interior::04.01.05. Rheology ; 04. Solid Earth::04.02. Exploration geophysics::04.02.99. General or miscellaneous ; 04. Solid Earth::04.02. Exploration geophysics::04.02.05. Downhole, radioactivity, remote sensing, and other methods ; 04. Solid Earth::04.02. Exploration geophysics::04.02.07. Instruments and techniques ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.11. Instruments and techniques ; 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::04.08.02. Experimental volcanism ; 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::04.08.05. Volcanic rocks ; 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)
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  • 35
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    Unbekannt
    Intrusion of eccentric dikes: The case of the 2001 eruption and its role in the dynamics of Mt. Etna volcano (2008)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: The 2001 eruption represents one of the most studied events both from volcanological and geophysical point of view on Mt. Etna. This eruption was a crucial event in the recent dynamic of the volcano, marking the passage from a period (March 1993 – June 2001) of moderate stability with slow, continuous flank sliding and contemporaneous summit eruptions, to a period (July 2001 to present) of dramatically increased flank deformations and flank eruptions. We show new GPS data and high precision relocation of seismicity in order to demonstrate the role of the 2001 intrusive phase in this change of the dynamic regime of the volcano. GPS data consist of two kinematic surveys carried out on 12 July, a few hours before the beginning of the seismic swarm, and on 17 July, just after the onset of eruptive activity. A picture of the spatial distribution of the sin-eruptive seismicity has been obtained using the HypoDD relocation algorithm based on the double-difference (DD) technique. Modeling of GPS measurements reveal a southward motion of the upper southern part of the volcano, driven by a NNW-SSE structure showing mainly left-lateral kinematics. Precise hypocenter location evidences an aseismic zone at about sea level, where the magma upraise was characterized by a much higher velocity and an abrupt westward shift, revealing the existence of a weakened or ductile zone. These results reveal how an intrusion of a dike can severely modify the shallow stress field, triggering significant flank failure. In 2001, the intrusion was driven by a weakened surface, which might correspond to a decollement plane of the portion of the volcano affected by flank instability, inducing an additional stress testified by GPS measurements and seismic data, which led to an acceleration of the sliding flanks.
    Beschreibung: In press
    Beschreibung: 1.1. TTC - Monitoraggio sismico del territorio nazionale
    Beschreibung: 1.3. TTC - Sorveglianza geodetica delle aree vulcaniche attive
    Beschreibung: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Beschreibung: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Beschreibung: 3.2. Tettonica attiva
    Beschreibung: 3.5. Geologia e storia dei sistemi vulcanici
    Beschreibung: 3.6. Fisica del vulcanismo
    Beschreibung: 4.2. TTC - Scenari e mappe di pericolosità sismica
    Beschreibung: 4.3. TTC - Scenari di pericolosità vulcanica
    Beschreibung: 4.4. Scenari e mitigazione del rischio ambientale
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): Stress release ; Dike ; Volcano-tectonics ; Flank instability ; Mount Etna ; Instrumental monitoring ; 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::04.03. 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::04.04.01. Earthquake geology and paleoseismology ; 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::04.06.03. Earthquake source and dynamics ; 04. Solid Earth::04.06. Seismology::04.06.04. Ground motion ; 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::04.07. 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::04.08.06. 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)
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  • 36
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    Unbekannt
    Comparison between different methodologies for detecting Radon in soil along an active fault: the case of the Pernicana fault system, Mt. Etna (Italy) (2008)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: Three different methodologies were used to measure Radon (222Rn) in soil, based on both passive and active detection system. The first technique consisted of Solid State Nuclear Track Detectors (SSNTD), CR-39 type, and allowed integrated measurements. The second one consisted of a portable device for short time measurements. The last consisted of a continuous measurement device for extended monitoring, placed in selected sites. Soil 222Rn activity was measured together with soil Thoron (220Rn) and soil carbon dioxide (CO2) efflux, and it was compared with the content of radionuclides in the rocks. Two different soil gas horizontal transects were investigated across the Pernicana fault system (NE flank of Mount Etna), from November 2006 to April 2007. The results obtained with the three methodologies are in a general agreement with each other and reflect the tectonic settings of the investigated study area. The lowest 222Rn values were recorded just on the fault plane, and relatively higher values were recorded a few tens of meters from the fault axis on both of its sides. This pattern could be explained as a dilution effect resulting from high rates of soil CO2 efflux. Time variations of 222Rn activity were mostly linked to atmospheric influences, whereas no significant correlation with the volcanic activity was observed. In order to further investigate regional radon distributions, spot measurements were made to identify sites having high Rn emissions that could subsequently be monitored for temporal radon variations.. SSNTD measurements allow for extended-duration monitoring of a relatively large number of sites, although with some loss of temporal resolution due to their long integration time. Continuous monitoring probes are optimal for detailed time monitoring, but because of their expense, they can best be used to complement the information acquired with SSNTD in a network of monitored sites.
    Beschreibung: In press
    Beschreibung: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Beschreibung: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Beschreibung: 3.2. Tettonica attiva
    Beschreibung: 4.4. Scenari e mitigazione del rischio ambientale
    Beschreibung: 4.5. Degassamento naturale
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): Soil Radon and Thoron activity ; soil CO2 efflux ; Pernicana fault system ; Mount Etna ; volcano-tectonic monitoring ; 03. Hydrosphere::03.04. Chemical and biological::03.04.07. Radioactivity and isotopes ; 03. Hydrosphere::03.04. Chemical and biological::03.04.08. Instruments and techniques ; 04. Solid Earth::04.01. Earth Interior::04.01.99. General or miscellaneous ; 04. Solid Earth::04.02. Exploration geophysics::04.02.01. Geochemical exploration ; 04. Solid Earth::04.02. Exploration geophysics::04.02.05. Downhole, radioactivity, remote sensing, and other methods ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.06. Rheology, friction, and structure of fault zones ; 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::04.07. Tectonophysics::04.07.99. General or miscellaneous ; 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::04.08.06. 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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  • 37
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    Inner structure of La Fossa di Vulcano (Vulcano Island, southern Tyrrhenian Sea, Italy) revealed by high-resolution electric resistivity tomography coupled with self-potential, temperature, and CO2 diffuse degassing measurements (2008)
    AGU
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: La Fossa cone is an active stratovolcano located on Vulcano Island in the Aeolian Archipelago (southern Italy). Its activity is characterized by explosive phreatic and phreatomagmatic eruptions producing wet and dry pyroclastic surges, pumice fall deposits, and highly viscous lava flows. Nine 2-D electrical resistivity tomograms (ERTs; electrode spacing 20 m, with a depth of investigation 〉200 m) were obtained to image the edifice. In addition, we also measured the self-potential, the CO2 flux from the soil, and the temperature along these profiles at the same locations. These data provide complementary information to interpret the ERT profiles. The ERT profiles allow us to identify the main structural boundaries (and their associated fluid circulations) defining the shallow architecture of the Fossa cone. The hydrothermal system is identified by very low values of the electrical resistivity (〈20 W m). Its lateral extension is clearly limited by the crater boundaries, which are relatively resistive (〉400Wm). Inside the crater it is possible to follow the plumbing system of the main fumarolic areas. On the flank of the edifice a thick layer of tuff is also marked by very low resistivity values (in the range 1–20 W m) because of its composition in clays and zeolites. The ashes and pyroclastic materials ejected during the nineteenth-century eruptions and partially covering the flank of the volcano correspond to relatively resistive materials (several hundreds to several thousands W m). We carried out laboratory measurements of the electrical resistivity and the streaming potential coupling coefficient of the main materials forming the volcanic edifice. A 2-D simulation of the groundwater flow is performed over the edifice using a commercial finite element code. Input parameters are the topography, the ERT cross section, and the value of the measured streaming current coupling coefficient. From this simulation we computed the self-potential field, and we found good agreement with the measured self-potential data by adjusting the boundary conditions for the flux of water. Inverse modeling shows that self-potential data can be used to determine the pattern of groundwater flow and potentially to assess water budget at the scale of the volcanic edifice.
    Beschreibung: Published
    Beschreibung: B07207
    Beschreibung: 4.3. TTC - Scenari di pericolosità vulcanica
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): Vulcano ; high-resolution electric resistivity ; self-potential ; CO2 diffuse degassing ; 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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  • 38
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    Accumulation chamber measurements of methane fluxes from natural environments and landfills (2008)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: Direct measurement of present day CH4 diffuse degassing from the soil represents an effective tool to better estimate the degassing rate of individual sources and to calibrate global Earth degassing estimates. While many data exist on CH4 emissions from ecosystems, agricultural soils and landfills, few estimates of CH4 emissions from volcanic-geothermal areas have been performed. The authors report results and discuss applications of accumulation-chamber measurements of soil CH4 and CO2 flux from Solfatara of Pozzuoli (Naples), Vulcano Island and Poggio dell’Olivo (Viterbo) volcanic-geothermal areas, and the Palma Campania landfill (Naples). Volcanic-geothermal study areas are characterised by vent discharges of fluids with different CH4/CO2 ratios (from 4.7X1E-5 to 7.5X1E-5, 4.7X1E-4 and 2.5X1E-3 by weight, for Solfatara of Pozzuoli, Vulcano island, and Poggio dell’Olivo areas, respectively). Soil CH4 fluxes range from 0.003 to 48 g m-2 day-1 in the volcanic-geothermal areas and from 0.0021 to 936 g m-2 day-1 in the landfill, with high spatial variability observed in all areas. Using statistical methods different flux populations were distinguished (i.e. background soil gases and deeply derived gases) and the total gas emissions from study sites calculated. The results of this work show that CH4/CO2 ratios of deep fluids, fumarolic fluids in the case of the volcanicgeothermal environment and biogas in landfills, are roughly maintained in the gas phase diffusely degassed by the soil. Due to high spatial variability, a large number of flux measurements and appropriate statistical methods are needed to estimate total gas discharge from study areas. Furthermore, the simultaneous measurement of diffuse CH4 and CO2 fluxes represents a strong constraint for interpretative models of deep processes associated with soil degassing.
    Beschreibung: Published
    Beschreibung: 45-54
    Beschreibung: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): methane flux ; accumulation chamber ; 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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  • 39
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    Sliding episodes during the 2002–2003 Stromboli lava effusion: Insights from seismic, volcanic, and statistical data analysis (2008)
    American Geophysical Union
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: 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.
    Beschreibung: This work was supported financially by Istituto Nazionale di Geofisica e Vulcanologia and Dipartimento per la Protezione Civile, project INGV-DPC V4/02.
    Beschreibung: Published
    Beschreibung: Q04022
    Beschreibung: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Beschreibung: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Beschreibung: 3.6. Fisica del vulcanismo
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): 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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  • 40
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    Unbekannt
    Unmanned aerial vehicle measurements of volcanic carbon dioxide fluxes (2008)
    American Geophysical Union
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: 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.
    Beschreibung: Published
    Beschreibung: L06303
    Beschreibung: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): 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
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  • 41
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    Mercury and halogen emissions from Masaya and Telica volcanoes, Nicaragua (2008)
    AGU
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: We report measurements of Hg, SO2, and halogens (HCl, HBr, HI) in volcanic gases from Masaya volcano, Nicaragua, and gaseous SO2 and halogens from Telica volcano, Nicaragua. Mercury measurements were made with a Lumex 915+ portable mercury vapor analyzer and gold traps, while halogens, CO2 and S species were monitored with a portable multi gas sensor and filter packs. Lumex Hg concentrations in the plume were consistently above background and ranged up to 350 ng/m3. Hg/SO2 mass ratios measured with the real-time instruments ranged from 1.1*10-7 to 3.5*10-5 (mean 2*10-5). Total gaseous mercury TGM)concentrations measured by gold trap ranged from 100 to 225 ng/m3. Reactive gaseous mercury accounted for 1% of TGM, while particulate mercury was 5% of the TGM. Field measurements of Masaya’s SO2 flux, combined with the Hg/SO2 ratio, indicate a Hg flux from Masaya of 7.2 Mg/a-1. At Masaya’s low temperature fumaroles, Hg/CO2 mass ratios were consistently around 2*10-8, lower than observed in the main vent (Hg/CO2 10-7). Low-temperature fumarole Hg fluxes from Masaya are insignificant (150 g a-1). Ratios of S, C and halogen species were also measured at Masaya and Telica volcanoes. CO2/SO2 ratios at Masaya ranged from 2.8 to 3.9, comparable to previously published values. At Masaya molar Br/SO2 was 3*10-4 and I/SO2 was 2*10-5, suggesting fluxes of 0.2–0.5 Mg HBr d-1 and 0.02–0.05 Mg HI d-1. At Telica the Br/SO2 ratio was also 3*10-4 and the I/SO2 ratio was 5.8*10-5, with corresponding fluxes of 0.2 Mg HBr d-1 and 0.06 Mg HI d-1. Gases at both volcanoes are enriched in I relative to Br and Cl, compared to gases from volcanoes elsewhere.
    Beschreibung: This work was funded by NERC grant NE/ C511180/1/.
    Beschreibung: Published
    Beschreibung: B06203
    Beschreibung: 4.5. Degassamento naturale
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): Mercury ; Halogen ; Volcanic emissions ; Masaya volcano ; Telica volcano ; 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
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  • 42
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    Paleo-environmental and volcano-tectonic evolution of the southeastern £ank of Mt. Etna during the last 225 ka inferred from the volcanic succession of the ‘Timpe’, Acireale, Sicily (2008)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: The tectonic escarpments locally known as ‘Timpe’ cut a large sector of the eastern flank of Etna, and allow an ancient volcanic succession dating back to 225 ka to be exposed. Geological and volcanological investigations carried out on this succession have allowed us to recognize relevant angular unconformities and volcanic features which are the remnants of eruptive fissures, as well as important changes in the nature, composition and magmatic affinity of the exposed volcanics. In particular, the recognition in the lower part of the succession of important and unequivocal evidence of ancient eruptive fissures led us to propose a local origin for these volcanics and to revise previous interpretations which attributed their westward-dipping to the progressive tectonic tilting of strata. These elements led us to reinterpret the main features of the volcanic activity occurring since 250 ka BP and their relationship with tectonic structures active in the eastern flank of Etna. We propose a complex paleo-environmental and volcanotectonic evolution of the southeastern flank of Mt. Etna, in which the Timpe fault system played the role of the crustal structure that allowed the rise and eruption of magmas in the above considered time span.
    Beschreibung: Published
    Beschreibung: 289-306
    Beschreibung: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Beschreibung: 3.5. Geologia e storia dei sistemi vulcanici
    Beschreibung: 3.6. Fisica del vulcanismo
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): Mount Etna ; tectonics ; fisssure eruptions ; columnar basalt ; fault escarpment ; xenoliths ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.03. Geomorphology ; 04. Solid Earth::04.04. Geology::04.04.05. Mineralogy and petrology ; 04. Solid Earth::04.04. Geology::04.04.06. Rheology, friction, and structure of fault zones ; 04. Solid Earth::04.04. Geology::04.04.07. Rock geochemistry ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.04. Geology::04.04.10. Stratigraphy ; 04. Solid Earth::04.04. Geology::04.04.11. Instruments and techniques ; 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::04.07.04. Plate boundaries, motion, and tectonics ; 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::04.08.01. 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::04.08.07. 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
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  • 43
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    On the fractal dimension of the fallout deposits: A case study of the 79 A.D. Plinian eruption at Mt. Vesuvius (2008)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: We investigated the existence of a fractal law (power law) distribution of size pyroclastic fragments erupted during the fallout phase of the 79 A.D. Plinian eruption at Mt. Vesuvius. In particular, we performed a particle size distribution analysis on 18 white and grey pumice samples collected in six sites distributed in the SW sector of Mt. Vesuvius. Our measurements show that the fragmentation of samples in the investigated range (from 32 mm to 850 μm) follows a power law, guaranteeing the scale invariance of the process. The relationship frequency-size distribution of the fragments is verified independently from the nature (i.e., pumices and lithics) and stratigraphic height of the considered samples in the pyroclastic deposit. Therefore, the fractal fragmentation theory can be indicated for evaluating the relationship between the intensity of fragmentation (fractal dimension D) and eruption energy. In this way the apparent chaotic distribution of the particles in the fallout deposits hides a self-organized complexity revealed by the retrieved power law distribution. We further remark that a key aspect of our analysis is the founded evidence that the fractal dimension of the lithics is systematically greater than that of the pumices.
    Beschreibung: Published
    Beschreibung: 288–299
    Beschreibung: 3.6. Fisica del vulcanismo
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): fragmentation ; power law distribution ; fractal dimension ; scale invariant ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
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  • 44
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    Scanning tomography of SO2 distribution in a volcanic gas plume (2008)
    American Geophysical Union
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: 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.
    Beschreibung: Published
    Beschreibung: L17811
    Beschreibung: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): 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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  • 45
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    An advanced video-based system for monitoring active volcanoes (2007)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: Video surveillance systems are consolidated techniques for monitoring eruptive phenomena in volcanic areas. Along with these systems, which use standard video cameras, people working in this field sometimes make use of infrared cameras providing useful information about the thermal evolution of eruptions. Real-time analysis of the acquired frames is required, along with image storing, to analyze and classify the activity of volcanoes. Human effort and large storing capabilities are hence required to perform monitoring tasks. In this paper we present a new strategy aimed at improving the performance of video surveillance systems in terms of human-independent image processing and storing optimization. The proposed methodology is based on real-time thermo-graphic analysis of the area considered. The analysis is performed by processing images acquired with an IR camera and extracting information about meaningful volcanic events. Two software tools were developed. The first provides information about the activity being monitored and automatically adapts the image storing rate. The second tool automatically produces useful information about the eruptive activity encompassed by a selected frame sequence. The software developed includes a suitable user interface allowing for convenient management of the acquired images and easy access to information about the volcanic activity monitored.
    Beschreibung: Published
    Beschreibung: 85-91
    Beschreibung: reserved
    Schlagwort(e): Volcano monitoring ; Image processing ; Smart storing rate ; Eruption data ; 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
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  • 46
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    Effects of a volcanic plume on thermal imaging data (2007)
    AGU
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: Ground-based thermal imaging is becoming an increasingly important tool for volcano surveillance, however the impact of volcanic plumes on quantitative measurements of surface temperature has not been previously evaluated. Here we use a radiative transfer model to simulate gas (primarily H2O and SO2) and aerosol absorptions over the path between a thermal camera and a heat source on Stromboli volcano, Italy. A FTIR spectrometer was used to quantify path amounts of gases likely to be encountered when making thermal measurements of the active craters. We find that when using a camera sensitive from 7.5 to 13 mm, underestimates of 400 K may be produced when viewing a source with an actual temperature of 1200 K. Cameras that operate between 3 and 5 mm are somewhat less susceptible to these errors.
    Beschreibung: Published
    Beschreibung: L14311
    Beschreibung: reserved
    Schlagwort(e): NONE ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
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  • 47
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    Contemporary total dissolved gas pressure and soil temperature anomalies recorded at Stromboli volcano (Italy) (2007)
    American Geophysical Union
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: 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.
    Beschreibung: Published
    Beschreibung: L08301
    Beschreibung: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): 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
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  • 48
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    Continuous soil radon monitoring during the July 2006 Etna eruption (2007)
    AGU
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: Continuous soil radon monitoring was carried out near the Southeast Crater (SEC) of Mt. Etna during the 10-day July 2006 Strombolian-effusive eruption. This signal was compared with simultaneously acquired volcanic tremor and thermal radiance data. The onset of explosive activity and a lava fountaining episode were preceded by some hours with increases in radon soil emission by 4–5 orders of magnitude, which we interpret as precursors. Minor changes in eruptive behavior did not produce significant variations in the monitored parameters. The remarkably high radon concentrations we observed are unprecedented in the literature. We interpret peaks in radon activity as due primarily to microfracturing of uranium-bearing rock. These observations suggest that radon measurements in the summit area of Etna are strongly controlled by the state of stress within the volcano and demonstrate the usefulness of radon data acquisition before and during eruptions.
    Beschreibung: Published
    Beschreibung: L24316
    Beschreibung: reserved
    Schlagwort(e): NONE ; 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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  • 49
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    The SO2 camera: A simple, fast and cheap method for ground-based imaging of SO2 in volcanic plumes (2007)
    AGU
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: SO2 flux is widely monitored on active volcanoes as it gives a window into the hidden, subsurface magma dynamics. We present here a new approach to SO2 flux monitoring using ultraviolet imaging of the volcanic plume through carefully chosen filters to produce images of SO2 column amount. The SO2 camera heralds a breakthrough in both our ability to measure SO2 flux at unprecedented frequencies (2 Hz) and at unprecedented accuracy, thanks to the application of correlation techniques to determine wind speed directly from the images and the ability to measure the whole profile simultaneously. In this paper we detail the commercially available pieces required to construct the SO2 camera, introduce a retrieval scheme to determine SO2 amounts from the images and present results from a field campaign in November 2005 on Sakurajima volcano, Japan.
    Beschreibung: Published
    Beschreibung: L24804
    Beschreibung: reserved
    Schlagwort(e): NONE ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
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  • 50
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    Dynamics of the eastern flank of Mt. Etna volcano (Italy) investigated by a dense GPS network (2007)
    Elsevier
    Details
    Publikationsdatum: 2017-04-03
    Beschreibung: Mount Etna has developed at the intersection of two regional tectonic lineaments, the NNW–SSE trending Hybleo–Maltese escarpment, which separates the thick inland continental crust of the African platform from the Ionian Mesozoic oceanic crust, and the NE–SW Messina–Fiumefreddo fault that marks a rift zone between south Calabria and north-eastern Sicily, extending as far as the Mt. Etna area. All tectonic features affect, with outstanding surface features, the eastern side of the volcano. The eastern flank of the volcano is affected by a long-term motion toward ESE. In 1997, in order to increase the detail of the ground deformation pattern on the lower eastern flank of Mt. Etna, a new GPS network, the “Ionica” network, was installed on this sector of the volcano. This GPS network consists of 24 stations and covers the lower eastern flank of the volcano from the town of Catania to Taormina and from the coastline up to an altitude of about 1300 m. All the new stations consist in self-centring benchmarks; this kind of benchmark allows all station set-up errors to be avoided. Before the merging of the Ionica network to the frame of the global GPS network of Mt. Etna (in June 2001), three surveys were carried out on this network: in September 1997, August 1998 and January 2001. From the ground deformation pattern, it is possible to distinguish two different sectors, showing different characteristics of deformation. The southern part of the network shows a more uniform distribution of the vertical motion with a mean SE-ward horizontal component while the northern one shows an heterogeneous vertical motion with a ESE-ward horizontal component. Furthermore, a higher velocity is detected between 1997 and 1998, due to the additional stress induced by a shallow intrusion on the NW flank of the volcano. The model resulting from data inversions defines a wide sliding plane beneath the entire eastern flank of the volcano with a low dip angle. The expected velocity vectors fit well the observed ones, even if the measured velocities are still quite higher than expected, at lowermost stations. The vertical inclination of the velocity vectors measured during the 1998–2001 period, gradually decreases from West to East suggesting a sort of rotational movement of the south-eastern flank, interrupted by some anomalous vectors on the lower part, that show higher vertical velocities. These anomalies, being located on a wedge defined by the intersection of the main NNW–SSE and NE–SW fault systems and near the Timpe faults, are probably due to the activity of the vertical faults cutting the lower eastern flank of Mt. Etna. Stations lying on the hanging wall and on the footwall of the Timpe fault system are affected by similar horizontal displacements, meaning that these structures are moving eastwards together with the sliding flank; this evidence suggests that the Timpe faults are probably second order structures, with respect to the detachment surface. These results depict a structural framework of the eastern flank of Mt. Etna in which the low angle dislocation can be considered as a first order approximation of an actual listric plane and the current active part of the Timpe fault system is confined above the detachment surface.
    Beschreibung: Published
    Beschreibung: 357-369
    Beschreibung: reserved
    Schlagwort(e): ground deformation ; flank dynamics ; volcano–tectonics ; Etna volcano ; 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::04.08. Volcanology::04.08.07. Instruments and techniques
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  • 51
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    Composite ground deformation pattern forerunning the 2004–2005 Mount Etna eruption (2007)
    AGU
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: After the end of the 2002–2003 eruption, Mount Etna activity was characterized only by gentle degassing at the summit craters and some earthquake swarms. Suddenly, an eruption started on 7 September 2004 in complete absence of summit crater volcanic activity, seismicity or seismic tremor, and ground deformation. This is the first time that magma poured out passively without preeruptive and coeruptive volcanic and/or geophysical phenomena. The primary key to understanding this event is represented by the ground deformation pattern recorded through GPS measurements during the year before the eruption. The ground deformation shows inflation superimposed by a predominant eastward movement of the eastern sector at a rate never observed before in a noneruptive period. The images from satellite radar interferometry confirmed this pattern. The deformation field clearly shows that the maximum tension in the eastern sector of the volcano caused the opening of the eruptive fracture which favored the silent pouring out of already resident magma.
    Beschreibung: Published
    Beschreibung: B12207
    Beschreibung: reserved
    Schlagwort(e): NONE ; 04. Solid Earth::04.03. Geodesy::04.03.07. Satellite geodesy ; 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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  • 52
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    Lava flow identification and aging by means of lidar intensity: Mount Etna case (2007)
    American Geophysical Union
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: An application of light detection and ranging (lidar) intensity for the identification and mapping of different lava flows from the Mount Etna (Italy) active volcano is described. In September 2004 an airborne lidar survey was flown over summit sectors of Mount Etna. The information derived from lidar intensity values was used to compare the lava flows with respect to their age of emplacement. Analyzed lava flows vary in age between those dating prior to A.D. 1610 and those active during the survey (2004–2005 eruptions). The target-emitter distance, as well as surface roughness and texture at the lidar footprint scale, is the main parameter controlling the intensity response of lava flows. Variations in the roughness and texture of surfaces at a meter scale result from two main processes, initial lava cooling and subsequent surface weathering; both lead to variations in the original surface roughness of the flow. In summary: (1) initially, from the time of emplacement, the lidar intensity of lava flow surfaces decreases and (2) about 6 years after emplacement the lidar intensity of lava surfaces starts to increase with the age of flows. Lidar capability in terms of geometric (accuracy of ∼1 m in plan position and less than 1 m in elevation) and spectral (lidar intensity depends on surface reflection at λ = 1.064 μm) information can thus be effectively used to map lava flows and to define a relative chronology of lava emplacement.
    Beschreibung: Published
    Beschreibung: B02201
    Beschreibung: 3.6. Fisica del vulcanismo
    Beschreibung: 3.5. Geologia e storia dei sistemi vulcanici
    Beschreibung: JCR Journal
    Beschreibung: reserved
    Schlagwort(e): lava flows ; mapping ; lidar ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
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  • 53
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    Surface movements in Bologna (Po Plain — Italy) detected by multitemporal DInSAR (2007)
    Elsevier
    Details
    Publikationsdatum: 2019-10-18
    Beschreibung: We studied the surface deformations affecting the southeastern sector of the Po Plain sedimentary basin, in particular the area of Bologna. To this aim an advanced DInSAR technique, referred to as DInSAR–SBAS (Small BAseline Subset), has been applied. This technique allows monitoring the temporal evolution of a deformation phenomenon, via the generation of mean deformation velocity maps and displacement time series from a data set of acquired SAR images. In particular, we have processed a set of SAR data acquired by the European Remote Sensing Satellite (ERS) sensors and compared the achieved results with optical levelling measurements, assumed as reference. The surface displacements detected by DInSAR SBAS from 1992 to 2000 are between 10 mm/year in the historical part of Bologna town, and up to 59 mm/year in the NE industrial and agricultural areas. Former measurements from optical levelling referred to 1897 show 2–3 mm/year vertical movements. This trend of displacement increased in the second half of the 20th century and the subsidence rate reached 60 mm/year. We compared the more recent levelling campaigns (in 1992 and late 1999) and DInSAR results from 1992 to 1999. The standard deviation of the difference between levelling data, projected onto the satellite Line Of Sight, and DInSAR results is 2 mm/year. This highlights a good agreement between the measurements provided by two different techniques. The explanation of soil movements based on interferometric results, ground data and geological observations, allowed confirming the anthropogenic cause (surface effect due to the overexploitation of the aquifers) and highlights a natural, tectonic, subsidence.
    Beschreibung: Published
    Beschreibung: 304-316
    Beschreibung: 1.10. TTC - Telerilevamento
    Beschreibung: JCR Journal
    Beschreibung: partially_open
    Schlagwort(e): InSAR ; surface deformation ; SAR interferometry ; 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::04.03. Geodesy::04.03.01. Crustal deformations ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
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  • 54
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    Unbekannt
    Reactive halogen chemistry in volcanic plumes (2007)
    AGU
    Details
    Publikationsdatum: 2023-01-19
    Beschreibung: Bromine monoxide (BrO) and sulphur dioxide (SO2) abundances as a function of the distance from the source were measured by ground-based scattered-light Multi AXis Differential Optical Absorption Spectroscopy (MAX-DOAS) in the volcanic plumes of Mt. Etna on Sicily, Italy in August-October 2004 and May 2005 and Villarica in Chile in November 2004. BrO and SO2 spatial distributions in a cross section of Mt. Etna’s plume were also determined by Imaging DOAS. We observed an increase in the BrO/SO2 ratio in the plume from below the detection limit near the vent to about 4.5 x 10-4 at 19 km (Mt. Etna) and to about 1.3 x 10-4 at 3 km (Villarica) distance, respectively. Additional attempts were undertaken to evaluate the compositions of individual vents on Mt. Etna. Furthermore, we detected the halogen species ClO and OClO. This is the first time that OClO could be detected in a volcanic plume. Using calculated thermodynamic equilibrium compositions as input data for a one–dimensional photochemical model, we could reproduce the observed BrO and SO2 vertical columns in the plume and their ratio as function of distance from the volcano as well as vertical BrO and SO2 profiles across the plume with current knowledge of multiphase halogen chemistry, but only when we assumed the existence of an ”effective source region”, where volcanic volatiles and ambient air are mixed at about 600°C (in the proportions of 60% and 40%, respectively)
    Beschreibung: Published
    Beschreibung: D06311
    Beschreibung: 3V. Proprietà chimico-fisiche dei magmi e dei prodotti vulcanici
    Beschreibung: JCR Journal
    Beschreibung: open
    Schlagwort(e): Chemistry ; Volcanic Plumes ; 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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  • 55
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    Unbekannt
    Real-time measurement of volcanic H2S and SO2 concentrations by UV spectroscopy (2006)
    American Geophysical Union
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: 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.
    Beschreibung: Published
    Beschreibung: 1652
    Beschreibung: partially_open
    Schlagwort(e): 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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  • 56
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    Field-based density measurements as tool to identify preeruption dome structure: set-up and first results from Unzen volcano, Japan (2006)
    Elsevier
    Details
    Publikationsdatum: 2020-01-08
    Beschreibung: For an improvement in the quality of conduit flow and dome-related explosive eruption models, knowledge of the preeruption or precollapse density of the rocks involved is necessary. As close investigation is impossible during eruption, the best substitute comes from quantitative investigation of the eruption deposits. The porosity of volcanic rocks is of primary importance for the eruptive behaviour and, accordingly, a key-parameter for realistic models of dome stability and conduit flow. Fortunately, this physical property may be accurately determined via density measurements. We developed a robust, battery-powered device for rapid and reliable density measurements of dry rock samples in the field. The density of the samples (sealed in plastic bags at 250 mbar) is determined using the Archimedean principle. We have tested the device on the deposits of the 1990–1995 eruption of Unzen volcano, Japan. Short setup and operation times allow up to 60 measurements per day under fieldwork conditions. The rapid accumulation of correspondingly large data sets has allowed us to acquire the first statistically significant data set of clast density distribution in block-and-ash flow deposits. More than 1100 samples with a total weight of 2.2 tons were measured. The data set demonstrates that the deposits of the last eruptive episode at Unzen display a bimodal density distribution, with peaks at 2.0F0.1 and 2.3F0.1 g/cm3, corresponding to open porosity values of 20 and 8 vol.%, respectively. We use this data set to link the results of laboratory-based fragmentation experiments to field studies at recently active lava domes.
    Beschreibung: Published
    Beschreibung: 65-75
    Beschreibung: partially_open
    Schlagwort(e): field-based density measurements ; dome ; Unzen volcano ; explosive eruption ; block-and-ash flow ; fragmentation behaviour ; volcanology ; 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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  • 57
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    Terminal settling velocity measurements of volcanic ash during the 2002-2003 Etna eruption by an X-band microwave rain gauge disdrometer (2005)
    AGU
    Details
    Publikationsdatum: 2021-05-17
    Beschreibung: This is the first report in the scientific literature of direct measurement of the terminal settling velocity of volcanic particles during an eruption. Field measurements using a continuous wave X-band disdrometer were carried out at Mt. Etna on 18 and 19 December 2002, when the explosive activity produced a 4 km high volcanic plume. These data allow the estimation of the intensity of the fallout and the measurement of the terminal settling velocities of the volcanic particles in real-time. The main results are: (1) the tested instrument detected coherent falling volcanic particles from 0.2 to 1 mm diameter; (2) measured terminal settling velocities were in agreement with both experimental and theoretical methods; (3) however, the measured velocities were clustered around few discrete values, rather than a range of velocities as would be expected if the particles were falling simultaneously and discretely. This new methodology has many new applications for local hazard mitigation and improved understanding of fallout processes.
    Beschreibung: Published
    Beschreibung: 1-5
    Beschreibung: partially_open
    Schlagwort(e): Volcanology: Explosive volcanism ; Volcanology: Remote sensing of volcanoes ; Volcanology: Instruments and techniques ; Volcanology: Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.02. Experimental volcanism ; 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)
    Materialart: article
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  • 58
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    Dynamics of magma ascent and fragmentation in trachytic versus rhyolitic eruptions (2005)
    Elsevier
    Details
    Publikationsdatum: 2020-10-29
    Beschreibung: We have performed a parametric study on the dynamics of trachytic (alkaline) versus rhyolitic (calc-alkaline) eruptions by employing a steady, isothermal, multiphase non-equilibrium model of conduit flow and fragmentation. The employed compositions correspond to a typical rhyolite and to trachytic liquids from Phlegrean Fields eruptions, for which detailed viscosity measurements have been performed. The investigated conditions include conduit diameters in the range 30–90 m and total water contents from 2 to 6 wt%, corresponding to mass flow rates in the range 106–108 kg/s. The numerical results show that rhyolites fragment deep in the conduit and at a gas volume fraction ranging from 0.64 to 0.76, while for trachytes fragmentation is found to occur at much shallower levels and higher vesicularities (0.81–0.85). An unexpected result is that low-viscosity trachytes can be associated with lower mass flow rates with respect to more viscous rhyolites. This is due to the non-linear combined effects of viscosity and water solubility affecting the whole eruption dynamics. The lower viscosity of trachytes, together with higher water solubility, results in delayed fragmentation, or in a longer bubbly flow region within the conduit where viscous forces are dominant. Therefore, the total dissipation due to viscous forces can be higher for the less viscous trachytic magma, depending on the specific conditions and trachytic composition employed. The fragmentation conditions determined through the simulations agree with measured vesicularities in natural pumice clasts of both magma compositions. In fact, vesicularities average 0.80 in pumice from alkaline eruptions at Phlegrean Fields, while they tend to be lower in most calc-alkaline pumices. The results of numerical simulations suggest that higher vesicularities in alkaline products are related to delayed fragmentation of magmas with this composition. Despite large differences in the distribution of flow variables which occur in the deep conduit region and at fragmentation, the flow dynamics of rhyolites and trachytes in the upper conduit and at the vent can be very similar, at equal conduit size and total water content. This is consistent with similar phenomenologies of eruptions associated with the two magma types.
    Beschreibung: Published
    Beschreibung: 93-108
    Beschreibung: partially_open
    Schlagwort(e): trachytic magma ; conduit flow ; eruption dynamics and numerical simulations ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
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  • 59
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    Water speciation and Sr isotopic exchange during water-melt interaction: a combined NMR-TIMS study on the Cretaio Tephra (Ischia Island,south Italy) (2005)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: In order to improve the microscopic understanding of the water-magma interaction process during explosive volcanism,volcanic glasses representative of deposits with sedimentological characteristics suggesting different water/melt ratios were studied by a combination of the nuclear magnetic resonance (NMR) and TIMS methods. The glasses were separated from pumices of two surge layers and one fallout bed of the Cretaio Tephra (Ischia Island,Italy), which is the product of an explosive eruption that occurred at Ischia in the second century BC. The 29Si CP^MAS NMR experiments indicate the occurrence of 1H^29Si dipolar couplings in glasses from the phreatomagmatic activity, suggesting the presence of hydrogen atoms in proximity of silicon atoms. This feature is not detected in the glass from the deposit of the magmatic explosion. 1H MAS NMR spectra reveal different peaks attributed to different hydrous species characterized by different motional properties. These include ‘rigid’ H2O groups isolated in the glass structure, more mobile water species and possibly structural hydroxyl groups. 1H MAS NMR spectra recorded after deuteration experiments of the glass at a temperature up to 300‡C revealed that the exchange reactions of the D2O vapor with hydrogen were limited to the most mobile water species,possibly on vesicle surfaces or in channels. The hydrogen concentration linearly correlates with the 87Sr/86Sr isotope ratio in glasses,suggesting isotopic tracer exchanges between the Sr dissolved in the water vapor and the Sr in the silicon-oxygen network during hydration. It is proposed that the uprising melt interacted with a hydrothermal system of seawater-derived fluids,characterized by relatively high Sr isotopic composition.
    Beschreibung: Published
    Beschreibung: 311-320
    Beschreibung: partially_open
    Schlagwort(e): Ischia ; Cretaio Tephra ; Water-melt interaction ; Nuclear magnetic resonance ; Sr isotopes ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 60
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    Intercomparison of volcanic gas monitoring methodologies performed on Vulcano Island, Italy (2005)
    American Geophysical Union
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: 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.
    Beschreibung: Published
    Beschreibung: L02610
    Beschreibung: partially_open
    Schlagwort(e): 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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  • 61
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    Seismoacoustic measurements during the July–August 2001 eruption of Mt. Etna volcano, Italy (2005)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: On July 18, 2001, two main eruptive vents opened on the southern flank of Mount Etna volcano (Italy) at ~2100 m and ~2550 m a.s.l., respectively. The former vent fed mild strombolian activity and lava flows, while the latter represented the main explosive vent, producing strong phreato-magmatic explosions. Explosions at this latter vent, however, shifted to a strombolian style in the following days, before switching back to phreato-magmatic activity towards the end of the eruption, which ended on August 9, 2001. On August 3, a small seismoacoustic array was deployed close to the eruptive vents. The array was composed of three stations, which recorded seismic and infrasonic waves coming from both of the eruptive vents. A further seismoacoustic station, equipped with a thermal-infrared sensor, was also installed several kilometers north of the first array. Seismic signals relating to the strombolian activity at the 2100-m vent were characterized by a strong decompression at the source. Analysis of the time delays between seismic, infrasonic and infrared event onsets also revealed that ejection velocities during explosions from both vents were subsonic. Time delays between the onset of explosive events apparent in the infrared and infrasound data indicated that the explosion source at the 2550-m vent was located 220–250 m below the crater rim. In comparison, the depth of the seismic source was estimated to be between 230 and 335 m below the rim. This converts to 120–150 and 130–235 m below the preexisting ground surface. In addition, time delays between seismic and infrasonic signals recorded for the lower (2100 m) vent also revealed a seismic source that was no more than a few tens of meters deeper than the fragmentation surface.
    Beschreibung: Published
    Beschreibung: 219-230
    Beschreibung: partially_open
    Schlagwort(e): Mt. Etna ; explosive eruptions ; arrays ; seismic ; infrasonic and thermal data ; 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 ; 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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  • 62
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    Paroxysmal summit activity at Mt. Etna (Italy) monitored through continuous soil radon measurements (2005)
    AGU
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: Soil radon emissions have been proved as a useful tool for predicting earthquakes and volcanic eruptions and furthermore aided in determining the location of active faults. Continuous radon monitoring was carried out near Southeast Crater of Mt. Etna in September–November 1998, during a period of frequent eruptive episodes at that crater. Radon anomalies were detected when eruptive episodes and the accompanying volcanic tremor became increasingly intense: no anomalies in radon activity were observed during the first five, and weaker, eruptive episodes, whereas significant spikes in radon activity preceded the latter five episodes by ≥46 hours. This probably reflects increased gas leakage through fractures intersecting the shallow plumbing system, as gas pressure in the Southeast Crater conduit became higher with time. Radon monitoring thus might serve to better understand eruptive mechanisms and possible precursors, making further studies in this field a promising perspective.
    Beschreibung: Published
    Beschreibung: 1-4
    Beschreibung: partially_open
    Schlagwort(e): Seismology: Volcano seismology ; Structural Geology: Role of fluids ; Volcanology: Volcano monitoring ; Volcanology: Instruments and techniques ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 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
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 63
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    Chronology and complex volcanic processes during the 2002–2003 flank eruption at Stromboli volcano (Italy) reconstructed from direct observations and surveys with a handheld thermal camera (2005)
    AGU
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: Effusive activity at Stromboli is uncommon, and the 2002–2003 flank eruption gave us the opportunity to observe and analyze a number of complex volcanic processes. In particular, the use of a handheld thermal camera during the eruption allowed us to monitor the volcano even in difficult weather and operating conditions. Regular helicopter-borne surveys with the thermal camera throughout the eruption have significantly improved (1) mapping of active lava flows; (2) detection of new cracks, landslide scars, and obstructions forming within and on the flanks of active craters; (3) observation of active lava flow field features, such as location of new vents, tube systems, tumuli, and hornitos; (4) identification of active vent migration along the Sciara del Fuoco; (5) monitoring of crater's inner morphology and maximum temperature, revealing magma level changes within the feeding conduit; and (6) detection of lava flow field endogenous growth. Additionally, a new system developed by A. J. L. Harris and others has been applied to our thermal data, allowing daily calculation of effusion rate. These observations give us new insights on the mechanisms controlling the volcanic system.
    Beschreibung: Published
    Beschreibung: 1-23
    Beschreibung: partially_open
    Schlagwort(e): volcano monitoring ; thermal mapping ; flank eruption ; Stromboli volcano ; 04. Solid Earth::04.08. Volcanology::04.08.02. Experimental volcanism ; 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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  • 64
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    A PTFE membrane for the in situ extraction of dissolved gases in natural waters: Theory and applications (2005)
    American Geophysical Union
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: 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.
    Beschreibung: - European Social Fund.
    Beschreibung: Published
    Beschreibung: Q09005
    Beschreibung: partially_open
    Schlagwort(e): 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
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 65
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    Accurate measurement of volcanic SO2 flux: Determination of plume transport speed and integrated SO2 concentration with a single device (2005)
    American Geophysical Union
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: 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.
    Beschreibung: Published
    Beschreibung: Q02003
    Beschreibung: partially_open
    Schlagwort(e): 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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  • 66
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    Birth, growth and morphologic evolution of the `Laghetto´ cinder cone during the 2001 Etna eruption (2005)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: We have undertaken detailed observations of the formation of the `Laghetto´ cinder cone, a new cone that formed during a 2-week period of intense activity in Piano del Lago, on the upper slopes of Mount Etna in summer 2001. We describe the events leading to the formation of a small graben, the formation of pit craters on the base of the graben, the onset of phreatomagmatic activity, a transition to intense Strombolian activity, and a return to phreatomagmatic activity as the eruption came to an end. We discuss the reasons for these transitions, and describe the morphological development of the cone during these events. Arcuate cracks on the southern part of the cone were related to withdrawal of magma at the end of the eruption. Other slope instabilities that developed during the eruption include the formation of small radial grain flows on the outer flanks of the cone and the collapse into the crater of part of the crater rim. Some of the failure planes we observed were first identified using a FLIR TM 695 thermal infrared camera. This is the first time that infrared thermography has been used to detect instability of volcanic structures. Results obtained during this test case demonstrate that thermal cameras are a very useful tool for studies of volcanic instability.
    Beschreibung: Published
    Beschreibung: 225-239
    Beschreibung: partially_open
    Schlagwort(e): Etna volcano ; cinder cone ; volcano instability ; thermal images ; phreatomagmatic activity ; 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
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  • 67
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    Chemical mapping of a fumarolic field: La Fossa Crater, Vulcano Island (Aeolian Islands, Italy) (2005)
    American Geophysical Union
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: 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.
    Beschreibung: Published
    Beschreibung: L13309
    Beschreibung: partially_open
    Schlagwort(e): 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
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 68
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    Fluid circulation and structural discontinuities inside Misti volcano (Peru) inferred from self-potential measurements (2005)
    Elsevier
    Details
    Publikationsdatum: 2017-04-04
    Beschreibung: One of the seven potentially active andesite stratovolcanoes in southern Peru, Misti (5822 m), located 17 km northeast and 3.5 km above Arequipa, represents a major threat to the population (f900,000 inhabitants). Our recent geophysical and geochemical research comprises an extensive self-potential (SP) data set, an audioâ magnetotelluric (AMT) profile across the volcano and CO2 concentrations in the soil along a radial profile. The SP survey is the first of its kind in providing a complete mapping of a large andesitic stratovolcano 20 km in diameter. The SP mapping enables us to analyze the SP signature associated with a subduction-related active volcano. The general SP pattern of Misti is similar to that of most volcanoes with a hydrogeologic zone in the lower flanks and a hydrothermal zone in the upper central area. A quasi-systematic relationship exists between SP and elevation. Zones with constant SP/altitude gradients (Ce) are observed in both hydrogeologic (negative Ce) and hydrothermal (positive Ce) zones. Transition zones between the different Ce zones, which form a concentric pattern around the summit, have been interpreted in terms of lateral heterogeneities in the lithology. The highest amplitudes of SP anomalies seem to coincide with highly resistive zones. The hydrothermal system 6 km in diameter, which extends over an area much larger than the summit caldera, may be constrained by an older, concealed collapse caldera. A sealed zone has apparently developed through alteration in the hydrothermal system, blocking the migration of CO2 upward. Significant CO2 emanations are thus observed on the lower flanks but are absent above the hydrothermal zone.
    Beschreibung: - Institut de Recherche pour le Developpement (IRD) - Instituto Geofısico del Peru´ (IGP)
    Beschreibung: Published
    Beschreibung: 343-360
    Beschreibung: partially_open
    Schlagwort(e): Misti volcano ; self-potential ; audioâ magnetotelluric ; electrical resistivity ; structural discontinuity ; hydrothermal system ; Peru ; 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)
    Materialart: article
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  • 69
    Digitale Medien
    Digitale Medien
    New Syntheses of Flavones from Diels-Alder Reactions of 2-Styrylchromones with ortho-Benzoquinodimethanes (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 135-139 
    Details
    ISSN: 1434-193X
    Schlagwort(e): Flavones ; Chromones ; ortho-Benzoquinodimethanes ; Diels-Alder reactions ; NMR ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: -The first reported cycloaddition reactions of 2-styrylchromones with ortho-benzoquinodimethane afforded 2-[2-(3-aryl-1,2,3,4-tetrahydronaphthyl)]chromones. These cycloadducts were converted into the corresponding 2-[2-(3-arylnaphthyl)]chromones (benzoflavone derivatives) by bromination/dehydrobromination processes. These benzoflavone derivatives were also obtained in one-pot cycloaddition reactions of 2-styrylchromones with ortho-benzoquinodibromomethane.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 70
    Digitale Medien
    Digitale Medien
    The Structures of a Tetracarba-nido-octaborane(8) and a Novel Spiro Derivative of a 2,3,5-Tricarba-nido-hexaborane(7) (1999)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1999 (1999), S. 533-537 
    Details
    ISSN: 1434-1948
    Schlagwort(e): Ab initio calculations ; Carboranes ; NMR ; X-ray analysis ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Hydroboration of bis(diethylboryl)ethyne (1) with tetraethyldiborane(6) leads to a B-ethyl-substituted tetracarba-nido-octaborane 2, a spiro-carborane 3, which belongs to the 2,3,5-tricarba-nido-carborane family, and a hexacarba-arachno-dodecaborane(12) 4, along with polymeric material. The X-ray structure analysis of carborane 2, determined here, is fully consistent with the structure deduced earlier from NMR data. The structure of 3 in solution was established by theoretical analysis of its NMR data. Ab initio calculations of the structures of 2b and 3b (b denotes the B-metyhl-substituted derivatives) and the comparison of calculated with experimental NMR data support the suggested structures of 2 and 3 in solution. The calculated structure of the carborane cage of 2a also agrees with the experimental geometry of 2.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 71
    Digitale Medien
    Digitale Medien
    Synthesis, Structure, and Stereodynamics of an N,N-Chiral “Proton Sponge” (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 2501-2510 
    Details
    ISSN: 1434-193X
    Schlagwort(e): Proton Sponges ; N-Chirality ; Isotopic labelling ; Stereodynamics ; NMR ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: 1,8-Bis(N-benzyl-N-methylamino)naphthalene (2) and its hydrogen iodide salt [2H]+[I]- were synthesised from 1,8-diaminonaphthalene. The thermodynamic diastereomer ratios of (2) and [2H]+ in [D7]DMF are 73.4:26.6 and 89.7:10.3 respectively at 293 K. The solid state structures of the major dl-(RNRNSNSN) diastereomers were determined by single crystal X-ray diffraction. The minor diastereomers were shown to be the meso-(RNSN) forms by performing 1H-NMR NOE studies on isotopically desymmetrized 1-(N-benzyl-N-[13C]-methylamino)-8-(N′-benzyl-N′-methylamino)naphthalene [13C]-2 and the salt [13C]-[2H]+. In [D7]DMF at 298 K, the meso form of the free base 2 is 0.6 (± 0.07) kcal·mol-1 less stable than the dl form (ΔH° = -0.64 (±0.03) kcal·mol-1; ΔS° = -0.18 (±0.13) cal·K-1mol-1) and the activation barriers for interconversion are ca. 14.2 (±0.4) and 14.8 (±0.4) kcal·mol-1 respectively. The effect of solvent polarity on the entropy and enthalpy change on approach to the transition state was studied. An approximate correlation with the solvent dielectric constant was found for both ΔH# and ΔS# and this may be ascribed to the development of a net dipole in the transition state due to substantially different hybridisation and geometry at the two nitrogen centres.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
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  • 72
    Digitale Medien
    Digitale Medien
    Structure analysis of a soluble polysiloxane-block-polyimide and kinetic analysis of the solution imidization of the relevant polyamic acid (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2237-2245 
    Details
    ISSN: 0887-624X
    Schlagwort(e): NMR ; polysiloxane, polysiloxane-block-polyimide ; solution imidization ; kinetic analysis ; structure analysis ; spin-lattice relaxation time ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A series of polysiloxane-block-polyimides were synthesized by solution imidization of the polyamic acids derived from the combination of 3,3′,4,4′-diphenylsulfonetetracarboxylic dianhydride (DSDA), 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP), and diamino(polysiloxane) (PSX (Mw = 750)) in N-methyl-2-pyrrolidone (NMP). Their structures were analyzed by 1H-, 13C-, and 29Si-NMR spectra as well as by IR spectroscopy. The solid-state NMR spectrum was also measured to determine the spin-lattice relaxation time of the copolyimides. The observed relaxation times of both aromatic and polysiloxane segments were similar in the copolyimides having 10-30 wt % of PSX, while those in the copolyimide with 50 wt % of PSX was significantly different. This may be attributed to the morphology change due to the increase in PSX composition in the polymer backbone. The reduced viscosity of the copolyimides could be controlled by changing the monomer ratio in the feed or by adding an end-capping reagent such as phthalic anhydride into the polymerization system. The kinetic study of the solution imidization revealed that the imidization reaction obeyed second-order kinetics. The activation energy calculated for this imidization was 99.2 kJ/mol, being similar to that for the imidization of the DSDA-based aromatic polyimides. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2237-2245, 1998
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
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  • 73
    Digitale Medien
    Digitale Medien
    Investigation of the microstructure of metallocene-catalyzed norbornene-ethylene copolymers using NMR spectroscopy (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1633-1638 
    Details
    ISSN: 0887-624X
    Schlagwort(e): cyclic olefin copolymers ; norbornene ; metallocene catalysts ; NMR ; microstructure ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Norbornene-ethylene copolymers were prepared using the metallocene catalyst ethylene bis (indenyl) zirconium dichloride with MAO, and their microstructure was characterized with 1H-NMR and 13C-NMR methods. From a Cosy 1H-NMR spectrum it was found that all norbornene units are enchained in the exo-configuration. The sequence distribution of norbornene units was investigated using 13C-1H correlations, hmqc for one-bond correlations, and hmbc for two- or three-bond correlations. It was shown that norbornene diads were formed at a high norbornene content (45 mol %). When further increasing the norbornene incorporation (66 mol %) a number of new signals were obtained. A Cosy 1H-NMR spectrum revealed a new crosspeak which, according to the corresponding 13C-NMR shifts (hmqc), correlated well with a terminal unit of a trimer of norbornene. This means that at very high norbornene contents, norbornene triads can be formed. Because the formation of isotactic norbornene triads is very difficult to understand from a sterical point of view, an epimerization process causing stereoirregularities in the norbornene triad is proposed. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1633-1638, 1998
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
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  • 74
    Digitale Medien
    Digitale Medien
    Stereochemical and compositional assignment of acrylonitrile/methyl methacrylate copolymers by DEPT and inverse HECTOR NMR spectroscopy (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1081-1092 
    Details
    ISSN: 0887-624X
    Schlagwort(e): NMR ; microstructure ; acrylonitrile/methyl methacrylate copolymer ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The acrylonitrile/methyl methacrylate copolymers of different monomer concentration were prepared by photo polymerization using uranyl ion as initiator. The carbon 13 and proton spectra of these copolymers are overlapping and complex. The complete spectral assignment of the 13C- and 1H-NMR spectra were done with the help of Distortionless Enhancement by Polarization Transfer (DEPT) and two dimensional 13C-1H Heteronuclear Single Quantum Correlation (HSQC) experiments. The methylene, methine and the methyl carbon resonances show both stereochemical (triad level) and compositional (dyad, triad, tetrad, pentad and hexad level) sensitivity. 2D Double Quantum Filtered Correlated Spectroscopy (DQFCOSY) experiment was used to ascertain the various geminal couplings between the methylene protons. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1081-1092, 1998
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
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  • 75
    Digitale Medien
    Digitale Medien
    Synthesis of novel polyaryl(ether-ketones) with tert-butyl pendent groupsDedicated to Prof. F. J. Baltaá Calleja on the occasion of his 60th birthday. (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1251-1256 
    Details
    ISSN: 0887-624X
    Schlagwort(e): ether ketones ; synthesis ; NMR ; thermal properties ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Linear polyaryl(ether ketones) containing tert-butyl pendent groups were prepared from aromatic hydrocarbons and aromatic diacid chlorides, both classes of monomers containing tert-butyl pendent groups. The polymers were prepared in high yield and high molecular weight by low-temperature precipitation polycondensation in 1,2-dichloroethane. The presence of meta-oriented moieties and bulky pendent groups played a beneficial role with regard to solubility, while the thermal transitions and thermal resistance were not greatly impaired relative to conventional all para-oriented polyaryl(ether-ketones). The current polyaryl(ether-ketones) showed glass transition temperatures in the range 170-240°C and decomposition temperatures, as measured by TGA, of about 500°C. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1251-1256, 1998
    Zusätzliches Material: 3 Ill.
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  • 76
    Digitale Medien
    Digitale Medien
    NMR and semi-empirical study of the tautomerism of­2,2′-bisbenzimidazolyl (1998)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 11 (1998), S. 411-418 
    Details
    ISSN: 0894-3230
    Schlagwort(e): 2,2′-bisbenzimidazolyl ; tautomerism ; NMR ; semi-empirical calculations ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: A dynamic NMR study of the tautomerism of 2,2′-bisbenzimidazolyl in DMSO-d6 and a mechanistic interpretation of the process, based on a stepwise, single-proton transfer and formation of a zwitterionic intermediate, are presented. This interpretation is substantiated by semi-empirical calculations of the postulated intermediate and transition state, that yield results which are compared with previous studies on related aliphatic systems. © 1998 John Wiley & Sons, Ltd.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 77
    Digitale Medien
    Digitale Medien
    Enantioselective synthesis of α-aminophosphonic acid derivatives by hydrogenation (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 564-572 
    Details
    ISSN: 0899-0042
    Schlagwort(e): asymmetric hydrogenation ; aminophosphine phosphinites ; rhodium complexes ; dehydro aminophosphonic acids ; NMR ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Chiral α-aminophosphonic acid derivatives are efficiently synthesized by asymmetric hydrogenation of the prochiral N-acyl-α,β-dehydroaminophosphonates. PROPRAPHOS-Rh-catalysts from readily available (S)- and (R)-Propranolol proved to be suitable in the homogenous reaction affording an enantiomeric excess of 87-92% with high rate. The aminophosphonic acid derivatives and precursors were fully characterized by 1H, 13C, and 31P NMR spectroscopy. Chirality 10:564-572, 1998. © 1998 Wiley-Liss, Inc.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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  • 78
    Digitale Medien
    Digitale Medien
    Stereochemistry of polycyclohexyl systems (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 159-168 
    Details
    ISSN: 0899-0042
    Schlagwort(e): symmetry ; conformation ; chirality ; stereochemistry ; NMR ; rotational barrier ; interconversion graph ; gear meshing ; molecular propellers ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The static and dynamic stereochemistries of tricyclohexylmethane, tetracyclohexylmethane, and tetracyclohexylethene are reviewed. Chirality 10:159-168, 1998. © 1998 Wiley-Liss, Inc.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/chir.25
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  • 79
    Digitale Medien
    Digitale Medien
    A New Class of Oligonuclear Platinum-Thallium Compounds with a Direct Metal-Metal Bond - 3. Unusual Equilibria in Aqueous Solution (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 565-570 
    Details
    ISSN: 1434-1948
    Schlagwort(e): Equilibrium ; Metal-metal bond ; Stability constants ; Platinum ; Thallium ; NMR ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A new series of four binuclear platinum-thallium cyano compounds containing a direct and unsupported by ligands metal-metal bond has been prepared in aqueous solution. These compounds are represented by the formula[(NC)5Pt-Tl(CN)n-1](n-1)- (n = 1-4 for compounds I, II, III IV, respectively) and [(NC)5Pt-Tl-Pt(CN)5]3- (for compound V). The oligonuclear complexes are synthesised according to the reaction mPt(CN)42- + Tl3+ + nCN- █[PtmTl(CN)4m+n]3-2-n. Thus, there occurs a change of the coordination number of the Pt center from four (square planar) to six (octahedral). Consequently, the formation of binuclear platinum-thallium cyano compounds involves at least two steps: (i) formation of metal-metal bond and (ii) formation of (NC)5Pt- unit by a cyanide transfer process. - The complexes exist in an equilibrium, which also includes the parent complexes Pt(CN)42- and Tl(CN)n3-n (n = 0-4), and can be controlled by varying the cyanide concentration and/or pH of the solution. The stability constants of the compounds βN =[PtmTl(CN)4m+n3-2m-n{[Pt(CN)42-]m · [Tl3+] · [CN-]n} have been determined by means of multinuclear NMR (195Pt, 205Tl): logβN = 19.9±0.4, 30.7±0.3, 38.6±0.3, and 44.8±0.2 for I, II, III and IV(m = 1, n = 1-4), and 32.1±0.3 for V(m = 2, n = 2), respectively, (in 1 M NaClO4 as ionic medium, at 25 oC). To our knowledge, the present work constitutes the first detailed equilibrium study of metal-metal bonded compounds; it indicates that also other cluster formation reactions described in the literature may represent real equilibria.
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  • 80
    Digitale Medien
    Digitale Medien
    VTF to arrhenius crossover in temperature dependence of conductivity in (PEG)xNH4ClO4 polymer electrolyte (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 1201-1209 
    Details
    ISSN: 0887-6266
    Schlagwort(e): polymer electrolytes ; NMR ; conductivity ; glasses ; Arrhenius and VTF dependences ; Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: We have studied the temperature variation of conductivity and 1H NMR linewidth of (PEG)xNH4ClO4 (x = 20, 30, 46, 100, 200, & 1000) polymer electrolyte systems. The temperature dependence of the conductivity shows two distinct behaviors, the low temperature VTF dependence crossing over to Arrhenius dependence at higher temperatures. The departure from the VTF behavior is found to be composition dependent. NMR spectra indicate the presence of large fractions of crystalline regions that start to melt around the crossover temperature. We understand the deviation from the VTF behavior as a consequence of this crystalline to elastomer transition. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1201-1209, 1998
    Zusätzliches Material: 9 Ill.
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  • 81
    Digitale Medien
    Digitale Medien
    Conformation and membrane activity of an analogue of the peptaibol antibiotic trichogin GA IV with a lipophilic amino acid at the N-terminus (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 4 (1998), S. 389-399 
    Details
    ISSN: 1075-2617
    Schlagwort(e): conformational analysis ; lipo-amino acid ; membrane activity ; NMR ; peptide antibiotic ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: We have synthesized by solution-phase methods two analogues of the 11-residue lipopeptaibol antibiotic trichogin GA IV in which the N-terminal n-octanoyl group is replaced either by an N-acetylated 2-amino-2-methyl-l-undecanoic acid or by an N-acetylated α-aminoisobutyric acid. CD, FTIR absorption, and NMR analyses unequivocally show that the main structural features of trichogin GA IV are preserved in these analogues. Since only the peptide containing the lipophilic chain exhibits membrane-modifying properties, these results strongly support the view that moving the long acyl moiety from the Nα-blocking group to the side chain of the N-terminal extra-residue does not affect the conformational properties or the membrane activity of trichogin GA IV. © 1998 European Peptide Society and John Wiley & Sons, Ltd.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 82
    Digitale Medien
    Digitale Medien
    Conformational sampling of bioactive conformers: a low-temperature NMR study of 15N-Leu-enkephalin (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 4 (1998), S. 253-265 
    Details
    ISSN: 1075-2617
    Schlagwort(e): Opioids ; enkephalin ; selectivity ; conformation ; NMR ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Conformational studies of enkephalins are hampered by their high flexibility which leads to mixtures of quasi-isoenergetic conformers in solution and makes NOEs very difficult to detect in NMR spectra. In order to improve the quality of the NMR data, Leu-enkephalin was synthesized with 15N-labelled uniformly on all amide nitrogens and examined in a viscous solvent medium at low temperature. HMQC NOESY spectra of the labelled Leu-enkephalin in a DMSOd6/H2O mixture at 275 K do show numerous NOEs, but these are not consistent with a single conformer and are only sufficient to describe the conformational state as a mixture of several conformers. Here a different approach to the structure-activity relationships of enkephalins is presented: it is possible to analyse the NMR data in terms of limiting canonical structures (i.e. β- and γ-turns) and finally to select only those consistent with the requirements of δ selective agonists and antagonists. This strategy results in the prediction of a family of conformers that may be useful in the design of new δ selective opioid peptides. © 1998 European Peptide Society and John Wiley & Sons, Ltd.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 83
    Digitale Medien
    Digitale Medien
    Effect of extracellular glutamine concentration on primary and secondary metabolism of a murine hybridoma: An in vivo 13C nuclear magnetic resonance study (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 57 (1998), S. 172-186 
    Details
    ISSN: 0006-3592
    Schlagwort(e): hybridoma ; futile cycling ; hollow fiber bioreactor ; glutamine ; NMR ; C-13 ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The effect of changes in extracellular glutamine level on metabolism of a murine hybridoma was examined with in vivo nuclear magnetic resonance (NMR) spectroscopy. Cells were cultured in a hollow-fiber bioreactor at high cell density to allow intracellular metabolite levels to be determined on a metabolically relevant time scale. Steady infusions of [1-13C] glucose were used to label glycolytic and tricarboxylic acid cycle intermediates, which permitted continuous monitoring with NMR spectroscopy during changes in environmental glutamine level. Samples of the extracellular medium were also analyzed to determine the effect of glutamine on other metabolites associated with primary and secondary metabolism. The changes in glutamine concentration had several effects on primary and secondary metabolism, depending on the rate the changes were made. For a brief reduction in feed glutamine concentration from 4 to 0 mM (which produced a rapid change from 0.67 to ∼0 mM in residual glutamine), large changes were observed in the rate of consumption of metabolites normally associated with energy production. Antibody synthesis was strongly stimulated and nitrogen metabolism was significantly altered. For a more prolonged reduction from 2.4 to 1.2 mM (which produced a slower reduction from 0.30 to 0.08 mM in residual glutamine), much smaller changes were observed even though the concentration of glutamine at the reduced feed level was very low. Energy metabolism did not appear to be limited by glutamine at 0.08 mM, which suggests that significant futile cycling may occur in energy producing pathways when excess glucose and glutamine are available. However, this concentration of extracellular glutamine appeared to affect some anabolic pathways, which require amino groups from glutamine. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 57: 172-186, 1998.
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  • 84
    Digitale Medien
    Digitale Medien
    Characterization of the diffusive properties of biofilms using pulsed field gradient-nuclear magnetic resonance (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 60 (1998), S. 283-291 
    Details
    ISSN: 0006-3592
    Schlagwort(e): diffusion ; biofilms ; gels ; NMR ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The mobility of water in intact biofilms was measured with pulsed field gradient nuclear magnetic resonance (PFG-NMR) and used to characterise their diffusive properties. The results obtained with several well-defined systems, viz. pure water, agar, and agar containing inert particles or active bacteria were compared to glucose diffusion coefficients measured with micro-electrodes and those calculated utilising theoretical diffusion models. A good correspondence was observed indicating that PFG-NMR should also enable the measurement of diffusion coefficients in heterogeneous biological systems. Diffusion coefficients of several types of natural biofilms were measured as well and these results were related to the physical biofilm characteristics. The values had a high accuracy and reflected the properties of a sample of ca. 100 biofilms, while non-uniformity or non-geometrical shapes did not negatively influence the results. The monitored PFG-NMR signal contains supplementary information on e.g. cell fraction or spatial organisation but quantitative analysis was not yet possible. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 60: 283-291, 1998.
    Zusätzliches Material: 7 Ill.
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  • 85
    Digitale Medien
    Digitale Medien
    7Li and 23Na NMR studies of transmembrane cation transport mediated by ionophore lasalocid A (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 4 (1998), S. 15-20 
    Details
    ISSN: 1075-2617
    Schlagwort(e): ion transport ; kinetics ; lithium ; NMR ; shift reagent ; vesicles ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Ion transport across phospholipid vesicles was studied by 7Li and 23Na-NMR using an aqueous anionic paramagnetic shift reagent, dysprosium nitrilotriacetate [Dy(NTA)2]3-, mediated by ionophores, lasalocid A and A23187. The intra- and extracellular 7Li and 23Na-NMR signals were well separated (20 Hz) at mM concentration of the shift reagent. The observed data on the rate constant for lithium transport across DPPC vesicles at various concentrations of the ionophores indicated that lasalocid A is a more efficient carrier for lithium ion compared with the sodium ion transport by this ionophore, while A23187 was not specific to either of the ions (Li or Na). ©1998 European Peptide Society and John Wiley & Sons, Ltd.
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  • 86
    Digitale Medien
    Digitale Medien
    Solution conformation of an immunogenic peptide from HRV2: comparison with the conformation found in a complex with a Fab fragment of an anti-HRV2 neutralizing antibody (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 4 (1998), S. 101-110 
    Details
    ISSN: 1075-2617
    Schlagwort(e): NMR ; random coil ; rhinovirus ; synthetic vaccine ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The conformation of a [15]-peptide (H-VKAETRLNPDLQPTE-NH2) from VP2 of rhinovirus HRV2 complexed with a Fab fragment was previously shown by X-ray crystallographic studies to be similar to the one found in the corresponding region of HRV1A. Antibodies raised against this peptide bind to and neutralize HRV2. In order to identify structural features preserved in solution that may explain the ability of this short peptide to mimic the structure of the protein surface, the peptide has been studied by NMR in aqueous solution as well as under denaturing conditions.The peptide is shown to be a random coil in solution. However, the sequence forming a 310 helix in the complex is biased into a helical conformation according to NOE intensity data as well as from urea and pH titrations. This sequence adopts the same conformation in an unrelated protein. NOE data suggest that a β-turn found in the complex may be sampled in solution. Also, Glu4, interacting with Arg6 in the crystal, has a reduced pKa value in solution. It is concluded that the local structure present in the random coil state of VP2(156-170) contains enough information to direct the production of antibodies that bind to and neutralize HRV2. © 1998 European Peptide Society and John Wiley & Sons, Ltd.
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  • 87
    Digitale Medien
    Digitale Medien
    A conformational study in solution of pro-somatostatin fragments by NMR and computational methods (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 4 (1998), S. 305-318 
    Details
    ISSN: 1075-2617
    Schlagwort(e): pro-somatostatin ; β-turn ; NMR ; computational methods ; conformational analysis ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The results of a conformational study by nuclear magnetic spectroscopy and computational methods on a series of point-mutated synthetic peptides, containing 14 amino acid residues and mimicking the region containing the Arg-Lys dibasic cleavage site of pro-somatostatin, have confirmed the possible role of a well defined secondary structure in the recognition phenomenon by processing enzymes.The importance of the residues located near the Arg-Lys dibasic site in the C-terminal region of the pro-hormone for the cleavage of the precursor into somatostatin-14 has been confirmed. The present structural analysis indicates the occurrence of two β-turns in the 4-7 and 11-14 regions, flanking the cleavage site, for all the peptides recognized as substrates by the processing enzyme.Interestingly, in the point-mutated analogue not processed by the enzyme and containing the replacement of proline by alanine in position 5 the first β-turn is displaced by one residue and involves the Ala5-Arg8 segment. This observation may explain the lack of recognition by the maturation enzyme. © 1998 European Peptide Society and John Wiley & Sons, Ltd.
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  • 88
    Digitale Medien
    Digitale Medien
    Synthesis and characterization of arsenobetaine and arsenocholine derivatives (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 12 (1998), S. 635-641 
    Details
    ISSN: 0268-2605
    Schlagwort(e): arsenobetaine ; arsenocholine ; non-hygroscopic ; NMR ; FAB MS ; ICP MS ; synthesis ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Multigram quantities of arsenobetaine bromide and arsenocholine iodide were synthesized from trimethylarsine using uncomplicated techniques. Arsenobetaine bromide and arsenocholine iodide are both non-hygroscopic. Arsenocholine iodide is, however, light-sensitive and should be used with actinic glassware. Both compounds were characterized by elemental and spectroscopic techniques and found to be suitable for use as primary analytical standards. © 1998 John Wiley & Sons, Ltd.
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  • 89
    Digitale Medien
    Digitale Medien
    Synthesis and characterization of diorganotin(IV) complexes of N-(2-pyridylmethylene)arylamines and mutagenicity testing in vivo of Et2SnCl2·[L4=N-(2-pyridylmethylene)-4-toluidine] (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 12 (1998), S. 503-513 
    Details
    ISSN: 0268-2605
    Schlagwort(e): organotin ; N-(2-pyridylmethylene)arylamines ; IR ; NMR ; Mössbauer ; mutagenicity ; sister chromatid exchange ; cell cycle delay ; bone-marrow cells ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Diorganotin(IV) dichloride complexes of the type R2SnCl2·L (R = methyl, ethyl, vinyl, t-butyl, n-butyl or phenyl; L = N-(2-pyridylmethylene)arylamine) have been synthesized and characterized on the basis of IR, NMR and 119Sn Mössbauer studies. Investigation of the complexes indicated that N-(2-pyridylmethylene)arylamines form distorted trans-octahedral complexes with R2SnCl2 similar to the well-known R2SnCl2·L. Cytogenetic toxicology testing has been performed for Et2SnCl2·L4 [L4 = N-(2-pyridylmethylene)-4-toluidine] in mouse bone-marrow cells in vivo since such testing is a regulatory requirement before new drugs are released. This tin compound induced delay in cell-cycle kinetics and sister chromatid exchanges (SCEs) significantly. The effect of Et2SnCl2·L4 was greater when endogenous glutathione (GSH) was depleted by buthionine sulphoximine (BSO). It seems that Et2SnCl2·L4 induces SCEs due to formation of adduct by binding on DNA which could interfere in DNA synthesis and cause delay in cell proliferation. Depletion of GSH could reduce the shielding effect of GSH on chromatin and allows more Et2SnCl2·L4 to bind on DNA. © 1998 John Wiley & Sons, Ltd.
    Zusätzliches Material: 1 Ill.
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  • 90
    Digitale Medien
    Digitale Medien
    Diorganotin(IV)-2-mercaptopyrimidine complexes (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 12 (1998), S. 861-871 
    Details
    ISSN: 0268-2605
    Schlagwort(e): diorganotin ; Pyrimidine ; complex ; Mössbauer ; IR ; NMR ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The complexes formed between the diorganotin(IV) moieties, R2Sn(IV), and the ligand 2-mercaptopyrimidine, (H)SPym, were investigated. Complexes R2SnHal(SPym) and R2Sn(SPym)2 [R = Me, iPr, nBu, iBu, tBu, cyclohexyl(Cy), Ph] were synthesized, and characterized by elemental analysis. In the solid state, chelation of SPym through S and N donors was established by IR spectroscopy, and the nature of the environment of tin centers was investigated by 119Sn Mössbauer spectroscopy. From the dynamics of 119Sn nuclei determined by variable-temperature measurements on representative compounds [Me2SnCl(SPym) and Cy2SnBr(SPym)], as well as by point-charge model treatment of nuclear quadrupole splitting parameters, it was inferred that Me2SnCl-­(SPym) may assume a trans-Me2 octahedral coordination geometry around tin in a monodimensional polymer, or a monomeric trigonal-bipyramidal structure (distorted). The latter type of structure was assigned to the other R2SnHal(SPym) species, while R2Sn(SPym)2 complexes assume a trans-octahedral, or skew trapezoidal, tin environment. In CHCl3-CDCl3 solutions, monomeric species occur (according to vapor-pressure osmometry), where 1H and 13C NMR spectroscopic parameters of SPym indicate the persistence of Sn chelation by S and N donor atoms. The Me2SnCl(SPym) species assume trigonal-bipyramidal structures with a chelating SPym ligand, in CDCl3 and C2H5OH solutions, according to the coupling constants 1J(119Sn,13C), as well as IR and 119Sn Mössbauer spectroscopic data. 119Sn NMR parameters fully correspond with data for the homologous complexes with 2-mercaptopyridine. Copyright © 1998 John Wiley & Sons, Ltd.
    Zusätzliches Material: 5 Ill.
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  • 91
    Digitale Medien
    Digitale Medien
    Ab initio prediction of 15N-NMR chemical shift in α-boron nitride based on an analysis of connectivities (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 19 (1998), S. 716-725 
    Details
    ISSN: 0192-8651
    Schlagwort(e): NMR ; boron nitride ; solid state ; theoretical chemistry ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Informatik
    Notizen: Hydrogen-saturated cut-outs of hexagonal boron nitride have been used to model the solid state. Model compounds have been geometry optimized by means of density functional theory, whereas chemical shift calculations have been carried out at the coupled-perturbed Hartree-Fock level of theory employing gauge-including atomic orbital (GIAO) basis sets. The reliability of results has been tested against experimental values for chemical shifts in stable molecules with similar structural elements. With increasing cluster size, viz. a vanishing influence of the saturating hydrogens on the innermost nitrogen atoms, we find a convergence of 15N chemical shifts. A classification scheme for the chemical environment of a nitrogen atom has been set up according to its bonding graph including the second coordination sphere. For a given connectivity, chemical shifts vary within a few parts per million, thus enabling us to predict a 15N-NMR chemical shift of -285 ± 5 ppm for solid α-boron nitride.   © 1998 John Wiley & Sons, Inc.   J Comput Chem 19: 716-725, 1998
    Zusätzliches Material: 6 Ill.
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  • 92
    Digitale Medien
    Digitale Medien
    Determination of molecular weight distributions of novolac resins by gel permeation chromatography (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 35 (1997), S. 1399-1407 
    Details
    ISSN: 0887-624X
    Schlagwort(e): phenol-formaldehyde resin; ; novolac ; GPC ; molecular weight averages ; NMR ; hydrodynamic volume ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The number- and weight-average molecular weights of several statistical and high ortho novolac resins were determined using gel permeation chromatography (GPC). The standards used were pure compounds having between 2 and 12 phenol units bridged via methylene linkages. Three series of compounds were studied: (i) those with methylene linkages substituted in only the ortho positions relative to the phenolic hydroxyl group; (ii) those in which all para positions, together with sufficient ortho positions, were used to synthesize the compounds; and (iii) those in which the methylene linkages were substituted at a mixture of ortho and para positions. Such compounds, having known molecular architecture and units similar to the segments of industrial novolac resins, provide for a more exact measurement of the molecular weight than do the commonly used poly(styrene) standards. Using these new standards the number average molecular weights of the resins determined by GPC were in good agreement with the average molecular weight obtained by 1H-NMR spectra of the resins, particularly for low molecular weight resins. GPC analysis of higher molecular weight resins tends to underestimate the molecular weights because of complications introduced by hydrogen bonding. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1399-1407, 1997
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  • 93
    Digitale Medien
    Digitale Medien
    Chemistry of novolac resins. II. Reaction of model phenols with hexamethylenetetramine (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 35 (1997), S. 1389-1398 
    Details
    ISSN: 0887-624X
    Schlagwort(e): benzylamines ; benzoxazines ; curving ; HMTA ; NMR ; novolac resins ; xylenols ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: It is proposed that the reactions of hexamethylenetetramine (HMTA) with 2,4-xylenol and with 2,6-xylenol occur by different pathways. The rate of reaction and the final product distribution depend on the initial xylenol : HMTA ratio and are different in the two systems. Measured by HMTA consumption, with 2,4-xylenol the reaction rate increased with increasing xylenol : HMTA ratios, whereas with 2,6-xylenol the rate of reaction decreased with increasing 2,6-xylenol : HMTA ratio. In systems which contain both 2,4- and 2,6-xylenol, a strong preference for reaction of the HMTA with the ortho site of 2,4-xylenol was noted. This preference was apparent even in mixtures in which 2,6-xylenol was present in greater amounts than 2,4-xylenol. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1389-1398, 1997
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  • 94
    Digitale Medien
    Digitale Medien
    Influence of the stoichiometry of epoxy-cyanate systems (non-catalyzed and catalyzed) on molten state reactivity (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 35 (1997), S. 3101-3115 
    Details
    ISSN: 0887-624X
    Schlagwort(e): molten state reactivity cyanate esters ; epoxy resins ; NMR ; 13C (liquid and solid) ; FTIR ; DSC ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Based on an FT-IR and 13C-NMR spectroscopic study using model compounds, we previously proposed an epoxy-cyanate coreaction path in the molten state, by identifying all chemical species and their role in the reaction mixture. These data were then applied to difunctional systems involving diglycidyl ether of bisphenol A (DGEBA) and bisphenol A dicyanate (BADCy), with mixtures prepared in different epoxy/cyanate ratios. Using FT-IR and solid state 13C-NMR spectroscopic analyses, we show the effect of epoxy group concentration on the final structure of the system. We were able to show that epoxy functions react on the triazine rings formed in the first step of homopolymerization of cyanates, and that the structure of the final system depends on their initial concentration. In addition, a study of difunctional systems for identical cyanate-epoxy stoichiometry was undertaken in the presence of anionic (imidazole) and metallic (AcAcCu and AcAcCr) catalysts in order to determine their effect on the reactivity of the two monomers and on the structure of the final system. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 3101-3115, 1997
    Zusätzliches Material: 13 Ill.
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  • 95
    Digitale Medien
    Digitale Medien
    NMR study of the structure and properties of poly(MMA-co-VP) crosslinked hydrogels (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 35 (1997), S. 3619-3625 
    Details
    ISSN: 0887-624X
    Schlagwort(e): NMR ; structure ; porperties ; poly(MMA-co-VP) ; hydrogels ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: 1H- and 13C-NMR techniques were used to study the microscopic structure of NMA/VP copolymer hydrogels. Evidence was obtained for a plasticization effect of MMA chains by VP. An original 1H-NMR approach revealed the existence of several types of water with various degree of bounding to the polymer network, a conclusion that is corroborated by a complementary 13C-NMR study. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 3619-3625, 1997
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  • 96
    Digitale Medien
    Digitale Medien
    Novel emulsion graft copolymerization onto the silylmethyl group of poly(dimethylsiloxane) (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 35 (1997), S. 2607-2617 
    Details
    ISSN: 0887-624X
    Schlagwort(e): poly(dimethylsiloxane) ; emulsion graft copolymerization ; hydrogen abstraction reaction ; peroxide ; NMR ; lubricity ; MOPAC ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The influence of radical initiators upon the emulsion graft copolymerization of styrene and acrylonitrile onto poly(dimethylsiloxane) (PDMS) was studied. As initiators, a series of peroxides and hydroperoxides were coupled with ferrous sulfate, among which the tert-butyl peroxylaurate system gave the highest grafting efficiency (30%). The tert-butyl peroxylaurate initiator fulfills the criteria for efficient radical grafting by generating only the tert-butoxy radical, which is reluctant to form a carbon radical via β-scission, being highly hydrophobic, and not carrying a tertiary hydrogen that may be abstracted by a radical. 13C-NMR analysis of the products showed that the grafting occurred on the silylmethyl groups of PDMS to give 10-25 grafts per polymer and graft ratio in the range 44-140%. The PDMS graft copolymers thus obtained could be used as surface-modifying agents to improve the lubricity and water-repellency of ABS [poly(styrene-co-acrylonitrile)-graft-polybutadiene]. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 2607-2617, 1997
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  • 97
    Digitale Medien
    Digitale Medien
    Aggregation kinetics and precipitation phenomena in poly(phenylisocyanide) (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 35 (1997), S. 439-446 
    Details
    ISSN: 0887-624X
    Schlagwort(e): poly(phenylisocyanide) ; NMR ; GPC ; light-scattering techniques ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The preparation of N-phenyl-substituted poly(isocyanide) (N-φ-PIM) utilizing a Ni(II) catalyst in methanol yields a brown material having a number average molecular weight of about 2000. Analysis of this “as prepared” polymer indicates that a rigid rod structure is present in the derived solid. Dissolution of this “as prepared” N-φ-PIM in halocarbon solvents or THF apparently leads to unraveling of the helical polymer with subsequent aggregation and precipitation of materials that have different properties from the original. These processes have been investigated by NMR, GPC, and light-scattering techniques in THF and other solvents. UV spectroscopy has been utilized to follow the kinetics of the aggregation process in solution. X-ray diffraction (XRD) measurements have been employed to investigate the changes attendant with precipitation. An explanation of these observations is offered that implicates the uncoiling of the rigid rod helix as the most important step in defining subsequent physical and chemical properties of the ultimate amorphous polymer. © 1997 John Wiley & Sons, Inc.
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  • 98
    Digitale Medien
    Digitale Medien
    Allyl endcapped polyethylene oxide crosslinkers and their use in superabsorbents (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 35 (1997), S. 799-806 
    Details
    ISSN: 0887-624X
    Schlagwort(e): allyl crosslinkers ; poly(acrylic acid) ; NMR ; superabsorbent ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Several new crosslinkers have been synthesized for evaluation in superabsorbent polymers. These crosslinkers are allyl endcapped polyethylene glycols (PEG) of 200, 600, and 3400 molecular weight. A branched polyethylene oxide of 600 molecular weight, initiated with glycerin, was also synthesized as a trifunctional crosslinker. The allyl functionality was chosen because it is less reactive during radical polymerization than acrylate crosslinkers, an attribute that was necessary to achieve a more uniform gel network. A synthesis route was devised to make the crosslinkers in high purity and yield. The purity of the crosslinkers was determined by 13C NMR, liquid chromatography, and size exclusion chromatography. Gels that were produced with the allyl crosslinkers gave excellent soluble polymer levels and swelling characteristics. The mechanism of incorporation of the allyl functionality was determined to be exclusively vinyl polymerization rather than through hydrogen abstraction. This was determined using NMR spectroscopy, monitoring the polymerization of a model system consisting of acrylic acid and allylacetate. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 799-806, 1997
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  • 99
    Digitale Medien
    Digitale Medien
    Identifying crosslinks in polyethylene following gamma-irradiation in acetylene: A model compound study (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 35 (1997), S. 1549-1562 
    Details
    ISSN: 0887-624X
    Schlagwort(e): polyethylene ; γ-irradiation ; crosslinking ; NMR ; alkanes ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Long-chain linear alkanes have been used as model compounds for polyethylene in an attempt to identify the chemical nature of crosslinks formed in polyethylene when it undergoes γ-irradiation in the presence of acetylene. IR and UV spectral analysis of alkanes and polyethylene following acetylene-sensitized irradiation shows the formation of vinyl, trans-vinylene, and diene groups. A correlation of the conditions of formation suggests that in polyethylene the vinyl groups are restricted to amorphous regions, diene groups are restricted to the crystalline regions, and trans-vinylene groups are formed in both regions. There is no information on the nature of crosslinks. 13C-NMR analysis of alkanes following irradiation of molten alkanes in the presence of 13C-enriched acetylene has shown that a range of saturated alphatic structures are formed by inclusion of acetylene molecules in the alkane structure. They include ethyl branches, γ-branches,—CH(CH3)—, and —CH2—CH2— branches as the major species; the latter two are potential crosslink sites in the irradiation of polyethylene. In addition, the NMR analysis confirmed that the C atoms of the vinyl groups come from acetylene molecules and those of the trans-vinylene groups come from alkane molecules. Data on irradiation of the alkanes in the crystalline state showed that acetylene inclusion in the alkane structure is minimal under these conditions. The principal finding of this work is that acetylene can be incorporated as saturated aliphatic crosslinks in the amorphous regions of polyethylene during high-energy irradiation. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1549-1561, 1997
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    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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    Artikel (Nationallizenzen)
  • 100
    Digitale Medien
    Digitale Medien
    O-nitromandelic acid: A chiral solvating agent for the NMR determination of chiral diamine enantiomeric purity (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 9 (1997), S. 556-562 
    Details
    ISSN: 0899-0042
    Schlagwort(e): O-nitromandelic acid ; chiral solvating agent ; NMR ; enantiomeric purity ; mandelic acid ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: O-Nitromandelic acid, easily prepared from either enantiomer of mandelic acid, has been used as a chiral solvating agent for the determination of enantiomeric purity of several diamine derivatives and other compounds using 1H NMR spectroscopy. Chirality 9:556-562, 1997. © 1997 Wiley-Liss, Inc.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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    Artikel (Nationallizenzen)
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