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  • Springer Nature  (88,456)
  • American Geophysical Union  (26,228)
  • Periodicals Archive Online (PAO)  (20,654)
  • Nature Publishing Group  (17,612)
  • AGU
  • AGU (American Geological Union)
  • American Meteorological Society
  • 2020-2022  (85,071)
  • 1980-1984  (76,141)
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  • 1
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    Millimeter wave spectroscopic measurements over the South Pole: 5. Morphology and evolution of HNO3vertical distribution, 1993 versus 1995 (2020)
    American Geophysical Union
    Details
    Publication Date: 2020-09-21
    Description: We compare differences and similarities in the annual stratospheric HNO3 cycle derived from ground‐based measurements at the South Pole during 1993 and 1995, after correcting an error in earlier published profile retrievals for 1993 which led to under estimation of mixing ratios. The data series presented here provide profiling over the range ∼16–48 km, and cover the fall‐winter‐spring cycle in the behavior of HNO3 in the extreme Antarctic with a large degree of temporal overlap. With the exception of one gap of 20 days, the combined data sets cover a full annual cycle. The record shows an increase in HNO3 above 30 km occurring about 20 days before sunset, which appears to be the result of higher altitude heterogeneous conversion of NOx as photolysis diminishes. Both years show a strong increase in HNO3 beginning about polar sunset, in a layer peaking at about 25 km, as additional NOx is heterogeneously converted to nitric acid. When temperatures drop to the polar stratospheric cloud (PSC) formation range near the end of May, gas phase HNO3 is rapidly reduced in the lower stratosphere, although at least 2–3 weeks of temperatures ≤192 K appear to be required to complete most of the gas‐phase removal at the upper end of the depletion range (22–25 km). Despite a significant difference in residual sulfate loading from the explosion of Mount Pinatubo, there appears to be little gross difference in the timing and effects of PSC formation in removing gas phase HNO3 in these 2 years, though removal may be more rapid in 1995. Incorporation of gas phase HNO3 into PSCs appears to be nearly complete up to ∼25 km by midwinter. We also see a repeat of the formation of gas phase HNO3 in the middle stratosphere in early midwinter of 1995 with about the same timing as in 1993, suggesting that this phenomenon is driven by a repetition of dynamical transport and appropriate temperatures and pressures in the polar night, and not (as has been suggested) by ion‐based heterogeneous chemistry that requires triggering by large relativistic electron fluxes. High‐altitude HNO3 production peaks during a period of ∼20 days, but appears to persist for up to ∼40 days in the 40–45 km range, ceasing well before sunrise. This HNO3 descends rapidly throughout the production period, at a rate in good agreement with theoretically determined midwinter subsidence rates. As noted in earlier studies, later warming of this region above PSC evaporation temperatures does not cause reappearance of large amounts of HNO3, indicating that most PSCs gravitationally sink out of the stratosphere before early spring. We present evidence that smaller PSCs do evaporate to ∼1 to 3.5 ppbv of HNO3 in the lower stratosphere, however, working downward from ∼25 km as temperatures rise during the late winter. There is a delay of ∼15 days after sunrise before photolysis causes significant depletion in the altitude range below ∼30 km, where subsidence has carried virtually all higher‐altitude HNO3 by polar sunrise. Some continued subsidence and photolysis combine to keep mixing ratios less than ∼5 ppbv below 30 km until the final breakdown of the vortex in November brings larger amounts of HNO3 with air from lower latitudes.
    Description: Published
    Description: 17739-17750
    Description: 5A. Ricerche polari e paleoclima
    Description: JCR Journal
    Keywords: ozone depletion ; HNO3 ; Antarctic stratosphere ; 01.01. Atmosphere
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
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    Applying the Values of Geoethics for Sustainable Speleotourism Development (2020)
    Springer Nature
    Details
    Publication Date: 2020-09-01
    Description: Establishing sustainable and responsible speleotourism development is a major challenge and involves complex activities. Adequate theoretical starting point is the application of geoethical values related to the conservation and protection of the caves to be used for touristic purposes. Positive and negative cases of human behaviors towards speleological geoheritage are discussed, in order to highlight what should be done in cave management to avoid malpractices and on what elements could be founded adequate strategies aimed at promoting sustainable speleotourism. This is important to tourism management organizations involved in the promotion of caves and in creating economic opportunities for local populations, while respecting cave ecosystems. Modern cave management must be focused on the protection of the cave ecosystems, finding ways to achieve at the same time an economic development of local communities. But this approach needs the adoption of a geoethical framework of values to be shared by all stakeholders involved so that successful cooperation can be achieved despite differences in interests and expectations. The aim of this paper is to raise the awareness about the need to apply the values of geoethics to speleotourism, stimulating new fields of discussion within the scientific and technical communities involved in studies and activities related to geotourism and geoheritage. The possibilities of developing new ways to manage caves, in order to promote a sustainable socio-economic development of local communities, have to be balanced with the protection of natural environments as much as possible. The proposed theoretical frameworks have the goal to increase the discussion on the best ways of connecting speleotourism to sustainable and responsible cave management, presenting two case studies, and pointing out potential solutions.
    Description: Open access funding provided by Istituto Nazionale di Geofisica e Vulcanologia within the CRUI-CARE Agreement
    Description: Published
    Description: id 73
    Description: 7SR AMBIENTE – Servizi e ricerca per la società
    Description: 1TM. Formazione
    Description: 2TM. Divulgazione Scientifica
    Description: JCR Journal
    Keywords: Geoethics ; Responsibility ; Sustainability ; Caves ; Speleotourism ; 05.03. Educational, History of Science, Public Issues ; 05.09. Miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 3
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    Stress tensor orientation derived from fault plane solutions in the southwestern Alps (2020)
    AGU
    Details
    Publication Date: 2020-10-27
    Description: Gephart and Forsyth's method has been applied to estimate stress orientations from earthquakefa ult planes olutionso f the southwesterAn lps, a regionw heret he tectonic stress regime is known to be fairly complex. Fault plane solutions have been either taken from the literature or computed using data from local and regional networks. Data refer to seismiecv entso f magnitudien the range2 .5-5.3w hicho ccurreidn the iastd ecades at depths between 0 and 25 km. Two zones with a different stress orientation have been identifiedi n the studieda rea (44.0ø-45.ø5 N, 6.5ø-8.5ø E)- the westernz one,c orresponding to the cresto f the alpine belt, where a high-dipm aximumc ompressivset ressi s found, and the easternz one (Alps chaint o Po Plain transition),c haracterizedb y an almosth orizontal E-W al and a nearly vertical as. Hypocenterso f earthquakesu sedf or stressi nversionl ie in the depthr anges0 -15 km and 5-25 km in the westerna nd easternz onesr, espectivelyT. he transitionb etweenth e two st•resdso mainsis very sharp,a nd this is alsoi ndicatedb y sp•ace distributiono f earthquakei ndividualm isfitst o the respectives tressm odels.T he findings of the present study are a good match for tectonic models which assume E-W compression derivedf rom the Adria-Europein teractiona nd producing:( 1) major thrustingp rocesses in the easterns ideo f the chaina nd (2) secondaryte nsionale ffectsa t very shallowd epth beneatht he alpineb elt crest( westernz oneo f the area studiedi n this work).
    Description: Published
    Description: 8171-8185
    Description: 4T. Sismicità dell'Italia
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 4
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    Evolution of the NOy-N2O correlation in the Antarctic stratosphere during 1993 and 1995 (2020)
    AGU
    Details
    Publication Date: 2020-10-16
    Description: The sources and sinks of stratospheric reactive nitrogen (NOy) in the Antarctic are known only qualitatively, because of the very few measurements of NOy available in this region. As a result, the effects of stratospheric NOy short- and long-term changes on the stratospheric concentration of ozone, water vapor, and other climate-forcing agents are still uncertain. To better understand the annual cycle of polar stratospheric NOy, we estimate its concentration in the Antarctic stratosphere during part of 1993 and throughout 1995. These estimates are obtained at seven potential temperature levels, extending from 18 to 30 km of altitude, and are associated with ground-based measurements of another tracer, N2O, in order to produce NOy-N2O correlation curves that can provide insights on nitrogen sources and sinks. To estimate NOy mixing ratios, we use ground-based and satellite measurements of major NOy constituents, connected by using air parcel trajectories and supplemented by model calculations of minor contributing species for which no suitable measurements exist. All the available NOy-N2O correlation points are averaged over three representative seasonal time periods in 1993 and six periods in 1995. Results show very similar correlation curves during the late summer and the fall of 1995, and again during the early spring 1993 compared with the early and late winter of 1995, although there are large seasonal changes due to transport and to condensation of NOy onto polar stratospheric clouds. We calculate a loss from the latter process of N = (6.3 ± 2.6) 107 kg of stratospheric nitrogen in the southern polar vortex during 1995.We also compare our correlation curves with those obtained in the Antarctic stratosphere during the Atmospheric Trace Molecule Spectroscopy mission ATMOS/ATLAS-3 in November 1994, finding important similarities but also critical differences that suggest that extravortex air is generally not an adequate representation of prewinter inner vortex conditions. Calculations of NOy winter removal in the Antarctic stratosphere which have used extra-vortex measurements as a surrogate for prewinter conditions may thus have underestimated true NOy removal. Our prewinter NOy estimates in the vortex core match values obtained by atmospheric models that incorporate upper atmospheric sources of NOy, supporting the belief that such sources have a significant effect on polar stratospheric NOy.
    Description: Published
    Description: 4428
    Description: 5A. Ricerche polari e paleoclima
    Description: JCR Journal
    Keywords: polar NOy ; NOy-N2O correlations ; denitrification ; 01.01. Atmosphere
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 5
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    Viscosity of high crystal content melts: dependence on solid fraction (2020)
    AGU
    Details
    Publication Date: 2020-12-18
    Description: The rheological properties of suspensions containing high solid fractions are investigated. Attention is focused on viscosity of silicate and magmatic melt systems. A general empirical equation which describes the relative viscosity of suspensions as a function of suspended solid fraction is proposed. In the limit of very dilute solid concentrations it reduces to the Einstein equation. The proposed relationship is satisfactorily applied to reproduce available experimental data relative to silicate melts. Moreover, the extrapolation of the model to very high concentrations is compared with experimental observations on partially‐melted granite.
    Description: Published
    Description: L22308
    Description: 3V. Proprietà chimico-fisiche dei magmi e dei prodotti vulcanici
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 6
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    Probabilistic Seismic Hazard Analysis at Regional and National Scales: State of the Art and Future Challenges (2020)
    American Geophysical Union
    Details
    Publication Date: 2020-09-01
    Description: Seismic hazard modeling is a multidisciplinary science that aims to forecast earthquake occurrence and its resultant ground shaking. Such models consist of a probabilistic framework that quantifies uncertainty across a complex system; typically, this includes at least two model components developed from Earth science: seismic source and ground motion models. Although there is no scientific prescription for the forecast length, the most common probabilistic seismic hazard analyses consider forecasting windows of 30 to 50 years, which are typically an engineering demand for building code purposes. These types of analyses are the topic of this review paper. Although the core methods and assumptions of seismic hazard modeling have largely remained unchanged for more than 50 years, we review the most recent initiatives, which face the difficult task of meeting both the increasingly sophisticated demands of society and keeping pace with advances in scientific understanding. A need for more accurate and spatially precise hazard forecasting must be balanced with increased quantification of uncertainty and new challenges such as moving from time‐independent hazard to forecasts that are time dependent and specific to the time period of interest. Meeting these challenges requires the development of science‐driven models, which integrate all information available, the adoption of proper mathematical frameworks to quantify the different types of uncertainties in the hazard model, and the development of a proper testing phase of the model to quantify its consistency and skill. We review the state of the art of the National Seismic Hazard Modeling and how the most innovative approaches try to address future challenges.
    Description: Published
    Description: e2019RG000653
    Description: 6T. Studi di pericolosità sismica e da maremoto
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 7
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    On the correlation between solar activity and large earthquakes worldwide (2021)
    Springer Nature
    Details
    Publication Date: 2021-03-03
    Description: Large earthquakes occurring worldwide have long been recognized to be non Poisson distributed, so involving some large scale correlation mechanism, which could be internal or external to the Earth. Till now, no statistically significant correlation of the global seismicity with one of the possible mechanisms has been demonstrated yet. In this paper, we analyze 20 years of proton density and velocity data, as recorded by the SOHO satellite, and the worldwide seismicity in the corresponding period, as reported by the ISC-GEM catalogue. We found clear correlation between proton density and the occurrence of large earthquakes (M 〉 5.6), with a time shift of one day. The significance of such correlation is very high, with probability to be wrong lower than 10-5. The correlation increases with the magnitude threshold of the seismic catalogue. A tentative model explaining such a correlation is also proposed, in terms of the reverse piezoelectric effect induced by the applied electric field related to the proton density. This result opens new perspectives in seismological interpretations, as well as in earthquake forecast.
    Description: Published
    Description: 11495
    Description: 7T. Variazioni delle caratteristiche crostali e precursori sismici
    Description: JCR Journal
    Keywords: correlation ; solar activity ; large earthquakes worldwide
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 8
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    Gas isotopic signatures (He, C, and Ar) in the Lake Kivu region (western branch of the East African rift system): Geodynamic and volcanological implications (2021)
    AGU
    Details
    Publication Date: 2021-03-02
    Description: On 17 January 2002, the city of Goma was partly destroyed by two of the several lava flows erupted from a roughly N-S oriented fracture system opened along the southern flank of Mount Nyiragongo (Democratic Republic of Congo), in the western branch of the East African rift system. A humanitarian and scientific response was promptly organized by international, governmental, and nongovernmental agencies coordinated by the United Nations and the European Union. Among the different scientific projects undertaken to study the mechanisms triggering this and possible future eruptions, we focused on the isotopic (He, C, and Ar) analysis of the magmatic-hydrothermal and cold gas discharges related to the Nyiragongo volcanic system, the Kivu and Virunga region. The studied area includes the Nyiragongo volcano, its surroundings, and peripheral areas inside and outside the rift. They have been subdivided into seven regions characterized by distinct 3He/4He (expressed as R/Rair) ratios and/or d13C-CO2 values. The Nyiragongo summit crater fumaroles, whose R/Rair and d13C-CO2 values are up to 8.73 and from 3.5% to 4.0% VPDB, respectively, show a clear mantle, mid-ocean ridge basalt (MORB)-like contribution. Similar mantle-like He isotopic values (6.5–8.3 R/Rair) are also found in CO2-rich gas emanations (mazukus) along the northern shoreline of Lake Kivu main basin, whereas the 13dC-CO2 values range from 5.3% to 6.8% VPDB. The mantle influence progressively decreases in (1) dissolved gases of Lake Kivu (2.6–5.5 R/Rair) and (2) the distal gas discharges within and outside the two sides of the rift (from 0.1 to 1.7 R/Rair). Similarly, d13C-CO2 ratios of the peripheral gas emissions are lighter (from 5.9% to 11.6% VPDB) than those of the crater fumaroles. Therefore, the spatial distribution of He and C signatures in the Lake Kivu region is mainly produced by mixing of mantle-related (e.g., Nyiragongo crater fumaroles and/or mazukus gases) and crustal-related (e.g., gas discharges in the Archean craton) fluids. The CO2/3He ratio (up to 10 1010) is 1 order of magnitude higher than those found in MORB, and it is due to the increasing solubility of CO2 in the foiditic magma feeding the Nyiragongo volcano. However, the exceptionally high 40Ar*/4He ratio (up to 8.7) of the Nyiragongo crater fumaroles may be related to the difference between He and Ar solubility in the magmatic source. The results of the present investigation suggest that in this area the uprising of mantle-originated f luids seems strongly controlled by regional tectonics in relation to the geodynamic assessment of the rift. These fluids are mainly localized in a relatively small zone between Lake Kivu and Nyiragongo volcano, with important implications in terms of volcanic activity.
    Description: Published
    Description: B01205
    Description: 6V. Pericolosità vulcanica e contributi alla stima del rischio
    Description: 6A. Geochimica per l'ambiente e geologia medica
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 9
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    Water and gas chemistry at Lake Kivu (DRC): Geochemical evidence of vertical and horizontal heterogeneities in a multibasin structure (2021)
    AGU
    Details
    Publication Date: 2021-03-02
    Description: Waters and dissolved gases collected along vertical profiles in the five basins (Main, Kabuno Bay, Kalehe, Ishungu, and Bukavu) forming the 485 m deep Lake Kivu (Democratic Republic of the Congo) were analyzed to provide a geochemical conceptual model of the several processes controlling lake chemistry. The measured horizontal and vertical variations of water and gas compositions suggest that each basin has distinct chemical features produced by (1) different contribution from long circulating fluid system containing magmatic CO2, responsible of the huge CO2(CH4)-rich reservoir hosted within the deep lake water; (2) spatial variations of the biomass distribution and/or speciation; and (3) solutes from water-rock interactions. The Kabuno Bay basin is characterized by the highest rate of magmatic fluid input. Accordingly, this basin must be considered the most hazardous site for possible gas outburst that could be triggered by the activity of the Nyiragongo and Nyamulagira volcanoes, located a few kilometers north of the lake.
    Description: Published
    Description: Q02005
    Description: 6V. Pericolosità vulcanica e contributi alla stima del rischio
    Description: 6A. Geochimica per l'ambiente e geologia medica
    Description: JCR Journal
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  • 10
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    Assessment of earthquake locations in 3D deterministic velocity models: a case study from the Altotiberina Near Fault Observatory (Italy) (2020)
    American Geophysical Union
    Details
    Publication Date: 2021-07-14
    Description: An edited version of this paper was published by AGU. Copyright (2016) American Geophysical Union.
    Description: The accuracy of earthquake locations and their correspondence with subsurface geology depends strongly on the accuracy of the available seismic velocity model. Most modern methods to construct a velocity model for earthquake location are based on the inversion of passive source seismological data. Another approach is the integration of high-resolution geological and geophysical data to construct deterministic velocity models in which earthquake locations can be directly correlated to the geological structures. Such models have to be kinematically consistent with independent seismological data in order to provide precise hypocenter solutions. We present the Altotiberina (AT) seismic model, a three-dimensional velocity model for the Upper Tiber Valley region (Northern Apennines, Italy), constructed by combining 300 km of seismic reflection profiles, 6 deep boreholes (down to 5 km depth), detailed data from geological surveys and direct measurements of P- and S-wave velocities performed in situ and in laboratory. We assess the robustness of the AT seismic model by locating 11,713 earthquakes with a non-linear, global-search inversion method and comparing the probabilistic hypocenter solutions to those calculated in three previously published velocity models, constructed by inverting passive seismological data only. Our results demonstrate that the AT seismic model is able to provide higher-quality hypocenter locations than the previous velocity models. Earthquake locations are consistent with the subsurface geological structures and show a high degree of spatial correlation with specific lithostratigraphic units, suggesting a lithological control on the seismic activity evolution.
    Description: Published
    Description: 8113-8135
    Description: 4T. Sismicità dell'Italia
    Description: JCR Journal
    Keywords: deterministic velocity model ; earthquakes ; nonlinear hypocenter location ; lithological control on seismicity ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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