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  • 1
    Electronic Resource
    Electronic Resource
    Raman studies of NiX2 · 6H2O and FeCl2 · 4H2O (1989)
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 20 (1989), S. 773-777 
    Details
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The Raman spectra of NiCl2 · 6H2O, NiBr2 · 6H2O and FeCl2 · 4H2O single crystals were measured in the range 50-3600 cm-1 at liquid nitrogen temperature. A new assignment of the lattice water translations in the two hexahydrates was made and the metal-halogen stretching mode was identified. A comparison with recent IR data provided a good characterization of the water libration region. Some proposals for discriminating between the lattice water modes and the coordinated water modes are given for the water internal modes (bending and stretching).
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jrs.1250201204
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  • 2
    Electronic Resource
    Electronic Resource
    Raman and infrared spectra of NiI2 · 6H2O (1991)
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 22 (1991), S. 397-401 
    Details
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The polarized Raman spectra and infrared absorption spectra of NiI2 · 6H2O were measured in the 50-4000 cm-1 region at low temperatures. Deuterated samples were also studied and gave results which were useful for interpretation purposes. Satisfactory assignments of water internal and external modes and lattice vibrations were made. The vibrational analysis, on the basis of which the assignments were made, was related to the D34 factor group; however, the symmetry of the Raman-active bands, as deduced from polarized spectra, suggests that for water librations the C2h factor group provides a better basis for interpretation.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jrs.1250220707
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  • 3
    Electronic Resource
    Electronic Resource
    Nitrogen hyperfine splitting of nitroxide solutions: Differently structured and charged nitroxides as probes of environmental properties (1987)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 25 (1987), S. 897-904 
    Details
    ISSN: 0749-1581
    Keywords: Nitroxides ; Nitrogen isotropic coupling constants ; Solvent polarity ; ESR spectra ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The dependence of the nitrogen isotropic coupling constants, aN, on the structure and charge of the radicals, temperature and solvent polarity was analysed for solutions containing the following nitroxides: 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (Tempol); 4-trimethylammonium-2,2,6,6-tetramethylpiperidine-1-oxyl, iodide salt (TempTMA+); 2,2,5,5-tetramethylpyrrolin-1-oxyl-3-carboxamide (Tempyo); and 2,2,5,5-tetramethylpyrrolin-1-oxyl-3-carboxylate, sodium salt (Tempyca-). Polar hydrogen bond acceptor solvents and hydroxylic solvents were used. In each solvent used, Tempol and Tempyca- showed aN values which were higher, respectively, than those of TempTMA+ and Tempyo due to inductive, structural and charge effects. Such effects were analysed on the basis of the proton and 13C coupling constants. Non-hydroxylic solvents gave temperature coefficients for aN that were almost independent of solvent polarity. Lower daN/dT values were found for charged radicals. A gradual decrease of temperature coefficients with decreasing hydrogen bond donor (HBD) properties were related to free volume changes of radical molecules. The analysis of the aN dependence on polarity parameters gave the best fitting using a simplified form of the Wertheim reaction field. Tempyca- was greatly affected by changes in polarity. A parameter to account for HBD abilities was also analysed.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260251014
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  • 4
    Electronic Resource
    Electronic Resource
    Raman and infrared spectra of transition metal halide hexahydrates (1987)
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 18 (1987), S. 485-491 
    Details
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The Raman and infrared spectra of NiCl2·6H2O, NiCl2·6D2O, CoCl2·6H2O, CoCl2·6D2O and CoBr2·6H2O single crystals have been measured in the range 3600-30 cm-1 (Raman) and 3800-400 cm-1 (IR). The water internal modes have been best assigned for NiCl2·6H2O, including Fermi resonance effects. The corresponding Raman intensities have been interpreted in terms of the free molecule Raman tensors. Among the lattice vibrations, the metal halide and metal-water stretchings, and also the librations of the MX2·4H2O octahedra, have been identified and assigned.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jrs.1250180707
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  • 5
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    The April-May 2006 volcano-tectonic events at Stromboli volcano (Southern Italy) and their relation with the magmatic system. (2006)
    Details
    Publication Date: 2020-12-01
    Description: Between April 10th and May 22th 2006, a small seismic swarm of 5 volcano-tectonic events occurred on the volcanic island of Stromboli (Southern Italy). Two of these, having M 〉 3 and an intensity of about V-VI MCS, were clearly felt causing concern in the population. They were recorded during a period of increased explosive activity and were followed by two major explosions at the summit craters on May 22th, few hours after the last earthquake and on 16th June. The location of such events has been performed using a probabilistic approach based on the Equal Differential Time tecnique. Using this tecnique, we were able to locate all the events, showing how they cluster below the volcanic edifice at a depth of about 5÷6 km. From observed P wave polarities we determined the focal mechanisms of the 4 major events. Using earthquake scaling nlaws, we calculated the fault area and the average slip for the two major events. Finally, assuming an homogeneous half-space model we computed the isotropic stress changes below the volcano edifice. The negative stress variation over the central axis of the volcano suggests that the earthquakes were triggered by a pressurization of the magmatic system.
    Description: Published
    Description: open
    Keywords: Stromboli ; Magmatic ; 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
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
    Format: 524511 bytes
    Format: application/pdf
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  • 6
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    Seismological monitoring of the February 2007 effusive eruption of the Stromboli volcano (2008)
    Details
    Publication Date: 2020-11-30
    Description: On February 27, 2007, the Stromboli volcano, which has usually been characterized by moderate explosive activity, started an effusive eruption with a small lava flow down the NW flank. The permanent broadband network installed on the island allowed the revealing of anomalies in the seismicity before the effusive eruption and for the phenomena to be followed over time, thus obtaining meaningful information about the eruption dynamics. During the effusive phase, a major explosion occurred on March 15, 2007. On that occasion, two strainmeters deployed on the volcano in the previous year recorded a strain increment before the blast. After this explosion, which further destabilized the upper part of the edifice, swarms of Long-Period (LP) and hybrid events were recorded. The characteristics and locations of these events suggest that they were associated with the fracturing processes that affected the summit area of the cone. During the effusive phase, changes in the Very Long Period (VLP) event location were recorded. This type of events accompanied the change in the eruptive style, providing information about the magmatic conduit involved in their seismogenetic processes. The effusive phase stopped on April 2, 2007, and the typical Strombolian activity restarted some months later.
    Description: JCR Journal
    Description: open
    Keywords: Stromboli ; volcano monitoring ; volcano seismicity ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 7
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    Unsupervised Neural Analysis of Very-Long-Period Events at Stromboli Volcano Using the Self-Organizing Maps (2008)
    Seismological Society of America
    Details
    Publication Date: 2017-04-04
    Description: We have implemented a method based on an unsupervised neural network to cluster the waveforms of very-long-period (VLP) events associated with explosive activity at the Stromboli volcano (southern Italy). Stromboli has several active vents in the summit area producing together more than 200 explosions=day. We applied this method to investigate the relationship between each vent and its associated VLP explosive waveform. We selected 147 VLP events recorded between November and December 2005, when digital infrared camera recordings were available. From a visual inspection of the infrared camera images, we classified the VLPs on the basis of which vent produced each explosion. We then applied the self-organizing map (SOM), an unsupervised neural technique widely applied in data exploratory analysis, to cluster the VLPs on the basis of their waveform similarity. Our analysis demonstrates that the most recurrent VLP waveforms are usually generated by the same vent. Some exceptions occurred, however, in which different waveforms are associated with the same vent, as well as different vents generating similar waveforms. This suggests that the geometry of the upper conduit-vent system plays a role in shaping the recurring VLP events, whereas occasional modest changes in the source process dynamics produce the observed exceptions.
    Description: Published
    Description: 2449–2459
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Stromboli ; Maps ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 05. General::05.01. Computational geophysics::05.01.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 8
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    Shallow-conduit dynamics at Stromboli Volcano, Italy, imaged from waveform inversions (2008)
    The Geological Society of London
    Details
    Publication Date: 2017-04-04
    Description: Modelling of Very-Long-Period (VLP) seismic data recorded during explosive activity at Stromboli in 1997 provides an image of the uppermost 1 km of its volcanic plumbing system. Two distinct dyke-like conduit structures are identified, each representative of explosive eruptions from two different vents located near the northern and southern perimeters of the summit crater. Observed volumetric changes in the dykes are viewed as the result of a piston-like action of the magma associated with the disruption of a gas slug transiting through discontinuities in the dyke apertures. Accompanying these volumetric source components are single vertical forces resulting from an exchange of linear momentum between the source and the Earth. In the dyke system underlying the northern vent, a primary disruption site is observed at an elevation near 440 m where a bifurcation in the conduit occurs. At a depth of 80 m below sea level, a sharp corner in the conduit marks another location where the elastic response of the solid to the action of the upper source induces pressure and momentum changes in the magma. In the conduit underlying the southern vent, the junction of two inclined dykes with a sub-vertical dyke at 520 m elevation is a primary site of gas slug disruption, and another conduit corner 280 m below sea level represents a coupling location between the elastic response of the solid and fluid motion.
    Description: Published
    Description: 57-84
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: N/A or not JCR
    Description: reserved
    Keywords: Shallow-conduit dynamics ; Stromboli ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 9
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    Automatic detection of landslides at Stromboli using neural network analysis of seismic signals (2012)
    Details
    Publication Date: 2017-04-04
    Description: Landslides along the Sciara del Fuoco flank of Stromboli volcano are generally accompanied by c1istinctive seismic signals which can be used for srudying this phenomenon. These signals are characterìzed by a spectral content with higher frequencies and a wider band than the typical explosion quakes and volcanic tremor signals which are continuously recorded at Stromboli. Furthermore their amplirude envelope usually shows a cigar-like shape. These two fearures make the detection of such signals quite easy. The detection of landslides at Stromboli has shown to be an important shortterm precursor of effusive eruptions. Before the Feb. 27th 2007 eruption, the opening of the effusive vents was preceded by few hours oI increased occurrence of landslide signals (Martini et al., 2007). Furthermore since the Sciara del Fuoco has shown significant instabilities during the 2002-2003 eruption, the automatic detection of landslide signals is an important monitoring tool for notifying variations in the stability of this flank. We propose a technique based on a Multi Layer Perceptron (MLP) neural network which has shown excellent performances. The network is composed of two layer of neurons, the hidden and the output. The hidden layer is composed of 4 neurons while the output layer is composed by a single neuron whose output value ranges between Oand 1, with values higher than a given threshold (e.g. 0.5) meaning positive detection. The continuous seismic signals are analysed using moving windows of 24 s, with an overlap of 12 s. For each of these windows the neural output is computed. The waveforms of each time window are parametrized using both their spectrogram and their amplirude envelope. The spectrogram is described using the Linear Preclictive Cocling (L'PC) technique which allows to represent the spectral content using a limited number of coefficients. The whole signal is c1ivided into 8 sub-windows of 5.12 s length, with an overlapping of 2.56 s. For each sub-window we compute 6 LPC coefficients, so each spectrogram is described by only 48 coefficients. The amplirude envelope is defined by computing the c1ifference between the maximum and minimum value over 1 s sub-windows obtaining 24 coefficients. In conclusion we use an input vector composed of 72 elements (48+24). This vector has shown to be an efficient and compact representation of the raw signal (composed of 1200 samples) (Esposito et al. 2006). The dataset used for determining the network parameters is composed of 537 signals, c1ivided in two classes: 267 landslide signals and 270 other signals (explosions and tremor). The classification of these signals has been performed by analysts. The training is carried out using subsets of 5/8 of the total dataset. The testing subsets are composed by the remaining 3/8. The network has shown a performance of about 98.7%. This value is an average over 6 random permutations of the dataset. A preliminary real-rime automatic system has already been implemented. This system performs continuous analysis of the seismic signals, publishing them on internal web pages. It allows a detection of the landslides and a comparison with the past activity on arbitrary rime intervals.
    Description: Published
    Description: Nicolosi (Catania)
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: 3.1. Fisica dei terremoti
    Description: 3.6. Fisica del vulcanismo
    Description: open
    Keywords: Automatic detection ; landslides ; Stromboli ; neural network analysis ; seismic signals ; 04. Solid Earth::04.02. Exploration geophysics::04.02.99. General or miscellaneous ; 04. Solid Earth::04.02. Exploration geophysics::04.02.06. Seismic methods ; 04. Solid Earth::04.02. Exploration geophysics::04.02.07. Instruments and techniques ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Conference paper
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  • 10
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    Seismological Insight on the Shallow Magma System (2012)
    AGU
    Details
    Publication Date: 2017-04-04
    Description: We present an overview of the volcanic seismicity recorded at Stromboli from January to September 2003. The data set starts few weeks after the onset of the eruption and covers most of the effusive phase and the subsequent recovery of the explosive activity. The most important variations occurred between May and July coinciding with the waning of the lava flow and the reappearance of Strombolian activity at the summit craters. All the parameters indicate that the shallow magmatic system has not undergone permanent changes during this period. The only significant variation related to the shallow conduit is the increase in volcanic tremor amplitude and the change in the spectral content of long-period events during the transition between effusive and explosive activity. A slight increase in the very-long-period (VLP) events source elevation seems to mark the rise of the magma at the end of the effusive phase. The variations in the VLP events occurrence rate are more likely to be attributed to changes in the gas flow rate and the bubble coalescence mechanism, therefore, to a deeper portion of the magmatic system. The 5 April paroxysm is associated only with a small increase of the activity in the following days.
    Description: Published
    Description: 279-286
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: reserved
    Keywords: Stromboli ; Seismological monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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