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  • 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology  (6)
  • JSTOR Archive Collection Business II  (3)
  • Course of study: MSc Biological Oceanography
  • Wiley  (7)
  • SEISMOLOGICAL SOC AMER  (3)
Collection
Years
  • 1
    Publication Date: 2023-02-08
    Description: We use observations from novel biogeochemical profiling floats deployed by the Southern Ocean Carbon and Climate Observations and Modeling program to estimate annual net community production (ANCP; associated with carbon export) from the seasonal drawdown of mesopelagic oxygen and surface nitrate in the Southern Ocean. Our estimates agree with previous observations in showing an increase in ANCP in the vicinity of the polar front (∼3 mol C m−2 y−1), compared to lower rates in the subtropical zone (≤ 1 mol C m−2 y−1) and the seasonal ice zone (〈2 mol C m−2 y−1). Paradoxically, the increase in ANCP south of the subtropical front is associated with elevated surface nitrate and silicate concentrations, but decreasing surface iron. We hypothesize that iron limitation promotes silicification in diatoms, which is evidenced by the low silicate to nitrate ratio of surface waters around the Antarctic polar front. High diatom silicification increases the ballasting effect of particulate organic carbon and overall ANCP in this region. A model-based assessment of our methods shows a good agreement between ANCP estimates based on oxygen and nitrate drawdown and the modeled downward organic carbon flux at 100 m. This agreement supports the presumption that net biological consumption is the dominant process affecting the drawdown of these chemical tracers and that, given sufficient data, ANCP can be inferred from observations of oxygen and/or nitrate drawdown in the Southern Ocean.
    Keywords: Course of study: MSc Biological Oceanography
    Type: Article , PeerReviewed
    Format: text
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  • 2
    Publication Date: 2017-04-04
    Description: We present the first application of a time reverse location method in a volcanic setting, for a family of long-period (LP) events recorded on Mt Etna. Results are compared with locations determined using a full moment tensor grid search inversion and cross-correlation method. From 2008 June 18 to July 3, 50 broad-band seismic stations were deployed on Mt Etna, Italy, in close proximity to the summit. Two families of LP events were detected with dominant spectral peaks around 0.9 Hz. The large number of stations close to the summit allowed us to locate all events in both families using a time reversal location method. The method involves taking the seismic signal, reversing it in time, and using it as a seismic source in a numerical seismic wave simulator where the reversed signals propagate through the numerical model, interfere constructively and destructively, and focus on the original source location. The source location is the computational cell with the largest displacement magnitude at the time of maximum energy current density inside the grid. Before we located the two LP families we first applied the method to two synthetic data sets and found a good fit between the time reverse location and true synthetic location for a known velocity model. The time reverse location results of the two families show a shallow seismic region close to the summit in agreement with the locations using a moment tensor full waveform inversion method and a cross-correlation location method.
    Description: Published
    Description: 452-462
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Volcano seismology ; Computational seismology ; Wave propagation ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 3
    Publication Date: 2017-04-04
    Description: We present the first application of a time reverse location method in a volcanic setting, for a family of long-period (LP) events recorded on Mt Etna. Results are compared with locations determined using a full moment tensor grid search inversion and cross-correlation method. From 2008 June 18 to July 3, 50 broad-band seismic stations were deployed on Mt Etna, Italy, in close proximity to the summit. Two families of LP events were detected with dominant spectral peaks around 0.9 Hz. The large number of stations close to the summit allowed us to locate all events in both families using a time reversal location method. The method involves taking the seismic signal, reversing it in time, and using it as a seismic source in a numerical seismic wave simulator where the reversed signals propagate through the numerical model, interfere constructively and destructively, and focus on the original source location. The source location is the computational cell with the largest displacement magnitude at the time of maximum energy current density inside the grid. Before we located the two LP families we first applied the method to two synthetic data sets and found a good fit between the time reverse location and true synthetic location for a known velocity model. The time reverse location results of the two families show a shallow seismic region close to the summit in agreement with the locations using a moment tensor full waveform inversion method and a cross-correlation location method.
    Description: In press
    Description: (11)
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Volcano seismology ; Computational seismology ; Wave propagation ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 4
    Publication Date: 2020-11-30
    Description: Mt. Vesuvius (southern Italy) is one of the volcanoes that poses the greatest risk in the world because of its highly explosive eruptive style and its proximity to densely populated areas. The urbanization around Mt. Vesuvius began in ancient times, and the impact of eruptions on human activities has been severe. This is testified to by the ruins of Pompeii, which are covered by the products of the plinian eruption that took place in A.D. 79 (Sigurdsson et al. 1985), and more recently by the published reports of the eruptions that occurred from 1631 to 1944. For these reasons, Mt. Vesuvius was also one of the first volcanoes to be equipped with monitoring instruments. Pioneering instrumental observations began just before the second half of the 1800s, when the Vesuvius Observatory was founded in 1841 (Imbò 1949). At that time, Vesuvius was very active (Ricciardi 2009), and its effusive and explosive eruptions often caused damage to the surrounding areas. At the same time, it was a famous tourist attraction that drew travelers from all over the world (Gasparini and Musella 1991). Since the middle of the 1800s, at least 12 eruptions have occurred that have been superimposed on persistent intra-crater activity that has been characterized by Strombolian explosions and by the formation of small lava lakes. The last eruption occurred on 18 March 1944 and marked a change in the status of Mt. Vesuvius, as it entered a closed-conduit phase that persists today. Following this last eruption, a change occurred in the 1960s, as documented by an increase in the occurrence rate of earthquakes. Since 1972, the monitoring of Mt. Vesuvius has improved over time and become more systematic, so that there is a remarkable dataset relating to the current phase of quiescence. Over more than a century and a half of observations, many monitoring instruments have been used for Mt. Vesuvius, including early seismometers, several of which are now kept in the Museum of Volcanology of the Vesuvius Observatory. The present monitoring system is based on seismological, geodetical geodetical, and geochemical observations performed using an instrumental network that was designed on the basis of the current state of the volcano while also taking into account the likely scenario of future unrest.
    Description: Published
    Description: 625-634
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Seismological Monitoring ; Mount Vesuvius ; 04. Solid Earth::04.06. Seismology::04.06.05. Historical seismology ; 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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  • 5
    Publication Date: 2017-04-04
    Description: Stress can undergo rapid temporal changes in volcanic environments, and this is particularly true during eruptions. We use two independent methods, coda wave interferometry (CWI) and shear wave splitting (SWS) analysis to track stress related wave propagation effects during the waning phase of the 2002 NE fissure eruption at Mt Etna. CWI is used to estimate temporal changes in seismic wave velocity, while SWS is employed to monitor changes in elastic anisotropy. We analyse seismic doublets, detecting temporal changes both in wave velocities and anisotropy, consistent with observed eruptive activity. In particular, syn-eruptive wave propagation changes indicate a depressurization of the system, heralding the termination of the eruption, which occurs three days later.
    Description: Published
    Description: 1779-1788
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Interferometry ; Seismic anisotropy ; Volcano seismology ; Volcano monitoring ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 6
    Publication Date: 2017-04-04
    Description: We propose a method for analyzing the polarization of three-component digital recordings using the discrete wavelet transform (DWT). This method allows for the automatic detection and separation of seismic phases that have a coherent linear or elliptical polarization. It can be correctly used in the analysis of seismic signals relating to volcanic activity because they arise from a complex wave field that consists of near-field and far-field components that have frequency-dependent polarization. First, the analytic extension of the signal is decomposed using DWT, then each single component is used to determine a local complex polarization vector in the timescale domain. This analysis reveals the presence of seismic phases with coherent polarization over a range of DWT scales and finite temporal intervals. Using the orthogonality property of the DWT, it is possible to isolate a single coherent component, reconstructing it in the time domain and computing the full polarization tensor. This procedure can be fully automated, introducing a quantitative definition of wavelet polarization coherence on the DWT dyadic grid. A recursive algorithm (called POLWAV) starts from the wavelet coefficient with the highest modulus, and then selects all of the neighbors that show coherence with it above a given threshold. We show how the POLWAValgorithm can be used for separating wave-field components and for detecting coherent seismic phases on continuous recordings. Example applications to actual seismic recordings at Stromboli Volcano (Tyrrhenian Sea) are presented.
    Description: Published
    Description: 670–683
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Polarization Analysis ; Discrete Wavelet Domain ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 7
    Publication Date: 2017-04-04
    Description: The surface-wave field associated with the explosive activity at Stromboli volcano is investigated using data recorded by two short-period seismic arrays, deployed on the north and west flanks of the volcano. The group-velocity dispersion curves for Rayleigh waves are derived using the multiple filter technique. The phasevelocity dispersion curves are recovered using a phase match filter and compared with that inferred from zero-lag cross-correlation analysis applied to the array data. These analyses indicate Rayleigh-wave group velocities ranging from 0.29 to 0.24 km/sec in the 1.5- to 8.0-Hz frequency band, and phase velocities ranging from 1 km/sec at 1.5 Hz to about 0.3 km/sec at frequencies above 5 Hz. In addition, the dispersive properties of the attenuation coefficient (c) for Rayleigh waves are inferred from application of the multiple filter technique to seismograms recorded at different distances from the source. These results are validated through examination of the spectral amplitude decay with distance for both body and Rayleigh waves. The values of the body-wave quality factor thus obtained are Qa=20 and Qa=6 for the north and west side of the island, respectively. The velocity and attenuation dispersion curves are inverted for the shear-wave velocity and Qb structures down to a depth of about 200 m. Shear-wave velocities for the west flank range from about 0.3 km/ sec for the uppermost 17-m-thick layer to 1.9 km/sec at depths greater than 200 m. Comparison with previous studies indicates a similar velocity structure for the north and west flanks. The attenuation structure for the west flank is described by a shallower, 36-m-thick layer with Qb=9, underlain by a half-space with Qb=50. On the north flank, Qb=40 for the shallower 30-m-thick layer and Qb=44 for the underlying half-space. Residuals from analysis of the spectral decay with distance are used to quantify site effects affecting the different array elements on the west flank. Local amplifications at that array are interpreted in terms of an edge effect associated with concave topography. Velocity similarities observed at the north and west flanks are compatible with surface geologic data. Discrepancies in attenuation properties at the two sites are interpreted in terms of different degrees of heterogeneity and crack density controlling the scattering quality factor Qs.
    Description: Published
    Description: 1102-1116
    Description: JCR Journal
    Description: reserved
    Keywords: Stromboli ; sesimic attenuation ; velocity model ; 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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  • 8
    Journal cover
    Unknown
    Wiley | Financial Management Association International | JSTOR
    Online: 1(1).1972 – (older than 4 years)
    Publisher: Wiley , Financial Management Association International , JSTOR
    Print ISSN: 0046-3892
    Electronic ISSN: 1755-053X
    Topics: Economics
    Keywords: JSTOR Archive Collection Business II
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  • 9
    Journal cover
    Unknown
    Wiley | JSTOR
    Online: 78.1976 – (older than 6 years)
    Publisher: Wiley , JSTOR
    Print ISSN: 0347-0520
    Electronic ISSN: 1467-9442
    Topics: Economics
    Keywords: JSTOR Archive Collection Business II
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  • 10
    Journal cover
    Unknown
    Wiley | JSTOR | formerly Oxford University Press (OUP)
    Online: 10(1).1988 –
    Formerly as: Illinois Agricultural Economics; North Central Journal of Agricultural Economics; Review of Agricultural Economics  (1961–2009)
    Publisher: Wiley , JSTOR , formerly Oxford University Press (OUP)
    Print ISSN: 0191-9016 , 1058-7195 , 2040-5790
    Electronic ISSN: 1467-9353 , 2040-5804
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Economics
    Keywords: JSTOR Archive Collection Business II
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