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  • 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring  (4)
  • 01. Atmosphere::01.02. Ionosphere::01.02.05. Wave propagation  (3)
  • Apennines
  • Elsevier Science Limited  (8)
  • Blackwell Publishing Ltd
  • Elsevier
  • 2010-2014  (8)
  • 1990-1994
  • 1980-1984
  • 1925-1929
  • 2014  (8)
Collection
Years
  • 2010-2014  (8)
  • 1990-1994
  • 1980-1984
  • 1925-1929
Year
  • 1
    Publication Date: 2021-07-14
    Description: We present the first density model of Stromboli volcano (Aeolian Islands, Italy) obtained by simultaneously inverting land-based (543) and sea-surface (327) relative gravity data. Modern positioning technology, a 1 × 1 m digital elevation model, and a 15 × 15m bathymetric model made it possible to obtain a detailed 3-D density model through an iteratively reweighted smoothness-constrained least-squares inversion that explained the land-based gravity data to 0.09 mGal and the sea-surface data to 5 mGal. Our inverse formulation avoids introducing any assumptions about density magnitudes. At 125 m depth from the land surface, the inferred mean density of the island is 2380 kg m−3, with corresponding 2.5 and 97.5 percentiles of 2200 and 2530 kg m−3. This density range covers the rock densities of new and previously published samples of Paleostromboli I, Vancori, Neostromboli and San Bartolo lava flows. High-density anomalies in the central and southern part of the island can be related to two main degassing faults crossing the island (N41 and N64) that are interpreted as preferential regions of dyke intrusions. In addition, two low-density anomalies are found in the northeastern part and in the summit area of the island. These anomalies seem to be geographically related with past paroxysmal explosive phreato-magmatic events that have played important roles in the evolution of Stromboli Island by forming the Scari caldera and the Neostromboli crater, respectively. © 2014 Elsevier B.V. All rights reserved.
    Description: Published
    Description: 58–69
    Description: 3V. Dinamiche e scenari eruttivi
    Description: JCR Journal
    Description: restricted
    Keywords: Stromboli, Gravity, Inversion, Geophysics ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
    Publication Date: 2017-04-04
    Description: The main goal of this study is to provide moment tensor solutions for small and moderate earthquakes of the Matese seismic sequence in southern Italy for the period of December 2013–January 2014. We estimate the focal mechanisms of 31 earthquakes with local magnitudes related to the Matese earthquake seismic sequence (December 2013–January 2014) in Southern-Central Italy which are recorded by the broadband stations of the Italian National Seismic Network and the Mediterranean Very Broadband Seismographic Network (MedNet) run by the Istituto Nazionale di Geofisica e Vulcanologia (INGV). The solutions show that normal faulting is the prevailing style of seismic deformation in agreement with the local faults mapped outin the area. Comparisons with already published solutions and with seismological and geological information available allowed us to properly interpret the moment tensor solutions in the frame of the seismic sequence evolution and also to furnish additional information about less energetic seismic phases. Focal data were inverted to obtain the seismogenic stress in the study area. The results are compatible with the major tectonic domain of the area.
    Description: Published
    Description: 118-124
    Description: 2T. Tettonica attiva
    Description: JCR Journal
    Description: restricted
    Keywords: Moment tensors ; Southern Italy ; Apennines ; Stress inversion ; Seismicity and tectonics ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 3
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    Elsevier Science Limited
    Publication Date: 2017-04-04
    Description: New outcomes are proposed for ionospheric absorption starting from the Appleton-Hartree formula, in its complete form. The range of applicability is discussed for the approximate formulae, which are usually employed in the calculation of non-deviative absorption coefficient. These results were achieved by performing a more refined approximation that is valid under quasi-longitudinal (QL) propagation conditions. The more refined QL approximation and the usually employed non-deviative absorption are compared with that derived from a complete formulation. Their expressions, nothing complicated, can usefully be implemented in a software program running on modern computers. Moreover, the importance of considering Booker’s rule is highlighted. A radio link of ground range D = 1000 km was also simulated using ray tracing for a sample daytime ionosphere. Finally, some estimations of the integrated absorption for the radio link considered are provided for different frequencies.
    Description: Published
    Description: 1642-1650
    Description: 2A. Fisica dell'alta atmosfera
    Description: JCR Journal
    Description: open
    Keywords: Appleton-Hartree formula ; more refined quasi-longitudinal approximation ; usually employed non-deviative absorption ; Booker’s rule ; 01. Atmosphere::01.02. Ionosphere::01.02.99. General or miscellaneous ; 01. Atmosphere::01.02. Ionosphere::01.02.01. Ion chemistry and composition ; 01. Atmosphere::01.02. Ionosphere::01.02.04. Plasma Physics ; 01. Atmosphere::01.02. Ionosphere::01.02.05. Wave propagation ; 05. General::05.01. Computational geophysics::05.01.99. General or miscellaneous ; 05. General::05.01. Computational geophysics::05.01.05. Algorithms and implementation ; 05. General::05.05. Mathematical geophysics::05.05.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 4
    Publication Date: 2017-04-04
    Description: This paper is focused on unusual nighttime impulsive electron density enhancements that are rarely observed at low latitudes on a wide region of South America, under quiet and medium/high geomagnetic conditions. The phenomenon under investigation is very peculiar because besides being of brief duration, it is characterized by a pronounced compression of the ionosphere. The phenomenon was studied and analyzed using both the F2 layer critical frequency (foF2) and the virtual height of the base of the F region (h'F) values recorded at five ionospheric stations widely distributed in space, namely: Jicamarca (-12.0°, -76.8°, magnetic latitude -2.0°), Peru; Sao Luis (-2.6°, -44.2°, magnetic latitude +6.2°), Cachoeira Paulista (-22.4°, -44.6°, magnetic latitude -13.4°), and Sao Jose´ dos Campos (-23.2°, -45.9°, magnetic latitude -14.1°), Brazil; Tucumán (-26.9°, -65.4°, magnetic latitude -16.8°), Argentina. In a more restricted region over Tucumán, the phenomenon was also investigated by the total electron content (TEC) maps computed by using measurements from 12 GPS receivers. A detailed analysis of isoheight ionosonde plots suggests that traveling ionospheric disturbances (TIDs) caused by gravity wave (GW) propagation could play a significant role in causing the phenomenon both for quiet and for medium/high geomagnetic activity; in the latter case however a recharging of the fountain effect, due to electric fields penetrating from the magnetosphere, joins the TID propagation and plays an as much significant role in causing impulsive electron density enhancements.
    Description: Published
    Description: 369-384
    Description: 2A. Fisica dell'alta atmosfera
    Description: 1IT. Reti di monitoraggio e Osservazioni
    Description: 4IT. Banche dati
    Description: JCR Journal
    Description: restricted
    Keywords: Equatorial ionosphere ; Electron density enhancement ; Traveling ionospheric disturbance ; Fountain effect ; TEC ; 01. Atmosphere::01.02. Ionosphere::01.02.99. General or miscellaneous ; 01. Atmosphere::01.02. Ionosphere::01.02.02. Dynamics ; 01. Atmosphere::01.02. Ionosphere::01.02.05. Wave propagation ; 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques ; 01. Atmosphere::01.03. Magnetosphere::01.03.02. Magnetic storms ; 05. General::05.01. Computational geophysics::05.01.99. General or miscellaneous ; 05. General::05.01. Computational geophysics::05.01.01. Data processing ; 05. General::05.01. Computational geophysics::05.01.03. Inverse methods ; 05. General::05.07. Space and Planetary sciences::05.07.01. Solar-terrestrial interaction ; 05. General::05.07. Space and Planetary sciences::05.07.02. Space weather
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 5
    Publication Date: 2017-04-04
    Description: The present paper proposes to discuss the ionospheric absorption, assuming a quasi-flat layered ionospheric medium, with small horizontal gradients. A recent complex eikonal model [Settimi et al., 2013b] is applied, useful to calculate the absorption due to the ionospheric D-layer, which can be approximately characterized by a linearized analytical profile of complex refractive index, covering a short range of heights between h1= 50 km and h2= 90 km. Moreover, Settimi et al. [2013c] have already compared the complex eikonal model for the D-layer with the analytical Chapman’s profile of ionospheric electron density; the corresponding absorption coefficient is more accurate than Rawer’s theory [1976] in the range of middle critical frequencies. Finally, in this paper, the simple complex eikonal equations, in quasi-longitudinal (QL) approximation, for calculating the non-deviative absorption coefficient due to the propagation across the D-layer are encoded into a so called COMPLEIK (COMPLex EIKonal) subroutine of the IONORT (IONOspheric Ray-Tracing) program [Azzarone et al., 2012]. The IONORT program, which simulates the three-dimensional (3-D) ray-tracing for high frequencies (HF) waves in the ionosphere, runs on the assimilative ISP (IRI-SIRMUP-P) discrete model over the Mediterranean area [Pezzopane et al., 2011]. As main outcome of the paper, the simple COMPLEIK algorithm is compared to the more elaborate semi-empirical ICEPAC formula [Stewart, undated], which refers to various phenomenological parameters such as the critical frequency of E-layer. COMPLEIK is reliable just like the ICEPAC, with the advantage of being implemented more directly. Indeed, the complex eikonal model depends just on some parameters of the electron density profile, which are numerically calculable, such as the maximum height.
    Description: Published
    Description: 201-218
    Description: 2A. Fisica dell'alta atmosfera
    Description: JCR Journal
    Description: partially_open
    Keywords: Ionospheric D-layer ; Quasi-Longitudinal propagation ; non-deviative absorption ; ICEPAC formula ; ISP-IONORT ; Complex Eikonal theory ; 01. Atmosphere::01.02. Ionosphere::01.02.99. General or miscellaneous ; 01. Atmosphere::01.02. Ionosphere::01.02.01. Ion chemistry and composition ; 01. Atmosphere::01.02. Ionosphere::01.02.04. Plasma Physics ; 01. Atmosphere::01.02. Ionosphere::01.02.05. Wave propagation ; 05. General::05.05. Mathematical geophysics::05.05.99. General or miscellaneous ; 05. General::05.07. Space and Planetary sciences::05.07.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 6
    Publication Date: 2017-04-04
    Description: We present a review of our work on data acquired by GEOSTAR-class (GEophysical and Oceanographic STation for Abyssal Research) observatories deployed at three EMSO (European Multidisciplinary Seafloor and water-column Observatory; http://www.emso-eu.org) sites in southern European waters where strong geo-hazards are present: the Western Iberian Margin, the Western Ionian Sea, the Marmara Sea, and the Marsili basin in the Tyrrhenian Sea. A procedure for multiparameter data quality control is described. Then we explain why the seafloor is an interesting observation point for geophysical parameters and how it differs from land sites. We consider four interesting geophysical phenomena found at the EMSO sites that are related to geo-hazard. In the first case, we show how unknown seismicity and landslides in the Western Ionian Sea were identified and roughly localised through a single-sensor analysis based on the seismometer. In the second case, we concentrate on the problem of near-coast tsunami generation and describe a Tsunami Early Warning Detection (TEWD) system, tested in the Western Iberian Margin and currently operating in real time at the Western Ionian site. In the third case, we consider two large volcanoes in the central Mediterranean area, Mt. Etna and the Marsili seamount. Signals from the seismometer and gravimeter recorded at the seafloor at 2100 m b.s.l. show various phases of Mt. Etna's 2002–2003 eruption. For the less-known Marsili we illustrate how several indicators coming from different sensors point to hydrothermal activity. A vector magnetometer at the two volcanic sites helps identify the magnetic lithospheric depth. In the fourth and final case, we present a multiparameter analysis which was focused on finding possible correlations between methane seepage and seismic energy release in the Gulf of Izmit (Marmara Sea).
    Description: Published
    Description: 12–30
    Description: 1A. Geomagnetismo e Paleomagnetismo
    Description: 6A. Monitoraggio ambientale, sicurezza e territorio
    Description: JCR Journal
    Description: restricted
    Keywords: European Seas ; Geophysical measurements ; Multiparameter seafloor and water-column observatories ; Data quality analysis ; Geo-hazard ; Tsunami early detection ; 04. Solid Earth::04.05. Geomagnetism::04.05.04. Magnetic anomalies ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 7
    Publication Date: 2017-04-04
    Description: The shallow thermal aquifer at Vulcano Island is strongly affected by deep volcanic fluids. The most significant variations were observed during the 1989–1996 crisis due to a large input of steam and acidic gases from depth. Besides chemical variations related to the input of deep fluids, the record of the water-table elevation at monitored wells has provided remarkable insights into the pressure conditions of the volcano-hydrothermal system. After the pressure drop due to the extensive vaporization of the hydrothermal aquifer, occurred after 1993, the volcano-hydrothermal system has been re-pressurized since 2001, probably because of the contribution of volatiles from the hydrothermal-magmatic source. The increase in fluid pressure may have caused reopening of fractures (which had self-seated during the previous period of cooling) and the onset of a phase of higher vapor output in the fumarole field later in 2004. The fracture opening would have promoted further vapor separation from the deep fluid reservoir (hypothesized at 0.5–1.5 km depth) and finally the drainage of S-rich fluids into the shallow thermal aquifer (found out at few tens of meters of depth). The monitoring of both the water chemistry and the water-table elevation provides insights into the eventual pressurization of the volcano-hydrothermal system that precedes the fracture opening and the extensive drainage of deep fluids. The findings of this study could represent crucial information about the stability of the volcano edifice, and lead to reliable techniques for determining the risk of or even predicting phreatic explosions.
    Description: Published
    Description: 70-80
    Description: 5V. Sorveglianza vulcanica ed emergenze
    Description: JCR Journal
    Description: restricted
    Keywords: Hydrothermal system ; Vulcano Island ; Fluid pressure ; Thermal wells ; 03. Hydrosphere::03.02. Hydrology::03.02.03. Groundwater processes ; 03. Hydrosphere::03.04. Chemical and biological::03.04.06. Hydrothermal systems ; 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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  • 8
    Publication Date: 2021-12-13
    Description: Volcanic lake research boosted after lethal gas burst occurred at Lake Nyos (Cameroon) in 1986, a limnic rather than a volcanic event. This led to the foundation of the IAVCEI-Commission on Volcanic Lakes, which grew out into a multi-disciplinary scientific community since the 1990s. We here introduce the first data base of volcanic lakes VOLADA, containing 474 lakes, a number that, in our opinion, is surprisingly high. VOLADA could become an interactive, open-access working tool where our community can rely on in the future. Many of the compiled lakes were almost unknown, or at least unstudied to date, whereas there are acidic crater lakes topping active magmat- ic–hydrothermal systems that are continuously or discontinuously monitored, providing useful information for volcanic surveillance (e.g., Ruapehu, Yugama, Poás). Nyos-type lakes, i.e. those hosted in quiescent volcanoes and characterized by significant gas accumulation in bottom waters, are potentially hazardous. These lakes tend to remain stably stratified in tropical and sub-tropical climates (meromictic), leading to long-term build- up of gas, which can be released after a trigger. Some of the unstudied lakes are possibly in the latter situation. Acidic crater lakes are easily recognized as active, whereas Nyos-type lakes can only be recognized as potentially hazardous if bottom waters are investigated, a less obvious operation. In this review, research strategies are lined out, especially for the “active crater lakes”. We make suggestions for monitoring frequency based on the principle of the “residence time dependent monitoring time window”. A complementary, multi-disciplinary (geochemis- try, geophysics, limnology, statistics) approach is considered to provide new ideas, which can be the bases for fu- ture volcanic lake monitoring. More profound deterministic knowledge (e.g., precursory signals for phreatic eruptions, or lake roll-over events) should not only serve to enhance conceptual models of single lakes, but also serve as input parameters in probabilistic approaches. After more than 25 years of pioneering studies on rather few lakes (~20% of all), the scientific community should be challenged to study the many poorly studied volcanic lakes, in order to better constrain the related hazards.
    Description: Published
    Description: 78-97
    Description: 2V. Dinamiche di unrest e scenari pre-eruttivi
    Description: JCR Journal
    Description: restricted
    Keywords: Volcanic lakes ; Active crater lakes ; Nyos-type lakes ; Monitoring ; Residence time dependent monitoring time window ; Hazard forecasting ; VOLADA data base ; 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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