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  • 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring  (89)
  • Arctic  (24)
  • 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
  • 04.02. Exploration geophysics
  • JSTOR Archive Collection Business II
  • American Geophysical Union  (117)
  • Wiley  (9)
  • American Chemical Society (ACS)
  • EGU
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  • 1
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    The Erasmus+ BridgET project: A European partnership to renew teaching in marine geosciences (2024)
    EGU
    Details
    Publication Date: 2024-01-29
    Description: Recent advances in underwater and airborne robotic systems and ocean technologies have opened new perspectives in marine geology and its applications in the context of coastal and marine economic activities, whose sustainable development is increasingly acknowledged as a pillar for the new blue economy. BridgET (Bridging the gap between the land and the sea in a virtual Environment for innovative Teaching and community involvement in the science of climate change-induced marine and coastal geohazard) is an EU ERASMUS+ project designed to develop innovative and inclusive teaching methods to address a growing demand for strategic skills and scientific expertise in the field of 3D geological mapping of coastal environments. Seamless integration of the wide variety of multisource and multiscale onshore, nearshore and offshore geospatial data is indeed one of the main areas for improvement in the implementation of efficient management practices in coastal regions, where climate change, rising sea level, and geohazards are considerable environmental issues. BridgET involves a partnership consisting of six European universities with outstanding expertise in the study of geological hazards, and climate impacts in marine and coastal areas (i.e., University of Milano-Bicocca, Italy, Arctic University of Tromsø/CAGE - Norway, National and Kapodistrian University of Athens - Greece, Kiel University, Germany, University of Liege – Belgium, and the University of Malta), two Italian research institutes (INGV and INAF) and a German company (Orthodrone GmvH) specialized in UAS-based LiDAR and photogrammetry data acquisition services and analyses. Project implementation relies on delivering learning and teaching activities through dedicated summer schools for MSc students by efficiently combining the partner’s expertise. Schools focus on giving students a hands-on experience with the variety of methods and procedures adopted in geospatial data acquisition and processing, including the use of drones (Uncrewed Aerial System – UAS), acoustic remote sensing techniques and underwater robotic systems, together with the progress made by computer visions and digital image analysis by using Artificial Intelligence (AI). Students are also introduced to the opportunity to easily examine multiple viewing angles of the seabed and coastal 3D surfaces by using immersive and nonimmersive Virtual Reality (VR), to bring them closer to a more straightforward observation of geomorphological data and geological phenomena. The first Summer School was held in Santorini between the 3rd and 14th of October, 2022. It was attended by 26 students coming from 13 different countries. Teaching and learning activities included several classrooms, fieldwork, laboratory sessions, and seven seminars and cultural visits dealing with transversal topics, allowing students to approach an integrated understanding of human interaction with physical processes from social and economic perspectives. In this presentation, we give examples of course content used to allow students to develop a deeper understanding of theoretical and practical knowledge of climate-induced coastal and marine geohazards. Participants' opinions on the quality of the offered learning/training activities of the Erasmus+ BridgET Santorini Summer School (collected through a dedicated questionnaire) will also be presented. Erasmus+ BridgET Team: Varvara Antoniou, Fabio Luca Bonali, Clara Drummer, Theynushya Esalingam, Luca Fallati, Susanna Falsaperla, Felix Gross, Hans-Balder havenith, Juri Klusak, Sebastian Krastel, Iver Martens, Aaron Micallef, Paraskevi Nomikou, Giuliana Panieri, Danilo Reitano, Julian Teege, Alessandro Tibaldi, Andrea Giulia Varzi, Fabio Vitello, Othonas Vlasopoulos
    Description: Published
    Description: Vienna (Austria)
    Description: OSA4: Ambiente marino, fascia costiera ed Oceanografia operativa
    Keywords: marine geosciences ; education ; Europe ; 04.02. Exploration geophysics ; 05.03. Educational, History of Science, Public Issues ; 05.04. Instrumentation and techniques of general interest
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Conference paper
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  • 2
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    Decadal observations of internal wave energy, shear, and mixing in the western Arctic Ocean (2022)
    American Geophysical Union
    Details
    Publication Date: 2022-10-26
    Description: Author Posting. © American Geophysical Union, 2022. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 127(5), (2022): e2021JC018056, https://doi.org/10.1029/2021jc018056.
    Description: As Arctic sea ice declines, wind energy has increasing access to the upper ocean, with potential consequences for ocean mixing, stratification, and turbulent heat fluxes. Here, we investigate the relationships between internal wave energy, turbulent dissipation, and ice concentration and draft using mooring data collected in the Beaufort Sea during 2003–2018. We focus on the 50–300 m depth range, using velocity and CTD records to estimate near-inertial shear and energy, a finescale parameterization to infer turbulent dissipation rates, and ice draft observations to characterize the ice cover. All quantities varied widely on monthly and interannual timescales. Seasonally, near-inertial energy increased when ice concentration and ice draft were low, but shear and dissipation did not. We show that this apparent contradiction occurred due to the vertical scales of internal wave energy, with open water associated with larger vertical scales. These larger vertical scale motions are associated with less shear, and tend to result in less dissipation. This relationship led to a seasonality in the correlation between shear and energy. This correlation was largest in the spring beneath full ice cover and smallest in the summer and fall when the ice had deteriorated. When considering interannually averaged properties, the year-to-year variability and the short ice-free season currently obscure any potential trend. Implications for the future seasonal and interannual evolution of the Arctic Ocean and sea ice cover are discussed.
    Description: This work was supported by the Postdoctoral Scholar Program at Woods Hole Oceanographic Institution, with funding provided by the Weston Howland Jr. Postdoctoral Scholarship. S. T. Cole was supported by Office of Naval Research grant N00014-16-1-2381.
    Description: 2022-10-14
    Keywords: Arctic ; Internal waves ; Mixing ; Sea ice ; Turbulence
    Repository Name: Woods Hole Open Access Server
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  • 3
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    Fate of warm Pacific water in the Arctic Basin (2022)
    American Geophysical Union
    Details
    Publication Date: 2022-05-27
    Description: Author Posting. © American Geophysical Union, 2021. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 48(20), (2021): e2021GL094693, https://doi.org/10.1029/2021GL094693.
    Description: Pacific Summer Water (PSW) plays a critical role in the ecosystem of the western Arctic Ocean, impacting sea-ice melt and providing freshwater to the basin. Most of the water exits the Chukchi Sea shelf through Barrow Canyon, but the manner in which this occurs and the ultimate fate of the water remain uncertain. Using an extensive collection of historical hydrographic and velocity data, we demonstrate how the PSW outflow depends on different wind conditions, dictating whether the warm water progresses eastward or westward away from the canyon. The current carrying the water westward along the continental slope splits into different branches, influenced by the strength and extent of the Beaufort Gyre, while the eastward penetration of PSW along the shelfbreak is limited. Our results provide the first broad-scale view of how PSW is transferred from the shelf to the basin, highlighting the role of winds, boundary currents, and eddy exchange.
    Description: Funding for the project was provided by National Science Foundation grant OPP-1733564 and National Oceanic and Atmospheric Administration grant NA14OAR4320158 (P. Lin, R. S. Pickart, J. Li), and Trond Mohn Foundation Grant BFS2016REK01 (K. Vage).
    Description: 2022-04-01
    Keywords: Pacific Summer Water ; Arctic ; Beaufort Gyre ; Chukchi Slope Current ; Beaufort Shelfbreak Jet ; Barrow Canyon
    Repository Name: Woods Hole Open Access Server
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  • 4
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    Integrated use of unmanned aerial vehicle photogrammetry and terrestrial laser scanning to support archaeological analysis: The Acropolis of Selinunte case (Sicily, Italy) (2021)
    Wiley
    Details
    Publication Date: 2021-06-14
    Description: Southwestern Sicily is an area of infrequent seismic activity; however, some studies carried out in the archaeological Selinunte site suggest that, between the fourth century BC and the early Middle Ages, probably at least two earthquakes strucked this area with enough energy to damage and cause the collapse and kinematics of much of the architecture of Selinunte. Take into account that, in 2008, a noninvasive archaeological prospection and traditional data gathering methods along the Acropolis north fortifications were carried out. Following these first studies, after about 10 years, a new geophysical campaign was carried out. This second campaign benefited from the application of modern technologies for the acquisition and processing of the point cloud data on the northern part of the Acropolis, like terrestrial laser scanning and unmanned aerial vehicle photogrammetry. In this paper, we present the application of these techniques and a strategy for their integration for the 3D modelling of buildings and cultural heritages. We show how the integration of data acquired independently by these two techniques is an added value able to overcome the intrinsic limits of the individual techniques. The application to Selinunte's Acropolis allowed it to highlight and measure with high accuracy fractures, dislocation, inclinations of walls, depressions of some areas and other interesting observations, which may be important starting points for future investigations.
    Description: Published
    Description: 153-165
    Description: 2IT. Laboratori analitici e sperimentali
    Description: JCR Journal
    Keywords: 3D reconstruction ; archaeological survey ; digital elevation model ; Selinunte Archaeological Park ; terrestrial laser scanning ; unmanned aerial vehicle photogrammetry ; 05.04. Instrumentation and techniques of general interest ; 04.02. Exploration geophysics ; 05.02. Data dissemination ; 05.06. Methods
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 5
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    Limited presence of permafrost dissolved organic matter in the Kolyma River, Siberia revealed by ramped oxidation (2021)
    American Geophysical Union
    Details
    Publication Date: 2022-10-26
    Description: Author Posting. © American Geophysical Union, 2021. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Biogeosciences 126(7), (2021): e2020JG005977, https://doi.org/10.1029/2020JG005977.
    Description: Increasing Arctic temperatures are thawing permafrost soils and liberating ancient organic matter, but the fate of this material remains unclear. Thawing of permafrost releases dissolved organic matter (DOM) into fluvial networks. Unfortunately, tracking this material in Arctic rivers such as the Kolyma River in Siberia has proven challenging due to its high biodegradability. Here, we evaluate late summer abruptly thawed yedoma permafrost dissolved organic carbon (DOC) inputs from Duvannyi Yar. We implemented ultrahigh-resolution mass spectrometry alongside ramped pyrolysis oxidation (RPO) and isotopic analyses. These approaches offer insight into DOM chemical composition and DOC radiocarbon values of thermochemical components for a permafrost thaw stream, the Kolyma River, and their biodegraded counterparts (n = 4). The highly aliphatic molecular formula found in undegraded permafrost DOM contrasted with the comparatively aliphatic-poor formula of Kolyma River DOM, represented by an 8.9% and 2.6% relative abundance, respectively, suggesting minimal inputs of undegraded permafrost DOM in the river. RPO radiocarbon fractions of Kolyma River DOC exhibited no “hidden” aged component indicative of permafrost influence. Thermostability analyses suggested that there was limited biodegraded permafrost DOC in the Kolyma River, in part determined by the formation of high-activation energy (thermally stable) biodegradation components in permafrost DOM that were lacking in the Kolyma River. A mixing model based on thermostability and radiocarbon allowed us to estimate a maximum input of between 0.8% and 7.7% of this Pleistocene-aged permafrost to the Kolyma River DOC. Ultimately, our findings highlight that export of modern terrestrial DOC currently overwhelms any permafrost DOC inputs in the Kolyma River.
    Description: This work was funded by NSF grants ANT-1203885 and PLR-1500169 to R.G.M.S. The work was also supported by the National Science Foundation Division of Chemistry through DMR-1644779 and the State of Florida.
    Description: 2022-01-09
    Keywords: Permafrost ; Dissolved organic carbon ; Dissolved organic matter ; FT-ICR MS ; Ramped pyrolysis oxidation ; Arctic
    Repository Name: Woods Hole Open Access Server
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  • 6
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    Active Extension in a Foreland Trapped Between Two Contractional Chains: The South Apulia Fault System (SAFS) (2020)
    Wiley
    Details
    Publication Date: 2020-07-08
    Description: The response of continental forelands to subduction and collision is a widely investigated topic in geodynamics. The deformation occurring within a foreland shared by two opposite‐verging chains, however, is uncommon and poorly understood. The Apulia Swell in the southern end of the Adria microplate (Africa‐Europe plate boundary, central Mediterranean Sea) represents one of these cases, as it is the common foreland of the SW verging Albanides‐Hellenides and the NE verging Southern Apennines merging into the SSE verging Calabrian Arc. We investigated the internal deformation of the Apulia Swell using multiscale geophysical data: multichannel seismic profiles recording up to 12‐s two‐way time (TWT) for a consistent image of the upper crust; high‐resolution multichannel seismic profiles, high‐resolution multibeam bathymetry, and CHIRP profiles acquired by R/V OGS Explora to constrain the Quaternary geological record. The results of our analyses characterize the geometry of the South Apulia Fault System (SAFS), a 100‐km‐long and 12‐km‐wide structure attesting an extensional (and possibly transtensional) response of the foreland to the two contractional fronts. The SAFS consists of two NW‐SE right‐stepping master faults and several secondary structures. The SAFS activity spans from the Early Pleistocene through the Holocene, as testified by the bathymetric and high‐resolution seismic data, with long‐term slip rates in the range of 0.2–0.4 mm/yr. Considering the position within an area with few or none other active faults in the surroundings, the dimension, and the activity rates, the SAFS can be a candidate causative fault of the 20 February 1743, M 6.7, earthquake.
    Description: Italian Ministry for Education, University, and Research (MIUR), Premiale 2014 D. M. 291 03/05/2016.
    Description: Published
    Description: e2020TC006116
    Description: 2T. Deformazione crostale attiva
    Description: 2TR. Ricostruzione e modellazione della struttura crostale
    Description: JCR Journal
    Keywords: active tectonics ; apulia ; south apulia fault system ; 1743 earthquake ; marine geology ; stable continental region ; ionian sea ; active faults ; subsurface geology ; seismic interpretation ; 04.04. Geology ; 04.07. Tectonophysics ; 04.02. Exploration geophysics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 7
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    Arctic amplification of global warming strengthened by sunlight oxidation of permafrost carbon to CO2 (2020)
    Wiley
    Details
    Publication Date: 2022-10-26
    Description: © The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Bowen, J. C., Ward, C. P., Kling, G. W., & Cory, R. M. Arctic amplification of global warming strengthened by sunlight oxidation of permafrost carbon to CO2. Geophysical Research Letters, 47(12), (2020): e2020GL087085, doi:10.1029/2020GL087085.
    Description: Once thawed, up to 15% of the ∼1,000 Pg of organic carbon (C) in arctic permafrost soils may be oxidized to carbon dioxide (CO2) by 2,100, amplifying climate change. However, predictions of this amplification strength ignore the oxidation of permafrost C to CO2 in surface waters (photomineralization). We characterized the wavelength dependence of permafrost dissolved organic carbon (DOC) photomineralization and demonstrate that iron catalyzes photomineralization of old DOC (4,000–6,300 a BP) derived from soil lignin and tannin. Rates of CO2 production from photomineralization of permafrost DOC are twofold higher than for modern DOC. Given that model predictions of future net loss of ecosystem C from thawing permafrost do not include the loss of CO2 to the atmosphere from DOC photomineralization, current predictions of an average of 208 Pg C loss by 2,299 may be too low by ~14%.
    Description: This research was supported by National Science Foundation (NSF) CAREER 1351745 (R.M.C.), DEB 1637459 and 1754835 (G.W.K.), the Camille and Henry Dreyfus Postdoctoral Program in Environmental Chemistry (R.M.C. and C.P.W.), the Frank and Lisina Hock Endowed Fund (C.P.W.), and the NOSAMS Graduate Student Internship Program (J.C.B.).
    Keywords: Photochemistry ; Permafrost ; Arctic ; Carbon cycling ; Dissolved organic carbon
    Repository Name: Woods Hole Open Access Server
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  • 8
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    Plant uptake offsets silica release from a large arctic tundra wildfire (2020)
    American Geophysical Union
    Details
    Publication Date: 2022-05-26
    Description: © The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Carey, J. C., Abbott, B. W., & Rocha, A. V. Plant uptake offsets silica release from a large arctic tundra wildfire. Earth’s Future, 7(9), (2019): 1044-1057, doi:10.1029/2019EF001149.
    Description: Rapid climate change at high latitudes is projected to increase wildfire extent in tundra ecosystems by up to fivefold by the end of the century. Tundra wildfire could alter terrestrial silica (SiO2) cycling by restructuring surface vegetation and by deepening the seasonally thawed active layer. These changes could influence the availability of silica in terrestrial permafrost ecosystems and alter lateral exports to downstream marine waters, where silica is often a limiting nutrient. In this context, we investigated the effects of the largest Arctic tundra fire in recent times on plant and peat amorphous silica content and dissolved silica concentration in streams. Ten years after the fire, vegetation in burned areas had 73% more silica in aboveground biomass compared to adjacent, unburned areas. This increase in plant silica was attributable to significantly higher plant silica concentration in bryophytes and increased prevalence of silica‐rich gramminoids in burned areas. Tundra fire redistributed peat silica, with burned areas containing significantly higher amorphous silica concentrations in the O‐layer, but 29% less silica in peat overall due to shallower peat depth post burn. Despite these dramatic differences in terrestrial silica dynamics, dissolved silica concentration in tributaries draining burned catchments did not differ from unburned catchments, potentially due to the increased uptake by terrestrial vegetation. Together, these results suggest that tundra wildfire enhances terrestrial availability of silica via permafrost degradation and associated weathering, but that changes in lateral silica export may depend on vegetation uptake during the first decade of postwildfire succession.
    Description: This research was supported by NSF EAR PD Fellowship 1451527 to J. C. Carey, NSF grants 1065587 and 1026843 to the Marine Biological Laboratory, and NSF grant 1556772 to the University of Notre Dame. B. W. Abbott was supported by the Plant and Wildlife Department and College of Life Sciences at Brigham Young University. Data are available from the Dryad Digital Repository (doi:10.5061/dryad.79q74n7). We thank Ian Klupar for field assistance. R. Fulweber at the Toolik Field Station GIS & Remote Sensing Office performed watershed delineations and other spatial analysis. We thank the NSF Arctic LTER and the UAF Toolik Field Station for logistical support. We declare no conflicts of interest.
    Keywords: silica ; Arctic ; tundra ; wildfire ; vegetation ; permafrost
    Repository Name: Woods Hole Open Access Server
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  • 9
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    Overview of the Arctic Sea state and boundary layer physics program (2019)
    American Geophysical Union
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © American Geophysical Union, 2018. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research-Oceans 123(12), (2018): 8674-8687, doi:10.1002/2018JC013766.
    Description: A large collaborative program has studied the coupled air‐ice‐ocean‐wave processes occurring in the Arctic during the autumn ice advance. The program included a field campaign in the western Arctic during the autumn of 2015, with in situ data collection and both aerial and satellite remote sensing. Many of the analyses have focused on using and improving forecast models. Summarizing and synthesizing the results from a series of separate papers, the overall view is of an Arctic shifting to a more seasonal system. The dramatic increase in open water extent and duration in the autumn means that large surface waves and significant surface heat fluxes are now common. When refreezing finally does occur, it is a highly variable process in space and time. Wind and wave events drive episodic advances and retreats of the ice edge, with associated variations in sea ice formation types (e.g., pancakes, nilas). This variability becomes imprinted on the winter ice cover, which in turn affects the melt season the following year.
    Description: This program was supported by the Office of Naval Research, Code 32, under Program Managers Scott Harper and Martin Jeffries. The crew of R/V Sikuliaq provide outstanding support in collecting the field data, and the US National Ice Center, German Aerospace Center (DLR), and European Space Agency facilitated the remote sensing collections and daily analysis products. RADARSAT‐2 Data and Products are from MacDonald, Dettwiler, and Associates Ltd., courtesy of the U.S. National Ice Center. Data, supporting information, and a cruise report can be found at http://www.apl.uw.edu/arcticseastate
    Keywords: Arctic ; waves ; autumn ; sea ice ; Beaufort ; flux
    Repository Name: Woods Hole Open Access Server
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  • 10
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    Stable Isotope clues to the formation and evolution of refrozen melt ponds on Arctic Sea ice. (2019)
    American Geophysical Union
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © American Geophysical Union, 2018. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research-Oceans 123(12), (2018): 8887-8901, doi:10.1029/2018JC013797.
    Description: Sea ice is one of the determining parameters of the climate system. The presence of melt ponds on the surface of Arctic sea ice plays a critical role in the mass balance of sea ice. A total of nine cores was collected from multiyear ice refrozen melt ponds and adjacent hummocks during the 2015 Arctic Sea State research cruise. The depth profiles of water isotopes, salinity, and ice texture for these sea ice cores were examined to provide information about the development of refrozen melt ponds and water balance generation processes, which are otherwise difficult to acquire. The presence of meteoric water with low oxygen isotope values as relatively thin layers indicates melt pond water stability and little mixing during formation and refreezing. The hydrochemical characteristics of refrozen melt pond and seawater depth profiles indicate little snowmelt enters the upper ocean during melt pond refreezing. Due to the seasonal characters of deuterium excess for Arctic precipitation, water balance calculations utilizing two isotopic tracers (oxygen isotope and deuterium excess) suggest that besides the melt of snow cover, the precipitation input in the melt season may also play a role in the evolution of melt ponds. The dual‐isotope mixing model developed here may become more valuable in a future scenario of increasing Arctic precipitation. The layers of meteoric origin were found at different depths in the refrozen melt pond ice cores. Surface topography information collected at several core sites was examined for possible explanations of different structures of refrozen melt ponds.
    Description: The coauthors (S. F. A., S. S., T. M., and B. W.) wish to thank the other DRI participants and the Captain and crew of the Sikuliaq's October 2015 cruise for their assistance in the sample collections analyzed in the paper. Jim Thomson (Chief Scientist), Scott Harper (ONR Program Manager), and Martin Jeffries (ONR Program Manager) are particularly acknowledged for their unwavering assistance and leadership during the 5 years of the SeaState DRI. We thank Guy Williams for production of the aerial photo mosaic. Funding from the Office of Naval Research N00014‐13‐1‐0435 (S. F. A. and B. W.), N00014‐13‐1‐0434 (S. S.), and N00014‐13‐1‐0446 (T. M.) supported this research through grants to UTSA, UColorado, and WHOI, respectively. This project was also funded (in part) by the University of Texas at San Antonio, Office of the Vice President for Research (Y. G. and S. F. A.). Data for the stable isotope mixing models used in this study are shown in supporting information Tables S1–S3.
    Description: 2019-05-15
    Keywords: Arctic ; sea ice ; isotope tracer ; melt pond ; oxygen isotope ; deuterium excess
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  • 11
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    Ice nucleating particles carried from below a phytoplankton bloom to the arctic atmosphere (2019)
    American Geophysical Union
    Details
    Publication Date: 2022-10-26
    Description: Author Posting. © American Geophysical Union, 2019. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 46(14), (2019): 8572-8581, doi: 10.1029/2019GL083039.
    Description: As Arctic temperatures rise at twice the global rate, sea ice is diminishing more quickly than models can predict. Processes that dictate Arctic cloud formation and impacts on the atmospheric energy budget are poorly understood, yet crucial for evaluating the rapidly changing Arctic. In parallel, warmer temperatures afford conditions favorable for productivity of microorganisms that can effectively serve as ice nucleating particles (INPs). Yet the sources of marine biologically derived INPs remain largely unknown due to limited observations. Here we show, for the first time, how biologically derived INPs were likely transported hundreds of kilometers from deep Bering Strait waters and upwelled to the Arctic Ocean surface to become airborne, a process dependent upon a summertime phytoplankton bloom, bacterial respiration, ocean dynamics, and wind‐driven mixing. Given projected enhancement in marine productivity, combined oceanic and atmospheric transport mechanisms may play a crucial role in provision of INPs from blooms to the Arctic atmosphere.
    Description: We sincerely thank the U.S. Coast Guard and crew of the Healy for assistance with equipment installation and guidance, operation of the underway and CTD systems, and general operation of the vessel during transit and at targeted sampling stations. We would also like to thank Allan Bertram, Meng Si, Victoria Irish, and Benjamin Murray for providing INP data from their previous studies. J. M. C., R. P., P. L., L. T., and E. B. were funded by the National Oceanic and Atmospheric Administration (NOAA)’s Arctic Research Program. J. C. was supported by the NOAA Experiential Research & Training Opportunities (NERTO) program. T. A. and N. C. were supported through the NOAA Earnest F. Hollings Scholarship program. A. P. was funded by the National Science Foundation under Grant PLR‐1303617. Russel C. Schnell and Michael Spall are acknowledged for insightful discussions during data analysis and interpretation. There are no financial conflicts of interest for any author. INP data are available in the supporting information, while remaining DBO‐NCIS data presented in the manuscript are available online (at https://www2.whoi.edu/site/dboncis/).
    Description: 2020-01-15
    Keywords: Arctic ; Ice nucleation ; Phytoplankton bloom ; Aerosol‐cloud interactions ; Arctic aerosol
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  • 12
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    Submarine permafrost map in the arctic modeled using 1-D transient heat flux (SuPerMAP) (2019)
    American Geophysical Union
    Details
    Publication Date: 2022-10-27
    Description: Author Posting. © American Geophysical Union, 2019. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research-Oceans 124(6), (2019): 3490-3507, doi:10.1029/2018JC014675.
    Description: Offshore permafrost plays a role in the global climate system, but observations of permafrost thickness, state, and composition are limited to specific regions. The current global permafrost map shows potential offshore permafrost distribution based on bathymetry and global sea level rise. As a first‐order estimate, we employ a heat transfer model to calculate the subsurface temperature field. Our model uses dynamic upper boundary conditions that synthesize Earth System Model air temperature, ice mass distribution and thickness, and global sea level reconstruction and applies globally distributed geothermal heat flux as a lower boundary condition. Sea level reconstruction accounts for differences between marine and terrestrial sedimentation history. Sediment composition and pore water salinity are integrated in the model. Model runs for 450 ka for cross‐shelf transects were used to initialize the model for circumarctic modeling for the past 50 ka. Preindustrial submarine permafrost (i.e., cryotic sediment), modeled at 12.5‐km spatial resolution, lies beneath almost 2.5 ×106km2 of the Arctic shelf. Our simple modeling approach results in estimates of distribution of cryotic sediment that are similar to the current global map and recent seismically delineated permafrost distributions for the Beaufort and Kara seas, suggesting that sea level is a first‐order determinant for submarine permafrost distribution. Ice content and sediment thermal conductivity are also important for determining rates of permafrost thickness change. The model provides a consistent circumarctic approach to map submarine permafrost and to estimate the dynamics of permafrost in the past.
    Description: Boundary condition data are available online via the sources referenced in the manuscript. This work was partially funded by a Helmholtz Association of Research Centres (HGF) Joint Russian‐German Research Group (HGF JRG 100). This study is part of a project that has received funding from the European Unions Horizon 2020 research and innovation program under grant agreement 773421. Submarine permafrost studies in the Kara and Laptev Seas were supported by Russian Foundation for Basic Research (RFBR/RFFI) grants 18‐05‐60004 and 18‐05‐70091, respectively. The International Permafrost Association (IPA) and the Association for Polar Early Career Scientists (APECS) supported research coordination that led to this study. We acknowledge coordination support of the World Climate Research Programme (WCRP) through their core project on Climate and Cryosphere (CliC). Thanks to Martin Jakobsson for providing a digitized version of the preliminary IHO delineation of the Arctic seas and to Guy Masters for access to the observational geothermal database. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
    Description: 2019-10-17
    Keywords: Submarine permafrost ; Arctic ; Cryosphere ; Sea level
    Repository Name: Woods Hole Open Access Server
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  • 13
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    Insights into shallow magmatic processes at Kīlauea Volcano, Hawaiʻi, from a multiyear continuous gravity time series (2017)
    American Geophysical Union
    Details
    Publication Date: 2021-02-10
    Description: Continuous gravity data collected near the summit eruptive vent at Kīlauea Volcano, Hawaiʻi, during 2011–2015 show a strong correlation with summit-area surface deformation and the level of the lava lake within the vent over periods of days to weeks, suggesting that changes in gravity reflect variations in volcanic activity. Joint analysis of gravity and lava level time series data indicates that over the entire time period studied, the average density of the lava within the upper tens to hundreds of meters of the summit eruptive vent remained low—approximately 1000–1500 kg/m^3. The ratio of gravity change (adjusted for Earth tides and instrumental drift) to lava level change measured over 15 day windows rose gradually over the course of 2011–2015, probably reflecting either (1) a small increase in the density of lava within the eruptive vent or (2) an increase in the volume of lava within the vent due to gradual vent enlargement. Superimposed on the overall time series were transient spikes of mass change associated with inflation and deflation of Kīlauea’s summit and coincident changes in lava level. The unexpectedly strong mass variations during these episodes suggest magma flux to and from the shallow magmatic system without commensurate deformation, perhaps indicating magma accumulation within, and withdrawal from, void space—a process that might not otherwise be apparent from lava level and deformation data alone. Continuous gravity data thus provide unique insights into magmatic processes, arguing for continued application of the method at other frequently active volcanoes.
    Description: Published
    Description: 5477–5492
    Description: 2V. Dinamiche di unrest e scenari pre-eruttivi
    Description: JCR Journal
    Description: restricted
    Keywords: Kīlauea Volcano; gravity changes; lava lake; volcano monitoring ; 04. Solid Earth::04.02. Exploration geophysics::04.02.02. Gravity methods ; 04. Solid Earth::04.03. Geodesy::04.03.05. Gravity variations ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 14
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    The borehole dilatometers network of Mt. Etna : a powerful tool to detect and infer volcano dynamics (2017)
    American Geophysical Union
    Details
    Publication Date: 2021-02-10
    Description: A network of four borehole dilatometers has been installed on Etna in two successive phases (2010–2011 and 2014). The borehole dilatometers are installed in holes drilled at depths usually greater than 100 m, and they measure the volumetric strain of the surrounding rock with a nominal precision up to 10^-11 in a wide frequency range (10^-7–25 Hz). Here we describe the characteristics of the network and the results of the in situ calibrations obtained after the installations by different methods. We illustrate short-term strain changes recorded during several lava fountains erupted by Etna during 2011–2013, and we also show signal changes recorded at all four stations during the lava fountain on 28 December 2014. Analytical and numerical computations constrained the eruptions source depth and also its volume change that is related to the magma volume emitted. Finally, we show the potential of the signal in the medium term to reveal strain changes related to different phases of the volcanic activity.
    Description: Published
    Description: 4655–4669
    Description: 1IT. Reti di monitoraggio e Osservazioni
    Description: JCR Journal
    Description: restricted
    Keywords: Etna volcano ; borehole strainmeters ; strain ; eruptions and lava fountains ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
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  • 15
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    Eruptive activity at Turrialba volcano (Costa Rica): Inferences from 3He/4He in fumarole gases and chemistry of the products ejected during 2014 and 2015 (2017)
    American Geophysical Union
    Details
    Publication Date: 2021-03-01
    Description: A new period of eruptive activity started at Turrialba volcano, Costa Rica, in 2010 after almost 150 years of quiescence. This activity has been characterized by sporadic explosions whose frequency clearly increased since October 2014. This study aimed to identify the mechanisms that triggered the resumption of this eruptive activity and characterize the evolution of the phenomena over the past 2 years. We integrate 3He/4He data available on fumarole gases collected in the summit area of Turrialba between 1999 and 2011 with new measurements made on samples collected between September 2014 and February 2016. The results of a petrological investigation of the products that erupted between October 2014 and May 2015 are also presented. We infer that the resumption of eruptive activity in 2010 was triggered by a replenishment of the plumbing system of Turrialba by a new batch of magma. This is supported by the increase in 3He/4He values observed since 2005 at the crater fumaroles and by comparable high values in September 2014, just before the onset of the new eruptive phase. The presence of a number of fresh and juvenile glassy shards in the erupted products increased between October 2014 and May 2015, suggesting the involvement of new magma with a composition similar to that erupted in 1864–1866. We conclude that the increase in 3He/4He at the summit fumaroles since October 2015 represents strong evidence of a new phase of magma replenishment, which implies that the level of activity remains high at the volcano.
    Description: Published
    Description: 3V. Proprietà dei magmi e dei prodotti vulcanici
    Description: 4V. Dinamica dei processi pre-eruttivi
    Description: 5V. Dinamica dei processi eruttivi e post-eruttivi
    Description: JCR Journal
    Keywords: Turrialba volcano ; eruptive activity ; 3He/4He ; fumarole gases ; glassy shards ; juvenile component ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.07. Tectonophysics::04.07.08. Volcanic arcs ; 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::04.08.08. Volcanic risk
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  • 16
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    How a complex basaltic volcanic system works: constraints from integrating seismic, geodetic and petrological data at Mt. Etna volcano during the July-August 2014 eruption (2017)
    American Geophysical Union
    Details
    Publication Date: 2021-04-07
    Description: Integrating geodetic, seismic, and petrological data for a recent eruptive episode at Mount Etna has enabled us to define the history of magma storage and transfer within the multilevel structure of the volcano, providing spatial and temporal constraints for magma movements before the eruption. Geodetic data related to the July–August 2014 activity provide evidence of a magma reservoir at ~4 km below sea level. This reservoir pressurized from late March 2014 and fed magmas that were then erupted from vents on the lower eastern flank of North-East Crater (NEC) and at New South-East Crater (NSEC) summit crater during the July eruptive activity. Magma drainage caused its depressurization since mid-July. Textural and microanalytical data obtained from plagioclase crystals indicate similar disequilibrium textures and compositions at the cores in lavas erupted at the base of NEC and NSEC, suggesting comparable deep histories of evolution and ascent. Conversely, the compositional differences observed at the crystal rims have been associated to distinct degassing styles during storage in a shallow magma reservoir. Seismic data have constrained depth for a shallow part of the plumbing system at 1–2 km above sea level. Timescales of magma storage and transfer have also been calculated through diffusion modeling of zoning in olivine crystals of the two systems. Our data reveal a common deep history of magmas from the two systems, which is consistent with a recharging phase by more mafic magma between late March and early June 2014. Later, the magma continued its crystallization under distinct chemical and physical conditions at shallower levels.
    Description: The petrological part of this study was supported by the FIR 2014 research grant to Marco Viccaro from the University of Catania (Italy), grant number 2F119B, title of the project “Dynamics of evolution, ascent and emplacement of basic magmas: case-studies from eruptive manifestations of Eastern Sicily”.
    Description: Published
    Description: 5659–5678
    Description: 2V. Dinamiche di unrest e scenari pre-eruttivi
    Description: 3V. Dinamiche e scenari eruttivi
    Description: JCR Journal
    Description: restricted
    Keywords: Petrology ; eruption ; GPS ; volcano seismology ; Etna ; 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::04.04. Geology::04.04.07. Rock geochemistry ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 17
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    Evidence of a shallow persistent magmatic reservoir from joint inversion of gravity and ground deformation data: The 25–26 October 2013 Etna lava fountaining event (2017)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: To evaluate the volcanic processes leading to the 25–26 October 2013 lava fountain at Mount Etna, we jointly investigated gravity, GPS, and DInSARmeasurements covering the late-June to early-November time interval. We used finite element modeling to infer a shallow magmatic reservoir which (i) inflated since July 2013, (ii) fed the volcanic activity at the summit craters during 25–26 October, and (iii) deflated due to magma drainage related to this volcanic activity. We suggested that this reservoir belongs to a shallow volume, which is located beneath the summit area and is replenished by magma rising from deep reservoirs and fed the short-term volcanic activity, representing a persistent shallow magmatic plumbing system of Etna. In addition, the model results show that there is a large discrepancy between the erupted and shallow reservoir deflation volumes, which could be reasonably attributable to a highly compressible volatile-rich magma.
    Description: Published
    Description: 3246–3253
    Description: 2V. Dinamiche di unrest e scenari pre-eruttivi
    Description: JCR Journal
    Description: open
    Keywords: Gravity and deformation signatures of the 26 October 2013 Mount Etna lava fountain ; Integrated finite element-based inversion of gravity and GPS data ; Inference on a highly compressible volatile-rich magma in the magmatic reservoir ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 18
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    New evidence of CO2 soil degassing anomalies on Piton de la Fournaise volcano and the link with volcano tectonic structures (2016)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: Piton de la Fournaise (PdF) is recognised as one of the world’s most active volcanoes in terms of eruptive frequency and the substantial quantity of lava produced. Yet, with the sole exception of rather modest intracrateric fumarole activity, this seems to be in contrast with an apparent absence of any type of natural fluid emission during periods of quiescence. Measurement campaigns were undertaken during a long-lasting quiescent period (2012-2014) and just after a short lived summit eruption (June 2014) in order to identify potential degassing areas in relation to the main structural features of the volcano (ex. rift zones) with the aim of developing a broader understanding of the geometry of the plumbing and degassing system. In order to assess the possible existence of anomalous soil CO2 flux, 513 measurements were taken along transects roughly orthogonal to the known tectonic lineaments crossing PdF edifice. In addition, 53 samples of gas for C isotope analysis were taken at measurement points that showed a relatively high CO2 concentration in the soil. CO2 flux values range from 10 to 1300 g m-2 d-1 while 13C are between -26.6 to -8‰. The results of our investigation clearly indicate that there is a strong spatial correlation between the anomalous high values of diffusive soil emissions and the main rift zones cutting the PdF massif and, moreover, that generally high soil CO2 fluxes show a d13C signature clearly related to a magmatic origin.
    Description: INSU (CNRS) and La Réunion Préfecture (Projet pour la quantification de l’aléa volcanique à La Réunion)
    Description: Published
    Description: 4388–4404
    Description: 2V. Dinamiche di unrest e scenari pre-eruttivi
    Description: JCR Journal
    Description: restricted
    Keywords: CO2 soil degassing anomalies at Piton de la Fournaise ; d13C magmatic signature ; Close link between anomalous CO2 degassing and the main seismotectonic structures ; 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::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 19
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    Asynchronous changes of CO2, H2 and He concentrations in soil gases: a theoretical model and experimental results (2016)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: This paper focuses on the chemical composition changes in soil gases through both a theoretical model and laboratory experiments. The model describes the one-dimensional mass transfer process, which is triggered by changes in the flux parameters of the system, and the time-dependent evolution of the composition of the soil gases as a function of i) the pristine gas mixture, ii) the diffusivity of the chemicals, and iii) the thickness of the transited medium. Carbon dioxide (CO2), hydrogen (H2), and helium (He) were used in a laboratory-scale flux simulator to investigate the evolution of the gas composition profile in an artificial soil of constant thickness. The agreement between the theoretical calculations and the experimental results supports the validity of the model. Our results indicate a good reproducibility of the transient changes in the concentrations of CO2, He, and H2 in CO2-rich gas mixtures that contain He and H2 as trace gases. Finally, the theoretical results were used to analyze the H2 and CO2 continuous monitoring data collected at Etna volcano in 2010
    Description: Published
    Description: 1565–1583
    Description: 2V. Dinamiche di unrest e scenari pre-eruttivi
    Description: 5V. Sorveglianza vulcanica ed emergenze
    Description: 1IT. Reti di monitoraggio e Osservazioni
    Description: JCR Journal
    Description: open
    Keywords: Soil gases ; Volcanic gas composition ; Hydrogen ; Carbon dioxide ; CO2 ; Helium ; 03. Hydrosphere::03.04. Chemical and biological::03.04.05. Gases ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 20
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    Very shallow dyke intrusion and potential slope failure imaged by ground deformation: The 28 December 2014 eruption on Mount Etna (2016)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: On 28 December 2014, eruptive activity resumed at Mount Etna with fire fountain activity feeding two lava flows on the eastern and southwestern upper flanks of the volcano. Unlike all previous summit activity, this eruption produced clear deformation at the summit of the volcano. GPS displacements and Sentinel-1A ascending interferogramswere calculated in order to image the ground deformation pattern accompanying the eruption. The displacements observed by GPS depict a local ground deformation pattern, affecting only the upperpart of the volcano.Despite snowcover onthe summit, differential interferometry synthetic aperture radar (DInSAR) data allowed obtainingmore detail onthe grounddeformation pattern on the upper eastern side of the volcano. Three-dimensional GPS displacements inversion located a very shallow NE-SW intrusion just beneath the New Southeast Crater. However, this model cannot justify all the deformation observed by DInSAR thus revealing a gravitational failure of the lava flow field
    Description: Published
    Description: 2727–2733
    Description: 3V. Dinamiche e scenari eruttivi
    Description: JCR Journal
    Description: restricted
    Keywords: Sentinel-1A interferogram details the ground deformation field ; GPS data are analyzed for modeling the dyke intrusion ; Data comparison highlights an incipient slope failure ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 21
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    High-speed imaging of Strombolian explosions: The ejection velocity of pyroclasts (2015)
    American Geophysical Union
    Details
    Publication Date: 2020-12-14
    Description: 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.
    Description: 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
    Description: Published
    Description: L02301
    Description: 3V. Dinamiche e scenari eruttivi
    Description: JCR Journal
    Description: open
    Keywords: 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
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  • 22
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    The stress field beneath a quiescent stratovolcano: The case of Mount Vesuvius (2015)
    American Geophysical Union
    Details
    Publication Date: 2020-12-15
    Description: We have analyzed a focal mechanism data set for Mount Vesuvius, consisting of 197 focal mechanisms of events recorded from 1999 to 2012. Using different approaches and a comparison between observations and numerical models, we have determined the spatial variations in the stress field beneath the volcano. The main results highlight the presence of two seismogenic volumes characterized by markedly different stress patterns. The two volumes are separated by a layer where the seismic strain release shows a significant decrease. Previous studies postulated the existence, at about the same depth, of a ductile layer allowing the spreading of the Mount Vesuvius edifice. We interpreted the difference in the stress pattern within the two volumes as the effect of a mechanical decoupling caused by the aforementioned ductile layer. The stress pattern in the top volume is dominated by a reverse faulting style, which agrees with the hypothesis of a seismicity driven by the spreading process. This agrees also with the persistent character of the seismicity located within this volume. Conversely, the stress field determined for the deep volume is consistent with a background regional field locally perturbed by the effects of the topography and of heterogeneities in the volcanic structure. Since the seismicity of the deep volume shows an intermittent behavior and has shown to be linked to geochemical variations in the fumaroles of the volcano, we hypothesize that it results from the effect of fluid injection episodes, possibly of magmatic origin, perturbing the pore pressure within the hydrothermal system.
    Description: Published
    Description: 1181–1199
    Description: 4T. Fisica dei terremoti e scenari cosismici
    Description: 2V. Dinamiche di unrest e scenari pre-eruttivi
    Description: 5V. Sorveglianza vulcanica ed emergenze
    Description: JCR Journal
    Description: restricted
    Keywords: vesuvius ; stress inversion ; focal mechanisms ; 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::04.07.05. Stress ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 23
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    The 2014 effusive eruption at Stromboli volcano (Italy): Inferences from soil CO2 flux and 3He/4He ratio in thermal waters (2015)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: A new eruption started at Stromboli on August 6, 2014, which had been preceded by 2 months of increased Strombolian activity and several lava overflows from the craters. The eruption was characterized by a lava effusion in Sciara del Fuoco from a fracture at 650 m a.s.l. that lasted until November 13–17. Here we present the first geochemical observations of this eruption, based on the soil CO2 flux in the summit area, and on 3He/4He ratios in the thermal waters near Stromboli village. We infer that this eruption was triggered by the gradual replenishment of the feeding system by a CO2- and 3He-rich magma at the end of 2013 and after June 2014, suggested by the increase in 3He/4He ratio before eruption, which reached its highest value since 2007. We thus infer that this eruption was unusual and we finally speculate on the evolutionary scenario of post eruption.
    Description: Published
    Description: 2235–2243
    Description: 2V. Dinamiche di unrest e scenari pre-eruttivi
    Description: 3V. Dinamiche e scenari eruttivi
    Description: 5V. Sorveglianza vulcanica ed emergenze
    Description: JCR Journal
    Description: restricted
    Keywords: Stromboli ; eruption ; soil CO2 flux ; 3He/4He ratio ; thermal waters ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 24
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    Stress rotations and the long-term weakness of the Median Tectonic Line and the Rokko-Awaji Segment. (2015)
    American Geophysical Union
    Details
    Publication Date: 2020-02-24
    Description: We used a field analysis of rock deformation microstructures and mesostructures to reconstruct the long-term orientation of stresses around two major active fault systems in Japan, the Median Tectonic Line and the Rokko-Awaji Segment. Our study reveals that the dextral slip of the two fault systems, active since the Plio-Quaternary, was preceded by fault normal extension in the Miocene and sinistral wrenching in the Paleogene. The two fault systems deviated the regional stress field at the kilometer scale in their vicinity during each of the three tectonic regimes. The largest deviation, found in the Plio-Quaternary, is a more fault normal rotation of the maximum horizontal stress to an angle of 79° with the fault strands, suggesting an extremely low shear stress on the Median Tectonic Line and the Rokko-Awaji Segment. Possible causes of this long-term stress perturbation include a nearly total release of shear stress during earthquakes, a low static friction coefficient, or lowelastic properties of the fault zones compared with the country rock. Independently of the preferred interpretation, the nearly fault normal orientation of the direction of maximum compression suggests that the mechanical properties of the fault zones are inadequate for the buildup of a pore fluid pressure sufficiently elevated to activate slip. The long-term weakness of the Median Tectonic Line and the Rokko-Awaji Segment may reside in low-friction/low-elasticity materials or dynamic weakening rather than in preearthquake fluid overpressures.
    Description: Published
    Description: 1900–1919
    Description: 2T. Tettonica attiva
    Description: JCR Journal
    Description: reserved
    Keywords: Kilometer-scale deviation of the regional stress fields around the two faults ; Rotations of the direction of maximum compression reveal fault weakness ; Fault weakness does not reside in static, preearthquake fluid overpressure ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
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  • 25
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    Reactivation of Stromboli’s summit craters at the end of the 2007 effusive eruption detected by thermal surveys and seismicity (2015)
    American Geophysical Union
    Details
    Publication Date: 2020-02-24
    Description: This work arises from the field observations made during the civil protection emergency period connected to the 2007 Stromboli eruption. We observed changes in the shallow feeding system of the volcano to which we give a volcanological interpretation and the relative implications. Here we describe the processes that occurred in the upper feeding system from the end of the 2007 effusive eruption on 3 April to the renewal of the strombolian explosive activity at the summit craters (30 June), interpreted using multidisciplinary data. We used thermal camera data collected both from helicopter and from a fixed station at 400 m to retrieve the evolving summit crater activity. These data, compared with seismic signals and published geochemical records, allowed us to detail the shifting of the degassing activity within the crater terrace from NE to SW, occurred between 15 and 25 April 2007 prior to the resumption of the strombolian activity. In particular, from mid-April, a gradual SW displacement in the maximum apparent temperatures was recorded at the vents within the summit craters, together with a change in the very long period location and confirmed by variations in geochemical indicators (CO2∕SO2 plume ratios and CO2 fluxes) from literature. The shallow feeding system experienced a major readjustment after the end of the effusive activity, determining variations in the pressure leakage of the source, slowly deepening and shifting toward SW. All these data, together with the framework supplied by previous structural surveys, allowed us to propose that the compaction of debris accumulated in the uppermost conduit by inward crater collapses, occurred in early March, produced the observed anomalies. At Stromboli, major morphology changes, taking place in the following years, were anticipated by these small and apparently minor processes occurred in the upper feeding system. Other studies are relating similar changes to modifications of the eruptive activity also at other open-conduit volcanoes, so we believe that it may be important to have a constant monitoring of these phenomena in order to better understand their shallow feeding systems.
    Description: This paper was partially supported by a grant to S.C. (Project INGV-DPC Paroxysm V2/03, 2008–2010) funded by the Istituto Nazionale di Geofisica e Vulcanologia and by the Italian Civil Protection.
    Description: Published
    Description: 7376–7395
    Description: 2V. Dinamiche di unrest e scenari pre-eruttivi
    Description: JCR Journal
    Description: restricted
    Keywords: Stromboli volcano ; thermal imaging ; multidisciplinary study ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 26
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    Long-term TIR imagery processing for spatiotemporal monitoring of surface thermal features in volcanic environment: A case study in the Campi Flegrei (Southern Italy) (2015)
    Wiley
    Details
    Publication Date: 2017-04-04
    Description: Different procedures were used to analyze a comprehensive time series of nighttime thermal infrared images acquired from October 2006 to June 2013 by a permanent station at Pisciarelli (Campi Flegrei, Italy). The methodologies were aimed at the detection and quantification of possible spatiotemporal changes in the ground-surface thermal features of an area affected by diffuse degassing. Long-term infrared time series images were processed without taking into account atmospheric conditions and emissivity estimations. The data obtained were compared with the trends of independent geophysical and geochemical parameters, which suggested that long-term temporal variations of the surface maximum temperatures were governed by the dynamics of the deeper hydrothermal system. Analogously, the dynamics of the shallow hydrothermal system are likely to control the short-period thermal oscillations that overlie the long-term thermal signals. The map of the yearly rates of temperature change shows temperature increases clustered in the thermal anomalous area of the infrared images, without evidence of modifications to the extension of the anomaly or of growth of new areas with significant thermal emission. This suggests that in the present state, the heat transfer is mainly due to hot gas emission through preexisting fractures and vents. Our data indicate that the comprehensive picture of the spatiotemporal evolution of the thermal features of the hydrothermal sites obtained by long-term infrared monitoring can provide useful information toward refining physical and conceptual models, as well as improving surveillance of active volcanoes.
    Description: The TIR monitoring system was partially funded by the 2000–2006 National Operating Programme and by the Italian Civil Protection Department in the framework of the 2004–2006 agreement with the Istituto Nazionale di Geofisica e Vulcanologia.
    Description: Published
    Description: 812–826
    Description: 2V. Dinamiche di unrest e scenari pre-eruttivi
    Description: 5V. Sorveglianza vulcanica ed emergenze
    Description: JCR Journal
    Description: restricted
    Keywords: Thermal Infrared Monitoring ; Campi Flegrei ; 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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  • 27
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    Highlights from a seismic broadband array on Stromboli (2015)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: An array of nine three-component broadband seismometers was deployed in two different configurations on Stromboli volcano. The analysis of the seismic wavefield related to volcanic explosions revealed some observations which offer a completely new insight into the internal dynamics of a volcano. These new observations are restricted to the low-frequency range below 1 Hz and underline, therefore, the superiority of broadband recordings over conventional short-period observations. Surprisingly simple wavelets indicate an initially contracting source mechanism. Gas-jets that could not be seen in a short-period seismic record at all, generate a clear dilatational wavelet in a broadband recording suggesting the same contracting source mechanism. The analysis of particle motion and seismic array techniques permits a location of the seismic source. We find low-frequency signals of 3s and 6s period that are not related to eruptions and do not share a common source with the eruption-related events. A video recording of visible volcanic activity at the crater region allows one to correlate precisely eruptive features with seismic signals.
    Description: Published
    Description: 749-752
    Description: 5V. Sorveglianza vulcanica ed emergenze
    Description: N/A or not JCR
    Description: restricted
    Keywords: Stromboli ; volcano seismology ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 28
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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
    Publication Date: 2017-04-04
    Description: 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.
    Description: 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
    Description: Published
    Description: 3096–3102
    Description: 3V. Dinamiche e scenari eruttivi
    Description: JCR Journal
    Description: restricted
    Keywords: 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
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  • 29
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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
    Publication Date: 2017-04-04
    Description: 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.
    Description: Published
    Description: 4153–4169
    Description: 2V. Dinamiche di unrest e scenari pre-eruttivi
    Description: JCR Journal
    Description: restricted
    Keywords: 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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  • 30
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    Sill intrusion as a source mechanism of unrest at volcanic calderas (2015)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: The interpretation of dynamic processes that occur in volcanic calderas is not simple. The ground deformations and the local seismicity, which in other volcanic contexts are usually regarded as precursors to eruption, in caldera environment in many cases are not followed by any eruption. We formulate a general hypothesis that can explain these behaviors. Our hypothesis is that the intrusion of a sill can be responsible for the dynamics observed during unrest at calderas. In order to investigate the reliability of this hypothesis, we developed a dynamic model of sill intrusion in a shallow volcanic environment. In our model, the sill, fed by a deeper magma reservoir, intrudes below a horizontal elastic plate, representing the overlying rocks, and expands with axisymmetric geometry. The model is based on the numerical solution of the equation for the elastic plate, coupled with a Navier-Stokes equation for simulating the dynamics of the sill intrusion. We performed a number of simulations, with the objective of showing the main features of the model. In the experiments, when the feeding process stops, the vertical movement reverses its trend and the area of maximum uplift undergoes subsidence. Under certain conditions the subsidence can occur even during the intrusion of the sill. The stress field produced by the intrusion is mainly concentrated in a circular zone that follows the sill intrusion front. The features predicted by the model are consistent with many observations carried out on different calderas as reported in the scientific literature.
    Description: Published
    Description: 3986–4000
    Description: 2V. Dinamiche di unrest e scenari pre-eruttivi
    Description: 3V. Dinamiche e scenari eruttivi
    Description: 5V. Sorveglianza vulcanica ed emergenze
    Description: JCR Journal
    Description: restricted
    Keywords: sill intrusion ; caldera ; volcano geodesy ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.05. Mathematical geophysics::05.05.99. General or miscellaneous
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  • 31
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    The 2010 ash emissions at the summit craters of Mt Etna: Relationship with seismo-acoustic signals (2015)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: Mt Etna volcano (Italy) typically generates lava fountains and Strombolian eruptions from the summit craters, producing significant emissions of tephra which may cause moderate to high impact both in the atmosphere and on the ground. However, we have also witnessed a number of minor ash emissions that, although far less powerful, may pose considerable volcanic hazards. In this paper, we deal with three ash emissions occurring in 2010 (8 April at Southeast Crater, 25 August at Bocca Nuova, and 14–15 November at Northeast Crater), correlating their volcanological features with the associated seismoacoustic signals. We provide details regarding the chronology, eruption column, dispersal of the deposit, and texture (grain size, componentry and morphology) of the emitted ash. Each eruptive episode has also been characterized by means of seismo-acoustic analyses evaluating the volcanic acoustic-seismic ratio (VASR). Furthermore, the source of volcanic tremor recorded from March to December 2010 was localized. The joint volcanological and seismo-acoustic analyses allowed distinguishing two main kinds of ash emissions: types a (8 April and 25 August) and b (14–15 November). Regarding the former, the accumulation of gas below a dense cap rock obstructing the conduit vent, giving rise, with the uncorking, to impulsive explosivity, was hypothesized. The latter type instead is characterized by a longer-lasting and less explosivity, likely due to the existence of open conduit conditions. Therefore, type b ash emissions are less hazardous than type a. This simple model, regarding minor explosive activity, may constitute a starting point to assess the volcanic risk from unexpected explosions.
    Description: Published
    Description: 51-70
    Description: 3V. Dinamiche e scenari eruttivi
    Description: JCR Journal
    Description: reserved
    Keywords: Mt Etna ; seismo-acoustic signals ; ash emissions ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 32
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    Multiparametric study of the February-April 2013 paroxysmal phase of Mt. Etna New South-East crater (2015)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: Between January 2011 and April 2013, Mt. Etna's eruptive activity consisted of episodic intra-crater strombolian explosions and paroxysms from Bocca Nuova, Voragine, and the New South-East (NSEC) summit craters, respectively. Eruptions from NSEC consisted of initial increasing strombolian activity and lava flow output, passing to short-lasting lava fountaining. In this study we present seismic, infrasound, radiometric, plume SO2 and HCl fluxes and geodetic data collected by the INGV monitoring system between May 2012 and April 2013. The multi-parametric approach enabled characterization of NSEC eruptive activity at both daily and monthly time scales and tracking of magma movement within Mt. Etna's plumbing system. While seismic, infrasound and radiometric signals give insight on the energy and features of the 13 paroxysms fed by NSEC, SO2 and halogen fluxes shed light on the likely mechanisms triggering the eruptive phenomena. GPS data provided clear evidence of pressurization of Mt. Etna's plumbing system from May 2012 to middle February 2013 and depressurization during the February-April 2013 eruptive activity. Taking into account geochemical data, we propose that the paroxysms' sequence represented the climax of a waxing-waning phase of degassing that had started as early as December 2012, and eventually ended in April 2013. Integration of the multidisciplinary observations suggests that the February-April 2013 eruptive activity reflects a phase of release of a volatile-rich batch of magma that had been stored in the shallow volcano plumbing system at least four months before, and with the majority of gas released between February and March 2013. This article is protected by copyright. All rights reserved.
    Description: European FP7 MED-SUV (MEditerranean SUpersite Volcanoes). Grant Number: 308665 European Research Council European FP7 (FP/2007-2013)/ERC. Grant Number: 279802 SIGMA (Sistema Integrato di sensori in ambiente cloud per la Gestione Multirischio Avanzata)
    Description: Published
    Description: 1932–1949
    Description: 3V. Dinamiche e scenari eruttivi
    Description: JCR Journal
    Description: restricted
    Keywords: Mt. Etna ; paroxysmal activity ; SO2 and HCl fluxes ; infrasound and seismic signals ; radiometry ; ground deformation ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 33
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    Experimental investigation of the aggregation-disaggregation of colliding volcanic ash particles in turbulent, low-humidity suspensions (2015)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: We present the results of laboratory experiments on the aggregation and disaggregation of colliding volcanic ash particles. Ash particles of different composition and size 〈90 µm were held in turbulent suspension and filmed in high speed while colliding, aggregating, and disaggregating, forming a growing layer of electrostatically bound particles along a vertical plate. At room conditions and regardless of composition, 60–80% of the colliding particles smaller than 32 µm remained aggregated. In contrast, aggregation of particles larger than 63 µm was negligible, and, when a layer formed, periods when disaggregation (mainly by collisions or drag) exceeded aggregation occurred twice as frequently than for smaller particles. An empirical relationship linking the aggregation index, i.e., the effective fraction of aggregated particles surviving disaggregation, to the mean particle collision kinetic energy is provided. Our results have potential implications on the dynamics of volcanic plumes and ash mobility in the environment.
    Description: INGV-DPC project V1 “Probabilistic evaluation of volcanic hazard”; EU Seventh Programme FP7 “MED-SUV” grant agreement 308665
    Description: Published
    Description: 1068–1075
    Description: 3V. Dinamiche e scenari eruttivi
    Description: 2IT. Laboratori sperimentali e analitici
    Description: JCR Journal
    Description: restricted
    Keywords: volcanic ash ; disaggregation ; experimental modeling ; volcanic plumes ; aggregation processes ; colliding particles ; sticking rate ; 01. Atmosphere::01.01. Atmosphere::01.01.07. Volcanic effects ; 04. Solid Earth::04.08. Volcanology::04.08.02. Experimental volcanism ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
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  • 34
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    Linked frequency and intensity of persistent volcanic activity at Stromboli (Italy) (2015)
    American Geophysical Union
    Details
    Publication Date: 2021-12-15
    Description: Relationships between frequency and intensity of volcanic eruptions are actively sought by geophysicists for both monitoring and research purposes. By analyzing surveillance videos of persistent volcanic activity at Stromboli (Italy), we derived the frequency and jet height of 〉4000 explosions that occurred in 72 h-long time windows sampled yearly from 2005 to 2009. We found a positive relationship linking explosion frequency and jet height (linked to eruption intensity) when averaging the two parameters over time intervals from hours to days, with a stronger correlation for longer intervals. We interpret this behavior as the response of the magmatic system to variable influx of magma and gas at depth, increased flux at depth causing more frequent and stronger explosions at the surface. This relationship entails concurrent control of source processes over explosion frequency and intensity, directly impacting modeling of explosion sources at persistently active volcanoes in general and hazard assessment at Stromboli in particular.
    Description: DPC-INGV Project V2 “Paroxysm”
    Description: Published
    Description: 1–5
    Description: 3V. Dinamiche e scenari eruttivi
    Description: JCR Journal
    Description: reserved
    Keywords: Stromboli ; Strombolian frequency ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 35
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    Active alkaline traps to determine acidic-gas ratios in volcanic plumes: Sampling techniques and analytical methods (2015)
    American Geophysical Union
    Details
    Publication Date: 2023-01-19
    Description: In situ measurements have been the basis for monitoring volcanic gas emissions for many years and—being complemented by remote sensing techniques—still play an important role to date. Concerning in situ techniques for sampling a dilute plume, an increase in accuracy and a reduction of detection limits are still necessary for most gases (e.g., CO2, SO2, HCl, HF, HBr, HI). In this work, the Raschig-Tube technique (RT) is modified and utilized for application on volcanic plumes. The theoretical and experimental absorption properties of the RT and the Drechsel bottle (DB) setups are characterized and both are applied simultaneously to the well-established Filter packs technique (FP) in the field (on Stromboli Island and Mount Etna). The comparison points out that FPs are the most practical to apply but the results are errorprone compared to RT and DB, whereas the RT results in up to 13 times higher analyte concentrations than the DB in the same sampling time. An optimization of the analytical procedure, including sample pretreatment and analysis by titration, Ion Chromatography, and Inductively Coupled Plasma Mass Spectrometry, led to a comprehensive data set covering a wide range of compounds. In particular, less abundant species were quantified more accurately and iodine was detected for the first time in Stromboli’s plume. Simultaneously applying Multiaxis Differential Optical Absorption Spectroscopy (MAX-DOAS) the chemical transformation of emitted bromide into bromine monoxide (BrO) from Stromboli and Etna was determined to 3–6% and 7%, respectively, within less than 5 min after the gas release from the active vents.
    Description: Published
    Description: 2797–2820
    Description: 5V. Sorveglianza vulcanica ed emergenze
    Description: JCR Journal
    Description: restricted
    Keywords: plume ; volcano ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 36
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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
    Publication Date: 2020-02-24
    Description: 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.
    Description: Published
    Description: 2382–2389
    Description: 2V. Dinamiche di unrest e scenari pre-eruttivi
    Description: JCR Journal
    Description: restricted
    Keywords: 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)
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  • 37
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    The coupling between very long period seismic events, volcanic tremor, and degassing rates at Mount Etna volcano (2014)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: From December 2005 to January 2006, an anomalous degassing episode was observed at Mount Etna, well-correlated with an increase in volcanic tremor, and in the almost complete absence of eruptive activity. In the same period, more than 10,000 very long period (VLP) events were detected. Through moment tensor inversion analyses of the VLP pulses, we obtained quantitative estimates of the volumetric variations associated with these events. This allowed a quantitative investigation of the relationship between VLP seismic activity, volcanic tremor, and gas emission rate at Mount Etna. We found a statistically significant positive correlation between SO2 gas flux and volcanic tremor, suggesting that tremor amplitude can be used as a first-order proxy for the background degassing activity of the volcano. VLP volumetric changes and SO2 gas flux are correlated only for the last part of our observations, following a slight change in the VLP source depth. We calculate that the gas associated with VLP signal genesis contributed less than 5% of the total gas emission. The existence of a linear correlation between VLP and degassing activities indicates a general relationship between these two processes. The effectiveness of such coupling appears to depend upon the particular location of the VLP source, suggesting that conduit geometry might play a significant role in the VLP-generating process. These results are the first report on Mount Etna of a quantitative relationship between the amounts of gas emissions directly estimated through instrumental flux measurements and the quantities of gas mass inferred in the VLP source inversion.
    Description: Published
    Description: 4910-4921
    Description: 2V. Dinamiche di unrest e scenari pre-eruttivi
    Description: JCR Journal
    Description: restricted
    Keywords: Very Long Period seismicity ; UV scanners network ; Etna Volcano ; volcano monitoring ; 04. Solid Earth::04.02. Exploration geophysics::04.02.06. Seismic methods ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 38
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    Eruptive processes leading to the most explosive lava fountain at Etna volcano: The 23 November 2013 episode (2014)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: The 23 November 2013 lava fountain at Etna volcano was the most explosive of the last 44 episodes that have occurred at Etna in 2011–2013. We infer the total magma volume erupted by thermal images analysis and show that it was characterized by a very high time-averaged-discharge-rate (TADR) of ~360m3 s 1, having erupted ~1.6 × 106m3 of dense-rock equivalent magma volume in just 45 min, which is more than 3 times the TADR observed during previous episodes. Two borehole dilatometers confirmed the eruption dynamics inferred from the thermal images. When compared to the other lava fountains, this episode can be considered as the explosive end-member. However, the erupted volume was still comparable to the other lava fountain events. We interpret that the 23 November explosive end-member event was caused by more primitive and gas-rich magma entering the system, as demonstrated by the exceptional height reached by the lava fountain.
    Description: Published
    Description: 4912–4919
    Description: 3V. Dinamiche e scenari eruttivi
    Description: JCR Journal
    Description: restricted
    Keywords: Etna eruption ; paroxysmal explosive eruption ; lava fountain ; strainmeters ; lava fountain volume ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 39
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    Multidisciplinary Approach Yields Insight into Mt. Etna 2001 Eruption (2014)
    American Geophysical Union
    Details
    Publication Date: 2020-02-24
    Description: On July 17,2001, lava began pouring down the slopes of Mt. Etna in Sicily signaling the start of the volcano's first flank eruption in nearly 10 years. Etna typically experiences long periods of explosive and effusive activity at the summit, which lies 3350 m a.s.l., interspersed with shorter flank eruptions. During the latter, large volumes of lava can threaten local populations. The Catania Section of the Istituto Nazionale di Geofisica e Vulcanologia (INGV) routinely monitors the volcano with an array of integrated multidisciplinary techniques. During the 2001 flank eruption, researchers obtained the deepest insight yet into the mechanisms that control this fascinating volcano. In particular, by studying ground deformation, seismicity, gravity changes, and geomagnetism, researchers were able to forecast 3 to 4 days in advance the intrusion of a new feeder dike in the upper part of the volcano and follow the propagation of dike emplacement and fissure opening, as well as estimate the volume of the intrusion. During the eruption, volcanology gas geochemistry and petrology were used to distinguish two different magmas erupting at the same time from both this new feeder dike and the summit feeding system, which has been active since January 2001. Effusion rate measurements and thermal mapping of the flow field provided insight into the maximum length the lava flow could reach from the lower vent, and researchers were able to follow the process of tube formation along this flow. The previous flank eruption on Etna occurred between 1991 and 1993, when 235 million of lava poured from within the Valle del Bove (VDB) and formed a lava flow field over 8.5 km long that threatened the town of Zafferana. Since then, eruptive activity at Etna has been restricted to the summit area. A progressive increase in the activity occurred between June 1998 and February 1999, with a succession of 21 paroxysmal episodes from the Southeast Cone (SEC). Then, on February 1999, a fire fountain episode from the SEC indicated the start of the 1999 summit eruption, which produced two lava flow fields. During 2000, there were 66 fire fountain events from the SEC accompanied by small lava flows. Lava flow emission started again from the north base of the SEC in January 2001, and on May 9,2001, small fire fountaining episodes were observed on the summit and northern flank of the SEC.This activity gradually increased in frequency and intensity before the 2001 flank eruption.
    Description: Published
    Description: 653-656
    Description: 3V. Dinamiche e scenari eruttivi
    Description: N/A or not JCR
    Description: restricted
    Keywords: Etna eruption ; volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 40
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    New insights on volcanic and tectonic structures of the southern Tyrrhenian (Italy) from marine and land seismic data (2013)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: We present results from the first crustal seismic tomography for the southern Tyrrhenian area, which includes ocean bottom seismometer (OBS) data and a bathymetry correction. This area comprises Mt. Etna, the Aeolian Islands, and many volcanic seamounts, including the Marsili Seamount. The seismicity distribution in the area depends on the complex interaction between tectonics and volcanism. The 3-D velocity model presented in this study is obtained by the inversion of P wave arrival times from crustal earthquakes. We integrate travel time data recorded by an OBS network (Tyrrhenian Deep Sea Experiment), the SN-1 seafloor observatory, and the land network. Our model shows a high correlation between the P wave anomaly distribution and seismic and volcanic structures. Two main low-velocity anomalies underlie the central Aeolian Islands and Mt. Etna. The two volumes, which are related to the well-known active volcanism, are separated and located at different depths. This finding, in agreement with structural, petrography, and GPS data from literature, confirms the independence of the two systems. The strongest negative anomaly is found below Mt. Etna at the base of the crust, and we associate it with the deep feeding system of the volcano. We infer that most of the seismicity is generated in brittle rock volumes that are affected by the action of hot fluids under high pressure due to the active volcanism in the area. Lateral changes of velocity are related to a transition from the western to the central Aeolian Islands and to the passage from continental crust to the Tyrrhenian oceanic uppermost mantle.
    Description: Published
    Description: 3703–3719
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: open
    Keywords: ocean bottom seismometers ; southern Tyrrhenian Sea ; seismic tomography ; Aeolian Islands ; Etna ; oceanic continental crust ; 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::04.07. Tectonophysics::04.07.04. Plate boundaries, motion, and tectonics ; 04. Solid Earth::04.07. Tectonophysics::04.07.06. Subduction related processes ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 41
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    The 4D imaging of the source of ground deformation at Campi Flegrei caldera (southern Italy) (2013)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: We have applied a tomographic imaging technique to the inversion of a DInSAR data set at Campi Flegrei caldera. This technique allowed us to determine the temporal and spatial distribution of volumetric strain sources up to 5 km depth. Results have shown complex spatial and temporal patterns, identifying important features that were not noticed before. The first result is the observation of positive strain sources (expansion) migrating upward (in 2000 and 2006). We have interpreted them as hot fluid batches injected at the bottom of the geothermal reservoir, migrating upward and reaching the surface. Furthermore we have identified an injection episode (in 1997), which was not recognized before. This batch did not reach the surface and probably dissipated by diffusion and lateral advection without producing significant ground uplift. The injection of fluid batches does not occur at the center of the caldera, but along its borders. The three identified injection episodes (in 1997, 2000 and 2006) occur in different points. In 2000 and 2006, the injected fluids migrated, subsequently, toward the center of the caldera. Our findings agrees with results of other geophysical and geochemical studies. These results suggest a new framework for the modeling of Campi Flegrei geothermal system and for the interpretation of data recorded by the multiparametric monitoring networks on the caldera.
    Description: Published
    Description: B08209
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: restricted
    Keywords: Campi Flegrei ; tomographic imaging ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 42
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    Separating the thermal fingerprints of lava flows and simultaneous lava fountaining using ground-based thermal camera and SEVIRI measurements (2013)
    American Geophysical Union
    Details
    Publication Date: 2020-02-24
    Description: During effusive eruptions, thermal satellite monitoring has proved well suited to map the thermal flux from lava flows. However, during lava fountaining events, thermal contributions from active flows and from the fountain itself cannot be separated in low resolution satellite data. Here using photogrammetry and atmospheric modeling techniques, we compare radiance estimates from long-range ground-based thermal camera data (from which the fountain can be excluded) with those from SEVIRI satellite images for a fountaining event at Mount Etna (12 August 2011). The radiant heat flux determined from the ground-based camera showed similar behavior to values retrieved from Spinning Enhanced Visible and Infrared Imager (SEVIRI); thus the SEVIRI signal is interpreted to be dominated by the lava flows, with minimal contribution from the fountain. Furthermore, by modeling the cooling phase of each pixel inundated by lava, the mean thickness and lava volume (~2.4 × 106 m3) derived from camera images are comparable with those calculated from SEVIRI (~2.8 × 106 m3).
    Description: Published
    Description: 5058–5063
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: JCR Journal
    Description: restricted
    Keywords: Etna ; satellite ; thermal monitoring ; SEVIRI ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 43
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    Thermal insights into the dynamics of Nyiragongo lava lake from ground and satellite measurements (2013)
    American Geophysical Union
    Details
    Publication Date: 2020-02-24
    Description: We present new insights into the short- and long-term thermal activity of the Nyiragongo lava lake by ground-based and satellite infrared thermal imagery recorded in the first half of 2012. This is the very first time in which FLIR camera and SEVIRI data have been compared at this volcano. Maximum temperatures recorded at the molten lava were of ~1180 K, whereas the lake skin remained always below ~734 K in areas far from the upwelling zone and below ~843 K in those proximal to the source region. Ground-based imagery yielded mean radiative power values between ~0.80 and 1.10 GW. Consistently, satellite observations showed similar mean values of 1.10 GW. Overall the thermal activity of the lava lake was quite variable along the three days of field measurements at both daily and intradaily scale. SEVIRI radiative power values retrieved for the January–June 2012 period revealed fluctuations within the same variability range suggesting that no significant changes of the lava lake area had occurred over the six months. Comparison with previous radiative power estimates showed that our data well agree with the general increasing trend recorded since the reappearance of the lava lake after the last flank eruption in 2002.
    Description: This study was funded by Zanskar Producciones, Cabildo Insular de Tenerife, and the Instituto Volcanológico de Canarias. We are grateful to EUMETSAT for providing us SEVIRI data and to NASA for the Landsat 7 image. Letizia Spampinato thanks Dr S. Giammanco for funding her research activity on the VIGOR project.
    Description: Published
    Description: 5771–5784
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: JCR Journal
    Description: restricted
    Keywords: thermal imagery ; satellite thermal images ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 44
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    Earthquake sound perception (2013)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: Sound is an effect produced by almost all earthquakes. Using a web-based questionnaire on earthquake effects that included questions relating to seismic sound, we collected 77,000 responses for recent shallow Italian earthquakes. An analysis of audibility attenuation indicated that the decrease of the percentage of respondents hearing the sound was proportional to the logarithm of the epicentral distance and linearly dependent on earthquake magnitude, in accordance with the behavior of ground displacement. Even if this result was based on Italian data, qualitative agreement with the results of theoretical displacement, and of a similar study based on French seismicity suggests wider validity. We also found that, given earthquake magnitude, audibility increased together with the observed macroseismic intensity, leading to the possibility of accounting for sound audibility in intensity assessment. Magnitude influenced this behavior, making small events easier to recognize, as suggested by their frequency content.
    Description: Published
    Description: L24301
    Description: 1.11. TTC - Osservazioni e monitoraggio macrosismico del territorio nazionale
    Description: JCR Journal
    Description: open
    Keywords: earthquake sound ; questionnaires ; macroseismic intensity ; ground displacement ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
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  • 45
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    A land-to-ocean perspective on the magnitude, source and implication of DIC flux from major Arctic rivers to the Arctic Ocean (2013)
    American Geophysical Union
    Details
    Publication Date: 2022-05-25
    Description: 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 Global Biogeochemical Cycles 26 (2012): GB4018, doi:10.1029/2011GB004192.
    Description: A series of seasonally distributed measurements from the six largest Arctic rivers (the Ob', Yenisey, Lena, Kolyma, Yukon and Mackenzie) was used to examine the magnitude and significance of Arctic riverine DIC flux to larger scale C dynamics within the Arctic system. DIC concentration showed considerable, and synchronous, seasonal variation across these six large Arctic rivers, which have an estimated combined annual DIC flux of 30 Tg C yr−1. By examining the relationship between DIC flux and landscape variables known to regulate riverine DIC, we extrapolate to a DIC flux of 57 ± 9.9 Tg C yr−1for the full pan-arctic basin, and show that DIC export increases with runoff, the extent of carbonate rocks and glacial coverage, but decreases with permafrost extent. This pan-arctic riverine DIC estimate represents 13–15% of the total global DIC flux. The annual flux of selected ions (HCO3−, Na+, Ca2+, Mg2+, Sr2+, and Cl−) from the six largest Arctic rivers confirms that chemical weathering is dominated by inputs from carbonate rocks in the North American watersheds, but points to a more important role for silicate rocks in Siberian watersheds. In the coastal ocean, river water-induced decreases in aragonite saturation (i.e., an ocean acidification effect) appears to be much more pronounced in Siberia than in the North American Arctic, and stronger in the winter and spring than in the late summer. Accounting for seasonal variation in the flux of DIC and other major ions gives a much clearer understanding of the importance of riverine DIC within the broader pan-arctic C cycle.
    Description: Funding for this work was provided through NSF-OPP-0229302 and NSF-OPP-0732985. Additional support to SET was provided by an NSERC Postdoctoral Fellowship.
    Description: 2013-06-14
    Keywords: Arctic ; Dissolved inorganic carbon ; Ocean acidification ; Permafrost ; River biogeochemistry ; Weathering
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 46
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    A year of lava fountaining at Etna: Volumes from SEVIRI (2012)
    American Geophysical Union
    Details
    Publication Date: 2021-06-09
    Description: We present a new method that uses cooling curves, apparent in high temporal resolution thermal data acquired by geostationary sensors, to estimate erupted volumes and mean output rates during short lava fountaining events. The 15 minute temporal resolution of the data allows phases of waxing and peak activity to be identified during short (150-to- 810 minute-long) events. Cooling curves, which decay over 8-to-21 hour-periods following the fountaining event, can also be identified. Application to 19 fountaining events recorded at Etna by MSG’s SEVIRI sensor between 10 January 2011 and 9 January 2012, yields a total erupted dense rock lava volume of 28 106 m3, with a maximum intensity of 227 m3 s 1 being obtained for the 12 August 2011 event. The timeaveraged output over the year was 0.9 m3 s 1, this being the same as the rate that has characterized Etna’s effusive activity for the last 40 years.
    Description: We are grateful to EUMETSAT for SEVIRI data.
    Description: Published
    Description: L06305
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: JCR Journal
    Description: restricted
    Keywords: satellite ; lava fountains ; Etna ; erupted volume ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 47
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    Dynamics of a lava fountain revealed by geophysical, geochemical and thermal satellite measurements: The case of the 10 April 2011 Mt Etna eruption (2012)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: Geophysical (tilt, seismic tremor and gravity signals), geochemical (crater SO2 flux) and infrared satellite measurements are presented and discussed to track the temporal evolution of the lava fountain episode occurring at Mt Etna volcano on 10 April 2011. The multi-disciplinary approach provides insight into a gas-rich magma source trapped in a shallow storage zone inside the volcano edifice. This generated the fast ascending gas-magma dispersed flow feeding the lava fountain and causing the depressurization of a deeper magma storage. Satellite thermal data allowed estimation of the amount of erupted lava, which, summed to the tephra volume, yielded a total volume of erupted products of about 1 106 m3. Thanks to the daylight occurrence of this eruptive episode, the SO2 emission rate was also estimated, showing a degassing cycle reaching a peak of 15,000 Mg d 1 with a mean daily value of 5,700 Mg d 1. The SO2 data from the previous fountain episode on 17–18 February to 10 April 2011, yielded a cumulative degassed magma volume of about 10.5 106 m3, indicating a ratio of roughly 10:1 between degassed and erupted volumes. This volumetric balance, differently from those previously estimated during different styles of volcanic activities with long-term (years) recharging periods and middle-term (weeks to months) effusive eruptions, points toward the predominant role played by the gas phase in generating and driving this lava fountain episode.
    Description: Published
    Description: L24307
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: restricted
    Keywords: Mt. Etna ; lava fountain ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 48
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    How do volcanic rift zones relate to flank instability? Evidence from collapsing rifts at Etna (2012)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: 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.
    Description: 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).
    Description: Published
    Description: L20311
    Description: 1.3. TTC - Sorveglianza geodetica delle aree vulcaniche attive
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 1.10. TTC - Telerilevamento
    Description: 3.2. Tettonica attiva
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: 3.6. Fisica del vulcanismo
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: restricted
    Keywords: 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
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  • 49
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    Source mechanism of long-period events recorded by a high-density seismic network during the 2008 eruption on Mount Etna (2012)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: One hundred twenty-nine long-period (LP) events, divided into two families of similar events, were recorded by the 50 stations deployed on Mount Etna in the second half of June 2008. During this period lava was flowing from a lateral fracture after a summit Strombolian eruption. In order to understand the mechanisms of these events, we perform moment tensor inversions. Inversions are initially kept unconstrained to estimate the most likely mechanism. Numerical tests show that unconstrained inversion leads to reliable moment tensor solutions because of the close proximity of numerous stations to the source positions. However, single forces cannot be accurately determined as they are very sensitive to uncertainties in the velocity model. Constrained inversions for a crack, a pipe or an explosion then allow us to accurately determine the structural orientations of the source mechanisms. Both numerical tests and LP event inversions emphasise the importance of using stations located as close as possible to the source. Inversions for both families show mechanisms with a strong volumetric component. These events are most likely generated by cracks striking SW–NE for both families and dipping 70° SE (family 1) and 50° NW (family 2). For family 1 events, the crack geometry is nearly orthogonal to the dikelike structure along which events are located, while for family 2 the location gave two pipelike bodies that belong to the same plane as the crack mechanism. The orientations of the cracks are consistent with local tectonics, which shows a SW–NE weakness direction. The LP events appear to be a response to the lava fountain occurring on 10 May 2008 as opposed to the flank lava flow.
    Description: Published
    Description: B01304
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: 3.1. Fisica dei terremoti
    Description: JCR Journal
    Description: reserved
    Keywords: Etna Volcano ; long-period events ; source mechanism ; location ; plumbing systems ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 50
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    Narrow-band, transient signals in Central Apennines, Italy: hints for underground fluid migration? (2012)
    Wiley
    Details
    Publication Date: 2017-04-04
    Description: In this paper we investigate nature and properties of narrow-band, transient seismic signals observed by a temporary array deployed in the Val Tiberina area (central Apennines, Italy). These signals are characterized by spindle-shaped, harmonic waveforms with no clear S-wave arrivals. The first portion of the seismograms exhibits a main frequency peak centred at 4.5 Hz, while the spectrum of the slowly decaying coda is peaked at about 2 Hz. Events discrimination is performed using a matched-filtering technique, resulting in a set of 2466 detections spanning the 2010 January–March time interval. From a plane-wave-fitting procedure, we estimate the kinematic properties of signals pertaining to a cluster of similar events. The repetition of measurements over a large number of precisely aligned seismograms allows for obtaining a robust statistics of horizontal slownesses and propagation azimuths associated with the early portion of the waveforms. The P-wave arrival exhibits horizontal slownesses around 0.1 s km−1, thus suggesting waves impinging at the array almost vertically. Separately, we use traveltimes measured at a sparse network to derive independent constraints on epicentral location. Ray parameters and azimuths are calibrated using slowness measurements from a local, well-located earthquake. After this correction, the joint solution from traveltime inversion and array analysis indicates a source region spanning the 1–3 km depth interval. Considerations related to the source depth and energy, and the occurrence rate which is not related to the daily and weekly working cycles, play against a surface, artificial source. Instead, the close resemblance of these signals to those commonly observed in volcanic environments suggest a source mechanism related to the resonance of a fluid–filled fracture, likely associated with instabilities in the flux of pressurized CO2.
    Description: Published
    Description: 918-928
    Description: 1.1. TTC - Monitoraggio sismico del territorio nazionale
    Description: JCR Journal
    Description: reserved
    Keywords: Fracture and flow ; Earthquake source observations ; Interface waves ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
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  • 51
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    Ground deformations and volcanic processes as imaged by CGPS data at Mt. Etna (Italy) between 2003 and 2008 (2012)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: We analyze the kinematic and crustal deformations of Mt. Etna from 2003 to 2008 as imaged by the Mt. Etna continuous GPS (CGPS) network (Etna@net). Through a careful analysis of GPS time series, six coherent phases of crustal deformations have been identified, three inflation phases and three deflation phases, superimposed on a major inflation of the volcanic edifice since 2001. The inversions of GPS velocities have enabled: 1) a better understanding of the evolution of the volcanic sources acting beneath the volcano; 2) analysis of the strain rate patterns; and 3) a delineation of potential coupling between volcanic sources and the observed ground deformations. The modelling of the pressure sources has shown a separation between inflation and deflation sources. The deflation sources show an upward migration, from 5.5 toward 2.0 km (b.s.l.), while the inflation sources are located within 5.5 and 4.0 km (b.s.l.). Our results indicate that the kinematic and ground deformations of the mid-upper eastern flank are driven by the interplay between the effect of the magmatic sources and a south-eastward motion. Furthermore, clockwise rotations have been detected that prevailed over the eastern motion of the flank during the inflation phase preceding the 2004-2005 and 2006 eruptions. Finally, the accordance between the higher geodetic shear strain rates and the area with the highest seismic energy release shows that measured geodetic shear strain rates can provide useful information on the potential occurrence of seismic activity.
    Description: Osservatorio Etneo, Istituto Nazionale di Geofisica e Vulcanologia,Catania, Italy. Department of Geosciences, State University of New York at Stony Brook, Stony Brook, New York, USA.
    Description: Published
    Description: B07208
    Description: 1.3. TTC - Sorveglianza geodetica delle aree vulcaniche attive
    Description: JCR Journal
    Description: restricted
    Keywords: Mt. Etna ground deformations ; Volcano monitoring ; Strain rate analysis ; Volcanic source modelling ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 52
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    A conceptual model of an Arctic sea (2012)
    American Geophysical Union
    Details
    Publication Date: 2022-05-25
    Description: 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 Journal of Geophysical Research 117 (2012): C06010, doi:10.1029/2011JC007652.
    Description: We propose a conceptual model for an Arctic sea that is driven by river runoff, atmospheric fluxes, sea ice melt/growth, and winds. The model domain is divided into two areas, the interior and boundary regions, that are coupled through Ekman and eddy fluxes of buoyancy. The model is applied to Hudson and James Bays (HJB, a large inland basin in northeastern Canada) for the period 1979–2007. Several yearlong records from instruments moored within HJB show that the model results are consistent with the real system. The model notably reproduces the seasonal migration of the halocline, the baroclinic boundary current, spatial variability of freshwater content, and the fall maximum in freshwater export. The simulations clarify the important differences in the freshwater balance of the western and eastern sides of HJB. The significant role played by the boundary current in the freshwater budget of the system, and its sensitivity to the wind-forcing, are also highlighted by the simulations and new data analyses. We conclude that the model proposed is useful for the interpretation of observed data from Arctic seas and model outputs from more complex coupled/climate models.
    Description: We thank NSERC and the Canada Research Chairs program for funding. FS acknowledges support from NSF OCE–0927797 and ONR N00014-08-10490.
    Description: 2012-12-20
    Keywords: Arctic ; Models ; Sea ice
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 53
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    Landscape-level controls on dissolved carbon flux from diverse catchments of the circumboreal (2012)
    American Geophysical Union
    Details
    Publication Date: 2022-05-25
    Description: 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 Global Biogeochemical Cycles 26 (2012): GB0E02, doi:10.1029/2012GB004299.
    Description: While much of the dissolved organic carbon (DOC) within rivers is destined for mineralization to CO2, a substantial fraction of riverine bicarbonate (HCO3−) flux represents a CO2 sink, as a result of weathering processes that sequester CO2 as HCO3−. We explored landscape-level controls on DOC and HCO3− flux in subcatchments of the boreal, with a specific focus on the effect of permafrost on riverine dissolved C flux. To do this, we undertook a multivariate analysis that partitioned the variance attributable to known, key regulators of dissolved C flux (runoff, lithology, and vegetation) prior to examining the effect of permafrost, using riverine biogeochemistry data from a suite of subcatchments drawn from the Mackenzie, Yukon, East, and West Siberian regions of the circumboreal. Across the diverse catchments that we study, controls on HCO3− flux were near-universal: runoff and an increased carbonate rock contribution to weathering (assessed as riverwater Ca:Na) increased HCO3− yields, while increasing permafrost extent was associated with decreases in HCO3−. In contrast, permafrost had contrasting and region-specific effects on DOC yield, even after the variation caused by other key drivers of its flux had been accounted for. We used ionic ratios and SO4 yields to calculate the potential range of CO2 sequestered via weathering across these boreal subcatchments, and show that decreasing permafrost extent is associated with increases in weathering-mediated CO2 fixation across broad spatial scales, an effect that could counterbalance some of the organic C mineralization that is predicted with declining permafrost.
    Description: Funding for this work was provided through NSF-OPP-0229302 and NSF-OPP-0732985. Additional support to S.E.T. was provided by an NSERC Postdoctoral Fellowship.
    Description: 2013-02-21
    Keywords: Arctic ; Bicarbonate ; Dissolved organic carbon ; Permafrost
    Repository Name: Woods Hole Open Access Server
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  • 54
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    An unloading foam model to constrain Etna’s 11–13 January 2011 lava fountaining episode (2011)
    American Geophysical Union
    Details
    Publication Date: 2021-06-09
    Description: The 11–13 January 2011 eruptive episode at Etna volcano occurred after several months of increasing ash emissions from the summit craters, and was heralded by increasing SO2 output, which peaked at ∼5000 megagrams/day several hours before the start of the eruptive activity. The eruptive episode began with a phase of Strombolian activity from a pit crater on the eastern flank of the SE‐Crater. Explosions became more intense with time and eventually became transitional between Strombolian and fountaining, before moving into a lava fountaining phase. Fountaining was accompanied by lava output from the lower rim of the pit crater. Emplacement of the resulting lava flow field, as well as associated lava fountain‐ and Strombolian‐phases, was tracked using a remote sensing network comprising both thermal and visible cameras. Thermal surveys completed once the eruptive episode had ended also allowed us to reconstruct the emplacement of the lava flow field. Using a high temporal resolution geostationary satellite data we were also able to construct a detailed record of the heat flux during the fountain‐fed flow phase and its subsequent cooling. The dense rock volume of erupted lava obtained from the satellite data was 1.2 × 106 m3; this was emplaced over a period of about 6 h to give a mean output rate of ∼55 m3 s−1. By comparison, geologic data allowed us to estimate dense rock volumes of ∼0.85 × 106 m3 for the pyroclastics erupted during the lava fountain phase, and 0.84–1.7 × 106 m3 for lavas erupted during the effusive phase, resulting in a total erupted dense rock volume of 1.7–2.5 × 106 m3 and a mean output rate of 78–117 m3 s−1. The sequence of events and quantitative results presented here shed light on the shallow feeding system of the volcano.
    Description: Published
    Description: B11207
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: JCR Journal
    Description: partially_open
    Keywords: Etna ; lava fountains ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 55
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    Characterization of GPS time series at the Neapolitan volcanic area by statistical analysis (2011)
    American Geophysical Union
    Details
    Publication Date: 2012-02-03
    Description: The GPS time series recorded at the Neapolitan volcanic area reveals a very peculiar behavior. When a clear deformation is observed, the amplitude distribution evolves from a super‐Gaussian to a broader distribution. This behavior can be characterized by evaluating the kurtosis. Spurious periodic components were evidenced by independent component analysis and then removed by filtering the original signal. The time series for all stations was modeled with a fifth‐order polynomial fit, which represents the deformation history at that place. Indeed, when this polynomial is subtracted from the time series, the distributions again become super‐Gaussian. A simulation of the deformation time evolution was performed by superposing a Laplacian noise and a synthetic deformation history. The kurtosis of the obtained signals decreases as the superposition increases, enlightening the insurgence of the deformation. The presented approach represents a contribution aimed at adding further information to the studies about the deformation at the Neapolitan volcanic area by revealing geologically relevant data.
    Description: Published
    Description: B10416
    Description: 1.3. TTC - Sorveglianza geodetica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: GPS time series ; Neapolitan volcanic ; statistical analysis ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.01. Computational geophysics::05.01.04. Statistical analysis
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  • 56
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    Source Mechanism of Long Period events recorded by a high density seismic network during the 2008 eruption on Mt Etna (2011)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: 129 Long Period (LP) events, divided in two families were recorded by 50 stations deployed on Mount Etna within an eruptive context in the second half of June 2008. In order to understand the mechanisms of these events, we perform moment tensor inversion. Numerical tests show that unconstrained inversion leads to reliable moment tensor solutions because of the close proximity of numerous stations to the source positions. However, single forces cannot be accurately determined as they are very sensitive to uncertainities in the velocity model. These tests emphasize the importance of using stations located as close as possible to the source in the inversion of LP events. Inversion of LP signals is initially unconstrained, in order to estimate the most likely mechanism. Constrained inversions then allow us to accurately determine the structural orientations of the mechanisms. Inversions for both families show mechanisms with strong volumetric components. These events are generated by cracks striking SW-NE for both families and dipping 70± SE (fam. 1) and 50± NW (fam. 2). The geometries of the cracks are different from the structures obtained by the location of these events. The orientation of the cracks is consistent with the local tectonic context on Mount Etna. The LP events seem to be a response to the lava fountain occuring on the 10th of May, 2008.
    Description: In press
    Description: (38)
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: 3.1. Fisica dei terremoti
    Description: JCR Journal
    Description: open
    Keywords: Long-Period events ; earthquake source mechanism ; Etna Volcano ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics ; 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)
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  • 57
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    Improving the seismic monitoring of North-eastern Italy: the state of the art of the North-eastern Italy (NI) Seismic Network run by OGS (2011)
    EGU
    Details
    Publication Date: 2017-04-04
    Description: The Centro di Ricerche Sismologiche (CRS, Seismological Research Center) of the Istituto Nazionale di Oceanografia e di Geofisica Sperimentale (OGS, Italian National Institute for Oceanography and Experimental Geophysics) in Udine (Italy) after the strong earthquake of magnitude Mw=6.4 occurred in 1976 in the Italian Friuli-Venezia Giulia region, started to operate the North-eastern Italy (NI) Seismic Network: it currently consists of 12 very sensitive broad band and 21 simpler short period seismic stations, all telemetered to and acquired in real time at the OGS-CRS data center in Udine. Real time data exchange agreements in place with other Italian, Slovenian, Austrian and Swiss seismological institutes lead to a total number of 93 seismic stations acquired in real time, which makes the OGS the reference institute for seismic monitoring of North-eastern Italy. Since 2002 OGS-CRS is using the Antelope software suite on a SUN SPARC cluster as the main tool for collecting, analyzing, archiving and exchanging seismic data, initially in the framework of the EU Interreg IIIA project “Trans-national seismological networks in the South-Eastern Alps”. SeisComP is also used as a real time data exchange server tool. In order to improve the seismological monitoring of the North-eastern Italy area, at OGS-CRS we tuned existing programs and created ad hoc ones like: a customized web server named PickServer to manually relocate earthquakes, a script for automatic moment tensor determination, scripts for web publishing of earthquake parametric data, waveforms, state of health parameters and shaking maps, noise characterization by means of automatic spectra analysis, and last but not least scripts for email/SMS/fax alerting. A new OGS-CRS real time seismological website (http://rts.crs.inogs.it/) has also been operative since more than one year in the framework of the Italian DPC-INGV S3 Project: the website shows classic earthquake locations parametric data plus shakemap and moment tensor information; recently also daily PSD quality check of seismic stations plots have been added. At OGS-CRS we also spent a considerable amount of efforts in improving the long-period performances of broadband seismic stations, either by carrying out full re-installations and/or applying thermal insulations to the seismometers: the example of the new PRED broad band seismic station installation in the cave tunnel of Cave del Predil using a Quanterra Q330HR high resolution digitizer and a Sterckeisen STS-2 broadband seismometer will be illustrated. Efforts have been put also in strengthening the reliability of data links, exploring the use of redundant satellite/radio/GPRS links.
    Description: Published
    Description: Vienna (Austria)
    Description: 1.1. TTC - Monitoraggio sismico del territorio nazionale
    Description: open
    Keywords: seismic monitoring ; Northeastern Italy ; real time ; OGS ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 58
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    The initial phases of the 2008–2009 Mount Etna eruption: A multidisciplinary approach for hazard assessment (2011)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: Between 2007 and early 2008, the Istituto Nazionale di Geofisica e Vulcanologia (INGV) monitoring networks on Etna volcano recorded a recharging phase that climaxed with a new effusive eruption on 13 May 2008 and lasted about 14 months. A dike‐forming intrusion was accompanied by a violent seismic swarm, with more than 230 events recorded in the first 6 h, the largest being ML = 3.9. In the meanwhile, marked ground deformation was recorded by the permanent tilt and GPS networks, and sudden changes in the summit area were detected by five continuously recording magnetic stations. Poor weather conditions did not allow direct observation of the eruptive events, but important information was provided by infrared satellite images that detected the start of lava fountains from the eruptive fissure, feeding a lava flow. This flow spread within the Valle del Bove depression, covering 6.4 km on the southeastern flank of the volcano in a few hours. The seismicity and deformation pattern indicated that the dike‐forming intrusion was propagating northward. It produced a dry fracture field, which generated concern for the possibility that the eruptive fissures could expand downslope toward populated areas. Monitoring and modeling of the multidisciplinary data, together with the simulations of ash dispersal and lava flows, allowed us both to infer the eruptive mechanisms and to provide correct interpretation of the ongoing phenomena, furnishing useful information for civil defense purposes. We describe how this approach of feedback between monitoring and research provides critical support to risk evaluation.
    Description: We wish to thank all our colleagues from INGV Sezione di Catania for data collection, for the maintenance of the monitoring networks during the whole eruption, and for the many discussions about the interpretation of the eruptive events; the Etna Guides, the Funivia dell’Etna, and especially Alfio Mazzaglia and Nino Mazzaglia for the prompt information pertaining any news about the summit eruptive activity at Mount Etna; the Italian Civil Defense (DPC) for the close and efficient collaboration built up during the last height years of activity at Etna and other Sicilian volcanoes. We obtained MODIS data from NASA and SEVIRI data from EUMETSAT. We are indebted to Paul Davis for his B03203 BONACCORSO ET AL.: ETNA MULTIDISCIPLINARY HAZARD ASSESSMENT B03203 17 of 19 positive and encouraging comments. We thank the Associate Editor Michael P. Ryan, who helped greatly in improving the form of the manuscript. This study was undertaken with partial financial support from the INGV‐DPC 2007–2009 Agreement. Scientific papers funded by DPC do not represent its official opinion and politics. We thank Stephen Conway for revising the English language of this manuscript.
    Description: Published
    Description: B03203
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: JCR Journal
    Description: reserved
    Keywords: Etna ; effusive eruption ; hazard evaluation ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 59
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    Tsunami early warning using earthquake rupture duration and P-wave dominant-period: the importance of length and depth of faulting (2011)
    Wiley
    Details
    Publication Date: 2017-04-03
    Description: After an earthquake, rapid, real-time assessment of hazards such as ground shaking and tsunami potential is important for early warning and emergency response. Tsunami potential depends on sea floor displacement, which is related to the length, L, width, W, mean slip, D, and depth, z, of earthquake rupture. Currently, the primary discriminant for tsunami potential is the centroid-moment tensor magnitude, MwCMT, representing the seismic potency LWD, and estimated through an indirect, inversion procedure. The obtained MwCMT and the implied LWD value vary with the depth of faulting, assumed earth model and other factors, and is only available 30 min or more after an earthquake. The use of more direct procedures for hazard assessment, when available, could avoid these problems and aid in effective early warning. Here we present a direct procedure for rapid assessment of earthquake tsunami potential using two, simple measures on P-wave seismograms – the dominant period on the velocity records, Td, and the likelihood that the high-frequency, apparent rupture-duration, T0, exceeds 50-55 sec. T0 can be related to the critical parameters L and z, while Td may be related to W, D or z. For a set of recent, large earthquakes, we show that the period-duration product TdT0 gives more information on tsunami impact and size than MwCMT and other currently used discriminants. All discriminants have difficulty in assessing the tsunami potential for oceanic strike-slip and back-arc or upper-plate, intraplate earthquake types. Our analysis and results suggest that tsunami potential is not directly related to the potency LWD from the “seismic” faulting model, as is assumed with the use of the MwCMT discriminant. Instead, knowledge of rupture length, L, and depth, z, alone can constrain well the tsunami potential of an earthquake, with explicit determination of fault width, W, and slip, D, being of secondary importance. With available real-time seismogram data, rapid calculation of the direct, period- duration discriminant can be completed within 6-10 min after an earthquake occurs and thus can aid in effective and reliable tsunami early warning.
    Description: In press
    Description: 1.1. TTC - Monitoraggio sismico del territorio nazionale
    Description: JCR Journal
    Description: open
    Keywords: Earthquake dynamics ; Earthquake source observations ; Seismic monitoring ; Body waves ; Early warning ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
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  • 60
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    Evolution of an active lava flow field using a multitemporal LIDAR acquisition (2010)
    American Geophysical Union
    Details
    Publication Date: 2012-02-03
    Description: Application of light detection and ranging (LIDAR) technology in volcanology has 7 developed rapidly over the past few years, being extremely useful for the generation 8 of high‐spatial‐resolution digital elevation models and for mapping eruption products. 9 However, LIDAR can also be used to yield detailed information about the dynamics of 10 lava movement, emplacement processes occuring across an active lava flow field, and the 11 volumes involved. Here we present the results of a multitemporal airborne LIDAR survey 12 flown to acquire data for an active flow field separated by time intervals ranging from 13 15 min to 25 h. Overflights were carried out over 2 d during the 2006 eruption of Mt. Etna, 14 Italy, coincident with lava emission from three ephemeral vent zones to feed lava flow in 15 six channels. In total 53 LIDAR images were collected, allowing us to track the volumetric 16 evolution of the entire flow field with temporal resolutions as low as ∼15 min and at a 17 spatial resolution of 〈1 m. This, together with accurate correction for systematic errors, 18 finely tuned DEM‐to‐DEM coregistration and an accurate residual error assessment, 19 permitted the quantification of the volumetric changes occuring across the flow field. We 20 record a characteristic flow emplacement mode, whereby flow front advance and channel 21 construction is fed by a series of volume pulses from the master vent. Volume pulses 22 have a characteristic morphology represented by a wave that moves down the channel 23 modifying existing channel‐levee constructs across the proximal‐medial zone and building 24 new ones in the distal zone. Our high‐resolution multitemporal LIDAR‐derived DEMs 25 allow calculation of the time‐averaged discharge rates associated with such a pulsed flow 26 emplacement regime, with errors under 1% for daily averaged values.
    Description: This work was partially funded by the Italian 930 Dipartimento della Protezione Civile in the frame of the 2007–2009 Agree- 931 ment with Istituto Nazionale di Geofisica e Vulcanologia–INGV. A.F. 932 benefited from the MIUR‐FIRB project “Piattaforma di ricerca multi‐disci- 933 plinare su terremoti e vulcani (AIRPLANE)” n. RBPR05B2ZJ. S.T. 934 benefited from the project FIRB “Sviluppo di nuove tecnologie per la prote- 935 zione e difesa del territorio dai rischi naturali (FUMO)” funded by the Italian 936 Ministero dell’Istruzione, dell’Università e della Ricerca.
    Description: Published
    Description: B11203
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 1.10. TTC - Telerilevamento
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: LIDAR ; lava flow ; Etna ; 04. Solid Earth::04.04. Geology::04.04.99. 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 ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
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  • 61
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    A completeness analysis of the national seismic network of Italy (2010)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: Accepted for publication in Journal of Geophysical Research. Copyright (2009) American Geophysical Union. Further reproduction or electronic distribution is not permitted.
    Description: We present the first detailed study of earthquake detection capabilities of the Italian National Seismic Network and of the completeness threshold of its earthquake catalog. The network in its present form started operating on 16 April 2005 and is a significant improvement over the previous networks. For our analysis, we employed the PMC method as introduced by Schorlemmer and Woessner (2008). This method does not estimate completeness from earthquakes samples as traditional methods, mostly based on the linearity of earthquake-size distributions. It derives detection capabilities for each station of the network and synthesizes them into maps of detection probabilities for earthquakes of a given magnitude. Thus, this method avoids the many assumptions about earthquake distributions that traditional methods make. The results show that the Italian National Seismic Network is complete at $M=2.9$ for the entire territory excluding the islands of Sardinia, Pantelleria, and Lampedusa. At the $M=2.5$ level, which is the reporting threshold level of the Italian Civil Protection, the network may miss events in southern parts of Apulia and the western part of Sicily. The stations are connected through many different telemetry links to the operational datacenter in Rome. Scenario computations show that no significant drop in completeness occurs if one of the three major links fail, indicating a well-balanced network setup.
    Description: In press
    Description: 1.1. TTC - Monitoraggio sismico del territorio nazionale
    Description: JCR Journal
    Description: open
    Keywords: Italian seismicity ; earthquake detection capability ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
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  • 62
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    Topographic control on lava flow paths at Mount Etna, Italy: Implications for hazard assessment (2010)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: 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.
    Description: Published
    Description: F01019
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: reserved
    Keywords: 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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  • 63
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    Predicting the impact of lava flows at Mount Etna, Italy (2010)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: Forecasting the time, nature, and impact of future eruptions is difficult at volcanoes such as Mount Etna, in Italy, where eruptions occur from the summit and on the flanks, affecting areas distant from each other. Nonetheless, the identification and quantification of areas at risk from new eruptions are fundamental for mitigating potential human casualties and material damage. Here, we present new results from the application of a methodology to define flexible high‐resolution lava invasion susceptibility maps based on a reliable computational model for simulating lava flows at Etna and on a validation procedure for assessing the correctness of susceptibility mapping in the study area. Furthermore, specific scenarios can be extracted at any time from the simulation database, for land use and civil defense planning in the long term, to quantify, in real time, the impact of an imminent eruption, and to assess the efficiency of protective measures.
    Description: This work was sponsored by the Italian Ministry for Education, University and Research, FIRB project RBAU01RMZ4 “Lava flow simulations by Cellular Automata,” and by the National Civil Defense Department and INGV (National Institute of Geophysics and Volcanology), project V3_6/09 “V3_6 – Etna.”
    Description: Published
    Description: B04203
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: 3.6. Fisica del vulcanismo
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: 4.4. Scenari e mitigazione del rischio ambientale
    Description: JCR Journal
    Description: reserved
    Keywords: lava flows ; volcanic hazard ; 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::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.01. Computational geophysics::05.01.02. Cellular automata, fuzzy logic, genetic alghoritms, neural networks ; 05. General::05.01. Computational geophysics::05.01.05. Algorithms and implementation ; 05. General::05.02. Data dissemination::05.02.99. General or miscellaneous ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions ; 05. General::05.08. Risk::05.08.99. General or miscellaneous ; 05. General::05.09. Miscellaneous::05.09.99. General or miscellaneous
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  • 64
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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
    Publication Date: 2012-02-03
    Description: An edited version of this paper was published by AGU. Copyright (2010) American Geophysical Union
    Description: 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).
    Description: Published
    Description: Q09008
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: 1.3. TTC - Sorveglianza geodetica delle aree vulcaniche attive
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: 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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    Response of Mount Etna to dynamic stresses from distant earthquakes (2010)
    American Geophysical Union
    Details
    Publication Date: 2012-02-03
    Description: Influences of distant earthquakes on volcanic systems by dynamic stress transfer are well documented. We analyzed seismic signals and volcanic activity at Mount Etna during two periods, January 2006 and May 2008, that clearly showed variations coincident with distant earthquakes. In the first period, characterized by mild volcano activity, the effect of the dynamic stress transfer, caused by an earthquake in Greece (M = 6.8), was twofold: (1) banded tremor activity changed its features and almost disappeared; (2) a swarm of volcano‐tectonic (VT) earthquakes took place. The changes of the banded tremor were likely due to variations in rock permeability, caused by fluid flows driven by dynamic strain. The VT earthquake swarm probably developed as a secondary process, promoted by the dynamically triggered activation of magmatic fluids. The second period, May 2008, showed an intense explosive activity. During this interval, the dynamic stress transfer, associated with the arrival of the seismic waves of the Sichuan earthquake (M = 7.9), affected the character of the seismo‐volcanic signals and on the following day triggered an eruption. In particular, we observed changes in volcanic tremor and increases of both occurrence rate and energy of long period events. In this case, we suggest that dynamic stress transfer caused nucleation of new bubbles in volatile‐rich magma bodies with consequent buildup of pressure, highlighted by the increase of long period activity, followed by the occurrence of an eruption. We conclude that stresses from distant earthquakes are capable of modifying the state of the volcano.
    Description: Published
    Description: B12304
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Mt. Etna volcano ; dynamic stress transfer ; triggered eruption ; triggered seismicity ; volcano seismology ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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    Anatomy of an unstable volcano from InSAR: Multiple processes affecting flank instability at Mt. Etna, 1994–2008 (2010)
    American Geophysical Union
    Details
    Publication Date: 2012-02-03
    Description: An edited version of this paper was published by AGU. Copyright (2010) American Geophysical Union.
    Description: Volcano deformation may occur under different conditions. To understand how a volcano deforms, as well as relations with magmatic activity, we studied Mt. Etna in detail using interferometric synthetic aperture radar (InSAR) data from 1994 to 2008. From 1994 to 2000, the volcano inflated with a linear behavior. The inflation was accompanied by eastward and westward slip on the eastern and western flanks, respectively. The portions proximal to the summit showed higher inflation rates, whereas the distal portions showed several sectors bounded by faults, in some cases behaving as rigid blocks. From 2000 to 2003, the deformation became nonlinear, especially on the proximal eastern and western flanks, showing marked eastward and westward displacements, respectively. This behavior resulted from the deformation induced by the emplacement of feeder dikes during the 2001 and 2002–2003 eruptions. From 2003 to 2008, the deformation approached linearity again, even though the overall pattern continued to be influenced by the emplacement of the dikes from 2001 to 2002. The eastward velocity on the eastern flank showed a marked asymmetry between the faster sectors to the north and those (largely inactive) to the south. In addition, from 1994 to 2008 part of the volcano base (south, west, and north lower slopes) experienced a consistent trend of uplift on the order of ∼0.5 cm/yr. This study reveals that the flanks of Etna have undergone a complex instability resulting from three main processes. In the long term (103–104 years), the load of the volcano is responsible for the development of a peripheral bulge. In the intermediate term (≤101 years, observed from 1994 to 2000), inflation due to the accumulation of magma induces a moderate and linear uplift and outward slip of the flanks. In the short term (≤1 year, observed from 2001 to 2002), the emplacement of feeder dikes along the NE and south rifts results in a nonlinear, focused, and asymmetric deformation on the eastern and western flanks. Deformation due to flank instability is widespread at Mt. Etna, regardless of volcanic activity, and remains by far the predominant type of deformation on the volcano.
    Description: ESA provided the SAR data (Cat‐1 no. 4532 and GEO Supersite initiative). The DEM was obtained from the SRTM archive, while the ERS‐1/2 orbits are courtesy of the TU‐Delft, The Netherlands. This work was partially funded by INGV and the Italian DPC (DPCINGV project V4 “Flank”), the Italian DPC (under special agreement with IREA‐CNR), and the Italian Space Agency under contract “sistema rischio vulcanico (SRV).” The authors thank Francesco Casu, Paolo Berardino, and Riccardo Lanari for their support and Geoff Wadge and Michael Poland for their helpful and constructive review of the manuscript.
    Description: Published
    Description: B10405
    Description: 1.3. TTC - Sorveglianza geodetica delle aree vulcaniche attive
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 1.10. TTC - Telerilevamento
    Description: 3.2. Tettonica attiva
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: 3.6. Fisica del vulcanismo
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: reserved
    Keywords: Flank instability ; InSAR ; volcanoes ; Etna ; 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::04.04.06. 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::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions ; 05. General::05.04. Instrumentation and techniques of general interest::05.04.99. General or miscellaneous ; 05. General::05.08. Risk::05.08.99. General or miscellaneous
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    Long term variations at Campi Flegrei (Italy) volcanic system highlighted by the monitoring of hydrothermal activity (2010)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: Long duration time-series of the chemical composition of fumaroles and of soil CO2 flux reveal that important variations in the activity of the Solfatara fumarolic field, the most important hydrothermal site of Campi Flegrei, occurred in the 2000-2008 period. A continuous increase of the CO2 concentrations, and a general decrease of the CH4 concentrations are interpreted as the consequence of the increment of the relative amount of magmatic fluids, rich in CO2 and poor in CH4, hosted by the hydrothermal system. Contemporaneously, the H2O-CO2-He-N2 gas system shows remarkable compositional variations in the samples collected after July 2000 with respect to the previous ones, indicating the progressive arrival at the surface of a magmatic componentdifferent from that involved in the 1983-84 episode of volcanic unrest (1983-1984 bradyseism). The change starts in 2000 concurrently with the occurrence of relatively deep, long-period seismic events which were the indicator of the opening of an easy-ascent pathway for the transfer of magmatic fluids towards the shallower, brittle domain hosting the hydrothermal system. Since 2000, this magmatic gas source is active and causes ground deformations, seismicity as well as the expansion of the area affected by soil degassing of deeply derived CO2. Even though the activity will most probably be limited to the expulsion of large amounts of gases and thermal energy, as observed in other volcanoes and in the past activity of Campi Flegrei, the behavior of the system in the future is, at the moment, unpredictable.
    Description: In press
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: JCR Journal
    Description: open
    Keywords: Solfatara crater ; CO2 content ; hydrothermal system ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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    Signals from the Campi Flegrei hydrothermal system: Role of a ‘‘magmatic’’ source of fluids (2010)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: This is a parametric study that was carried out to investigate the signals generated by a hydrothermal system fed by a pulsating source of magmatic fluids. This study focuses on the effects that selected properties of the source have on the evolution of hydrothermal activity at Campi Flegrei, Italy. Numerical simulations are carried out to describe a multiphase and multicomponent hydrothermal system. Each simulation describes a short unrest phase, followed by a prolonged quiet period. During the unrest, specific properties of the fluid source (flow rate, fluid composition, source size, and unrest duration) are modified with respect to selected baseline values. The evolution of the system is tracked by looking at two parameters that can be monitored in active volcanic areas: the composition of fumarolic gases and gravity changes. The results describe the temporal evolution of these two observables and allow comparisons of the effects of different source properties. All of the simulated unrest events cause measurable changes in gas composition and gravity. For the geometry and system properties considered, these changes always last beyond the end of the unrest period, and can often persist for decades. Fluid flow rate is the source property that mostly affects the observable evolution. Gravity is more sensitive to source properties than gas composition, and it undergoes the largest and quickest changes. The results also highlight the major role that rock properties and initial conditions have in the evolution of these observable signals.
    Description: Department of Civil Protection
    Description: Published
    Description: B05201
    Description: 3.6. Fisica del vulcanismo
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: reserved
    Keywords: hydrothermal fluids ; modeling ; monitoring ; signals ; 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::04.08.08. Volcanic risk
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    New insights into banded tremor from the 2008–2009 Mount Etna eruption (2010)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: We investigated the banded tremor activity occurring at Mt. Etna volcano between August-October 2008 during the 2008-2009 eruption. The banded tremor occurred in episodes lasting 25-30 minutes with intervals in between the episodes of about 25 minutes. Seismic signal analyses showed that the banded tremor was characterised by spectral contents, wavefields and source locations that differed from the “ordinary” volcanic tremor. The infrasound recordings exhibited an intermittent infrasonic tremor alternating with the banded tremor episodes. Finally, nonlinear analyses suggested that banded tremor system can be considered chaotic, implying: i) sensitive dependence on initial conditions, suggesting not only that a banded tremor system requires particular conditions to generate, but also that slight variations of these conditions are able to greatly change the features of the banded tremor or even to stop it; ii) long-term unpredictability, that is, the impossibility to forecast the long-term evolution of the banded tremor. On the basis of all these results and analogies with geyser models, we suggest a model of banded tremor that invokes alternating recharge-discharge phases. Banded tremor is due to “perturbations” in shallow aquifers, such as fluid movement and bubble growth or collapse due to hydrothermal boiling, triggered by the heat and hot fluid transfer from the underlying magma bodies. This heat-fluid transfer also causes an increasing pressure in the aquifer leading to fluid-discharge. During this process the seismic radiation decreases and, if the fluid-discharge is well coupled with the atmosphere, acoustic signals are generated.
    Description: Published
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Banded tremor ; Mt. Etna volcano ; volcano seismology ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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    Modeling of unrest signals in heterogeneous hydrothermal systems (2010)
    American Geophysical Union
    Details
    Publication Date: 2019-10-10
    Description: An edited version of this paper was published by AGU. Copyright (2010) American Geophysical Union.
    Description: Monitoring of quiescent volcanoes, such as Campi Flegrei (Italy), involves the measurement of geochemical and geophysical parameters that are expected to change as eruptive conditions approach. Some of these changes are associated with the hydrothermal activity that is driven by the release of heat and magmatic fluids. This work focuses on the properties of the porous medium and on their effects on the signals generated by the circulating fluids. The TOUGH2 porous media flow model is applied to simulate a shallow hydrothermal system fed by a source of magmatic fluids. The simulated activity of the source, with periods of increased fluid discharge, generates changes in gas composition, gravity, and ground deformation. The same boundary conditions and source activity were applied to simulate the evolution of homogeneous and heterogeneous systems, characterized by different rock properties. Phase distribution, fluid composition, and the related signals depend on the nature and properties of the rock sequence through which the fluids propagate. Results show that the distribution of porosity and permeability affects all the observable parameters, controlling the timing and the amplitude of their changes through space and time. Preferential pathways for fluid ascent favor a faster evolution, with larger changes near permeable channels. Slower changes over wider areas characterize less permeable systems. These results imply that monitoring signals do not simply reflect the evolution of the magmatic system: intervening rocks leave a marked signature that should be taken into account when monitoring data are used to infer system conditions at depth.
    Description: This work was carried out within the research project V1-UNREST, founded by the Italian Civil Protection Department
    Description: Published
    Description: B09213
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: open
    Keywords: hydrothermal circulation ; observable ; volcanic unrest ; permeability ; 03. Hydrosphere::03.04. Chemical and biological::03.04.06. Hydrothermal systems ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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    A completeness analysis of the national seismic network of Italy (2010)
    American Geophysical Union
    Details
    Publication Date: 2020-02-24
    Description: An edited version of this paper was published by AGU. Copyright (2010) American Geophysical Union.
    Description: We present the first detailed study of earthquake detection capabilities of the Italian National Seismic Network and of the completeness threshold of its earthquake catalog. The network in its present form started operating on 16 April 2005 and is a significant improvement over the previous networks. For our analysis, we employed the PMC method as introduced by Schorlemmer and Woessner (2008). This method does not estimate completeness from earthquakes samples as traditional methods, mostly based on the linearity of earthquake-size distributions. It derives detection capabilities for each station of the network and synthesizes them into maps of detection probabilities for earthquakes of a given magnitude. Thus, this method avoids the many assumptions about earthquake distributions that traditional methods make. The results show that the Italian National Seismic Network is complete at M=2.9 for the entire territory excluding the islands of Sardinia, Pantelleria, and Lampedusa. At the M=2.5 level, which is the reporting threshold level of the Italian Civil Protection, the network may miss events in southern parts of Apulia and the western part of Sicily. The stations are connected through many different telemetry links to the operational datacenter in Rome. Scenario computations show that no significant drop in completeness occurs if one of the three major links fail, indicating a well-balanced network setup.
    Description: Published
    Description: B04308
    Description: 5.2. TTC - Banche dati di sismologia strumentale
    Description: JCR Journal
    Description: open
    Keywords: Completeness Analysis ; Italian Seismicity ; Minimum Magnitude of Completeness ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
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    Short‐term and long‐term tremor migration patterns of the Cascadia 2004 tremor and slow slip episode using small aperture seismic arrays (2010)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: An edited version of this paper was published by AGU. Copyright (2010) American Geophysical Union.
    Description: Tectonic tremor has been recorded at many subduction zones, including the Nankai, Cascadia, Mexican, and Alaskan subduction zones. This study, the first to use small aperture seismic arrays to track tremor, deployed three small aperture seismic arrays along the Cascadia subduction zone during a tremor and slow slip episode in July 2004. The tremor was active during virtually all (up to 99%) minutes of the analyzed tremor episode using 5 min sample windows. Individual wave phases were tracked across the arrays and used to derive slowness vectors. These were compared with slowness vectors computed from a standard layered Earth model to derive tremor locations. Locations were stable within a volume roughly 250 km2 in epicenter and 20 km in depth for hours to days before moving to a new volume. The migration between volumes was not smooth, and the movement of the sources within the volume followed no specific pattern. Overall migration speeds along the strike of the subduction zone were between 5 and 15 km/d; smaller scale migration speeds between volumes reached speeds up to 2 km/min. Uncertainties in the best locations were 5 km in epicenter and 10 km in depth. For this data set and processing methodology, tremor does not locate predominately on the primary subduction interface. Our favored model for the generation of tectonic tremor signals is that the tremor is triggered by stress and fluid pressure changes caused by slow slip and is composed, at least in part, of low‐frequency earthquakes broadly distributed in location
    Description: Published
    Description: B00A24
    Description: 3.2. Tettonica attiva
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: reserved
    Keywords: tremor migration ; Cascadia 2004 ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis ; 04. Solid Earth::04.07. Tectonophysics::04.07.04. Plate boundaries, motion, and tectonics
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    Lability of DOC transported by Alaskan rivers to the Arctic Ocean (2010)
    American Geophysical Union
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © American Geophysical Union, 2008. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 35 (2008): L03402, doi:10.1029/2007GL032837.
    Description: Arctic rivers transport huge quantities of dissolved organic carbon (DOC) to the Arctic Ocean. The prevailing paradigm is that DOC in arctic rivers is refractory and therefore of little significance for the biogeochemistry of the Arctic Ocean. We show that there is substantial seasonal variability in the lability of DOC transported by Alaskan rivers to the Arctic Ocean: little DOC is lost during incubations of samples collected during summer, but substantial losses (20–40%) occur during incubations of samples collected during the spring freshet when the majority of the annual DOC flux occurs. We speculate that restricting sampling to summer may have biased past studies. If so, then fluvial inputs of DOC to the Arctic Ocean may have a much larger influence on coastal ocean biogeochemistry than previously realized, and reconsideration of the role of terrigenous DOC on carbon, microbial, and food-web dynamics on the arctic shelf will be warranted.
    Description: This material is based on work supported by the National Science Foundation under grant numbers OPP-0436106, OPP- 0519840, and EAR-0403962, and is a contribution to the Study of Environmental Arctic Change (SEARCH).
    Keywords: DOC ; Arctic ; Rivers
    Repository Name: Woods Hole Open Access Server
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    Mixing across the Arctic Ocean : microstructure observations during the Beringia 2005 Expedition (2010)
    American Geophysical Union
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © American Geophysical Union, 2008. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 35 (2008): L08606, doi:10.1029/2008GL033532.
    Description: Turbulent-scale temperature and conductivity were measured during the pan-arctic Beringia 2005 Expedition. The rates of dissipation of thermal variance and diapycnal diffusivities are calculated along a section from Alaska to the North Pole, across deep flat basins (Canada and Makarov Basins) and steep ridges (Alpha-Mendeleev and Lomonosov Ridges). The mixing rates are observed to be small relative to lower latitudes but also remarkably non-uniform. Relatively elevated turbulence is found over deep topography, confirming the dominant role of bottom-generated internal waves. Measured patterns of mixing in the Arctic are also associated with other mechanisms, such as double-diffusive structures and deep overflows. A better knowledge of the distribution of mixing is essential to understand the dynamics of the changing Arctic environment.
    Description: This work was funded by the National Science Foundation through a Small Grant for Exploratory Research (ARC-0527874) and grant ARC-0612342 with additional support from the Doherty Foundation and internal WHOI Funds.
    Keywords: Turbulence ; Arctic ; Topography
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    Eddy transport of organic carbon and nutrients from the Chukchi Shelf : impact on the upper halocline of the western Arctic Ocean (2010)
    American Geophysical Union
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © American Geophysical Union, 2007. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 112 (2007): C05011, doi:10.1029/2006JC003899.
    Description: In September 2004 a detailed physical and chemical survey was conducted on an anticyclonic, cold-core eddy located seaward of the Chukchi Shelf in the western Arctic Ocean. The eddy had a diameter of ∼16 km and was centered at a depth of ∼160 m between the 1000 and 1500 m isobaths over the continental slope. The water in the core of the eddy (total volume of 25 km3) was of Pacific origin, and contained elevated concentrations of nutrients, organic carbon, and suspended particles. The feature, which likely formed from the boundary current along the edge of the Chukchi Shelf, provides a mechanism for transport of carbon, oxygen, and nutrients directly into the upper halocline of the Canada Basin. Nutrient concentrations in the eddy core were elevated compared to waters of similar density in the deep Canada Basin: silicate (+20 μmol L−1), nitrate (+5 μmol L−1), and phosphate (+0.4 μmol L−1). Organic carbon in the eddy core was also elevated: POC (+3.8 μmol L−1) and DOC (+11 μmol L−1). From these observations, the eddy contained 1.25 × 109 moles Si, 4.5 × 108 moles NO3 −, 5.5 × 107 moles PO3 −, 1.2 × 108 moles POC, and 1.9 × 109 moles DOC, all available for transport to the interior of the Canada Basin. This suggests that such eddies likely play a significant role in maintaining the nutrient maxima observed in the upper halocline. Assuming that shelf-to-basin eddy transport is the dominant renewal mechanism for waters of the upper halocline, remineralization of the excess organic carbon transported into the interior would consume 6.70 × 1010 moles of O2, or one half the total oxygen consumption anticipated arising from all export processes impacting the upper halocline.
    Description: This work was supported by the National Science Foundation, and office of Naval Research; DH OPP-0124900, NB OPP-0124868, DK OPP 0124872, RP N00014-02-1-0317.
    Keywords: Arctic ; Eddy ; Carbon ; Nutrients ; Shelf-basin exchange ; Chukchi Sea
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    Recent changes in nitrate and dissolved organic carbon export from the upper Kuparuk River, North Slope, Alaska (2010)
    American Geophysical Union
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © American Geophysical Union, 2007. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 112 (2007): G04S60, doi:10.1029/2006JG000371.
    Description: Export of nitrate and dissolved organic carbon (DOC) from the upper Kuparuk River between the late 1970s and early 2000s was evaluated using long-term ecological research (LTER) data in combination with solute flux and catchment hydrology models. The USGS Load Estimator (LOADEST) was used to calculate June–August export from 1978 forward. LOADEST was then coupled with a catchment-based land surface model (CLSM) to estimate total annual export from 1991 to 2001. Simulations using the LOADEST/CLSM combination indicate that annual nitrate export from the upper Kuparuk River increased by ~5 fold and annual DOC export decreased by about one half from 1991 to 2001. The decrease in DOC export was focused in May and was primarily attributed to a decrease in river discharge. In contrast, increased nitrate export was evident from May to September and was primarily attributed to increased nitrate concentrations. Increased nitrate concentrations are evident across a wide range of discharge conditions, indicating that higher values do not simply reflect lower discharge in recent years but a significant shift to higher concentration per unit discharge. Nitrate concentrations remained elevated after 2001. However, extraordinarily low discharge during June 2004 and June–August 2005 outweighed the influence of higher concentrations in determining export during these years. The mechanism responsible for the recent increase in nitrate concentrations is uncertain but may relate to changes in soils and vegetation associated with regional warming. While changes in nitrate and DOC export from arctic rivers reflect changes in terrestrial ecosystems, they also have significant implications for Arctic Ocean ecosystems.
    Description: This work was supported by the Arctic System Science Program of the National Science Foundation (OPP- 0436118) and by NSF funding for the Arctic LTER through a series of grants from 1987 to present.
    Keywords: Nitrate ; DOC ; Arctic ; Rivers ; Change
    Repository Name: Woods Hole Open Access Server
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  • 77
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    Role of tides in Arctic ocean/ice climate (2010)
    American Geophysical Union
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © American Geophysical Union, 2007. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 112 (2007): C04S06, doi:10.1029/2006JC003643.
    Description: A three-dimensional coupled ocean/ice model, intended for long-term Arctic climate studies, is extended to include tidal effects. From saved output of an Arctic tides model, we introduce parameterizations for (1) enhanced ocean mixing associated with tides and (2) the role of tides fracturing and mobilizing sea ice. Results show tides enhancing loss of heat from Atlantic waters. The impact of tides on sea ice is more subtle as thinning due to enhanced ocean heat flux competes with net ice growth during rapid openings and closings of tidal leads. Present model results are compared with an ensemble of nine models under the Arctic Ocean Model Intercomparison Project (AOMIP). Among results from AOMIP is a tendency for models to accumulate excessive Arctic Ocean heat throughout the intercomparison period 1950 to 2000 which is contrary to observations. Tidally induced ventilation of ocean heat reduces this discrepancy.
    Description: This research is supported by the National Science Foundation Office of Polar Programs under cooperative agreements OPP-0002239 and OPP-0327664 with the International Arctic Research Center, University of Alaska Fairbanks.
    Keywords: Tide ; Arctic ; Climate
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  • 78
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    Hydrothermal activity on the ultra-slow spreading southern Knipovich Ridge (2010)
    American Geophysical Union
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © American Geophysical Union, 2007. 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 8 (2007): Q08013, doi:10.1029/2007GC001652.
    Description: We report first evidence for hydrothermal activity from the southern Knipovich Ridge, an ultra-slow spreading ridge segment in the Norwegian-Greenland Sea. Evidence comes from optical backscatter anomalies collected during a systematic side-scan sonar survey of the ridge axis, augmented by the identification of biogeochemical tracers in the overlying water column that are diagnostic of hydrothermal plume discharge (Mn, CH4, ATP). Analysis of coregistered geologic and oceanographic data reveals that the signals we have identified are consistent with a single high-temperature hydrothermal source, located distant from any of the axial volcanic centers that define second-order segmentation along this oblique ridge system. Rather, our data indicate a hydrothermal source associated with highly tectonized seafloor that may be indicative of serpentinizing ultramafic outcrops. Consistent with this hypothesis, the hydrothermal plume signals we have detected exhibit a high methane to manganese ratio of 2–3:1. This is higher than that typical of volcanically hosted vent sites and provides further evidence that the source of the plume signals reported here is most probably a high-temperature hydrothermal field that experiences some ultramafic influence (compare to Rainbow and Logachev sites, Mid-Atlantic Ridge). While such sites have previously been invoked to be common on the SW Indian Ridge, this may be the first such site to be located along the Arctic ultra-slow spreading ridge system.
    Description: Connelly and German were funded by NERC grant NER/B/S/ 2000/00755, NERC Core Strategic Funding at NOC, and the ChEss project of the Census of Marine Life.
    Keywords: Hydrothermal ; Arctic ; Serpentinization ; Knipovich Ridge
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  • 79
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    Sediment and nutrient delivery from thermokarst features in the foothills of the North Slope, Alaska : potential impacts on headwater stream ecosystems (2010)
    American Geophysical Union
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © American Geophysical Union, 2008. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 113 (2008): G02026, doi:10.1029/2007JG000470.
    Description: Permafrost is a defining characteristic of the Arctic environment. However, climate warming is thawing permafrost in many areas leading to failures in soil structure called thermokarst. An extensive survey of a 600 km2 area in and around the Toolik Lake Natural Research Area (TLNRA) revealed at least 34 thermokarst features, two thirds of which were new since ∼1980 when a high resolution aerial survey of the area was done. Most of these thermokarst features were associated with headwater streams or lakes. We have measured significantly increased sediment and nutrient loading from thermokarst features to streams in two well-studied locations near the TLNRA. One small thermokarst gully that formed in 2003 on the Toolik River in a 0.9 km2 subcatchment delivered more sediment to the river than is normally delivered in 18 years from 132 km2 in the adjacent upper Kuparuk River basin (a long-term monitoring reference site). Ammonium, nitrate, and phosphate concentrations downstream from a thermokarst feature on Imnavait Creek increased significantly compared to upstream reference concentrations and the increased concentrations persisted over the period of sampling (1999–2005). The downstream concentrations were similar to those we have used in a long-term experimental manipulation of the Kuparuk River and that have significantly altered the structure and function of that river. A subsampling of other thermokarst features from the extensive regional survey showed that concentrations of ammonium, nitrate, and phosphate were always higher downstream of the thermokarst features. Our previous research has shown that even minor increases in nutrient loading stimulate primary and secondary production. However, increased sediment loading could interfere with benthic communities and change the responses to increased nutrient delivery. Although the terrestrial area impacted by thermokarsts is limited, the aquatic habitat altered by these failures can be extensive. If warming in the Arctic foothills accelerates thermokarst formation, there may be substantial and wide-spread impacts on arctic stream ecosystems that are currently poorly understood.
    Description: The results presented in this report are based upon work supported by the U.S. National Science Foundation under grants to the Arctic Hyporheic project (OPP- 0327440) and the Arctic Long-Term Ecological Research Program (DEB- 9810222).
    Keywords: Arctic ; Climate change ; Streams ; Ecosystem dynamics ; Sediment ; Thermokarst ; Water quality
    Repository Name: Woods Hole Open Access Server
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  • 80
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    Influences of the ocean surface mixed layer and thermohaline stratification on Arctic Sea ice in the central Canada Basin (2010)
    American Geophysical Union
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © American Geophysical Union, 2010. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 115 (2010): C10018, doi:10.1029/2009JC005660.
    Description: Variations in the Arctic central Canada Basin mixed layer properties are documented based on a subset of nearly 6500 temperature and salinity profiles acquired by Ice-Tethered Profilers during the period summer 2004 to summer 2009 and analyzed in conjunction with sea ice observations from ice mass balance buoys and atmosphere-ocean heat flux estimates. The July–August mean mixed layer depth based on the Ice-Tethered Profiler data averaged 16 m (an overestimate due to the Ice-Tethered Profiler sampling characteristics and present analysis procedures), while the average winter mixed layer depth was only 24 m, with individual observations rarely exceeding 40 m. Guidance interpreting the observations is provided by a 1-D ocean mixed layer model. The analysis focuses attention on the very strong density stratification at the base of the mixed layer in the Canada Basin that greatly impedes surface layer deepening and thus limits the flux of deep ocean heat to the surface that could influence sea ice growth/decay. The observations additionally suggest that efficient lateral mixed layer restratification processes are active in the Arctic, also impeding mixed layer deepening.
    Description: Support for the ITP program and this study was provided by the U. S. National Science Foundation and the Woods Hole Oceanographic Institution. Support for the IMB program came from the National Science Foundation and the National Oceanographic and Atmospheric Administration.
    Keywords: Mixed layer ; Arctic
    Repository Name: Woods Hole Open Access Server
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  • 81
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    Age characteristics of a shelf-break eddy in the western Arctic and implications for shelf-basin exchange (2010)
    American Geophysical Union
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © American Geophysical Union, 2008. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 113 (2008): C02018, doi:10.1029/2007JC004429.
    Description: Radioisotope evaluation of a cold-core, anticyclonic eddy surveyed in September 2004 on the Chukchi Sea continental slope was used to determine its age since formation over the shelf environment. Because the eddy can be shown to have been generated near the shelf break, initial conditions for several age-dependent tracers could be relatively well constrained. A combination of 228Ra/226Ra, excess 224Ra, and 228Th/228Ra suggested an age on the order of months. This age is consistent with the presence of elevated concentrations of nutrients, organic carbon, suspended particles, and shelf-derived neritic zooplankton within the eddy compared to ambient offshore water in the Canada Basin but comparable to values measured in the Chukchi shelf and shelf-break environment. Hence this feature, at the edge of the deep basin, was poised to deliver biogeochemically significant shelf material to the central Arctic Ocean.
    Description: This work was supported by National Science Foundation Polar Programs grants OPP-662690 and OPP-66040N to the University of Miami (DK), and Office of Naval Research grant N00014-02-1-0317 (RP).
    Keywords: Arctic ; Eddy ; Radium
    Repository Name: Woods Hole Open Access Server
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  • 82
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    The Arctic freshwater system : changes and impacts (2010)
    American Geophysical Union
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © American Geophysical Union, 2007. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 112 (2007): G04S54, doi:10.1029/2006JG000353.
    Description: Dramatic changes have been observed in the Arctic over the last century. Many of these involve the storage and cycling of fresh water. On land, precipitation and river discharge, lake abundance and size, glacier area and volume, soil moisture, and a variety of permafrost characteristics have changed. In the ocean, sea ice thickness and areal coverage have decreased and water mass circulation patterns have shifted, changing freshwater pathways and sea ice cover dynamics. Precipitation onto the ocean surface has also changed. Such changes are expected to continue, and perhaps accelerate, in the coming century, enhanced by complex feedbacks between the oceanic, atmospheric, and terrestrial freshwater systems. Change to the arctic freshwater system heralds changes for our global physical and ecological environment as well as human activities in the Arctic. In this paper we review observed changes in the arctic freshwater system over the last century in terrestrial, atmospheric, and oceanic systems.
    Description: The authors gratefully acknowledge the National Science Foundation (NSF) for funding this synthesis work. This paper is principally the work of authors funded under the NSF-funded Freshwater Integration (FWI) study.
    Keywords: Arctic ; Freshwater ; System ; Changes ; Impacts
    Repository Name: Woods Hole Open Access Server
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  • 83
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    Detachment depth revealed by rollover deformation: An integrated approach at Mount Etna (2010)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: 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.
    Description: This work was partially funded by INGV and the DPC‐INGV project “Flank”, and partially by the ASI (SRV project).
    Description: Published
    Description: L16304
    Description: 1.3. TTC - Sorveglianza geodetica delle aree vulcaniche attive
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 1.10. TTC - Telerilevamento
    Description: 3.2. Tettonica attiva
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: reserved
    Keywords: 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)
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  • 84
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    Freshwater content variability in the Arctic Ocean (2010)
    American Geophysical Union
    Details
    Publication Date: 2022-05-26
    Description: Author Posting. © American Geophysical Union, 2004. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 109 (2004): C03051, doi:10.1029/2003JC001940.
    Description: Arctic Ocean model simulations have revealed that the Arctic Ocean has a basin-wide oscillation with cyclonic and anticyclonic circulation anomalies (Arctic Ocean Oscillation (AOO)) that has a prominent decadal variability [Proshutinsky and Johnson, 1997]. This study explores how the simulated AOO affects the Arctic Ocean stratification and its relationship to the sea ice cover variations. The simulation uses the Princeton Ocean Model coupled to sea ice [Häkkinen and Mellor, 1992; Häkkinen, 1999]. The surface forcing is based on National Centers for Environmental Prediction/National Center for Atmospheric Research Reanalysis and its climatology, of which the latter is used to force the model spin-up phase. Our focus is to investigate the competition between ocean dynamics and ice formation/melt on the Arctic basin-wide freshwater balance. We find that changes in the Atlantic water inflow can explain almost all of the simulated freshwater anomalies in the main Arctic basin. The Atlantic water inflow anomalies are an essential part of AOO, which is the wind driven barotropic response to the Arctic Oscillation (AO). The baroclinic response to AO, such as Ekman pumping in the Beaufort Gyre, and ice melt/freeze anomalies in response to AO are less significant considering the whole Arctic freshwater balance.
    Description: We gratefully acknowledge the support from National Science Foundation under Grant No OPP-0230184 (AP) and from NASA Headquarters (SH).
    Keywords: Fresh water ; Arctic ; Variability
    Repository Name: Woods Hole Open Access Server
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  • 85
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    Secular sea level change in the Russian sector of the Arctic Ocean (2010)
    American Geophysical Union
    Details
    Publication Date: 2022-05-26
    Description: Author Posting. © American Geophysical Union, 2004. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 109 (2004): C03042, doi:10.1029/2003JC002007.
    Description: Sea level is a natural integral indicator of climate variability. It reflects changes in practically all dynamic and thermodynamic processes of terrestrial, oceanic, atmospheric, and cryospheric origin. The use of estimates of sea level rise as an indicator of climate change therefore incurs the difficulty that the inferred sea level change is the net result of many individual effects of environmental forcing. Since some of these effects may offset others, the cause of the sea level response to climate change remains somewhat uncertain. This paper is focused on an attempt to provide first-order answers to two questions, namely, what is the rate of sea level change in the Arctic Ocean, and furthermore, what is the role of each of the individual contributing factors to observed Arctic Ocean sea level change? In seeking answers to these questions we have discovered that during the period 1954–1989 the observed sea level over the Russian sector of the Arctic Ocean is rising at a rate of approximately 0.123 cm yr−1 and that after correction for the process of glacial isostatic adjustment this rate is approximately 0.185 cm yr−1. There are two major causes of this rise. The first is associated with the steric effect of ocean expansion. This effect is responsible for a contribution of approximately 0.064 cm yr−1 to the total rate of rise (35%). The second most important factor is related to the ongoing decrease of sea level atmospheric pressure over the Arctic Ocean, which contributes 0.056 cm yr−1, or approximately 30% of the net positive sea level trend. A third contribution to the sea level increase involves wind action and the increase of cyclonic winds over the Arctic Ocean, which leads to sea level rise at a rate of 0.018 cm yr−1 or approximately 10% of the total. The combined effect of the sea level rise due to an increase of river runoff and the sea level fall due to a negative trend in precipitation minus evaporation over the ocean is close to 0. For the Russian sector of the Arctic Ocean it therefore appears that approximately 25% of the trend of 0.185 cm yr−1, a contribution of 0.048 cm yr−1, may be due to the effect of increasing Arctic Ocean mass.
    Description: This material is based upon work supported by the National Science Foundation under grant 0136432.
    Keywords: Arctic ; Sea level rise ; Decadal variability ; Steric effects ; Inverted barometer effect ; Glacial isostatic adjustment
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  • 86
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    Deformation and eruptions at Mt. Etna (Italy): A lesson from 15 years of observations (2009)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: 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.
    Description: 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.
    Description: Published
    Description: L02309
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 1.10. TTC - Telerilevamento
    Description: 3.6. Fisica del vulcanismo
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: 4.5. Degassamento naturale
    Description: JCR Journal
    Description: partially_open
    Keywords: 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)
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  • 87
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    New inferences from spectral seismic energy measurement of a link between regional seismicity and volcanic activity at Mt. Etna, Italy (2009)
    EGU
    Details
    Publication Date: 2017-04-04
    Description: The existence of a relationship between regional seismicity and changes in volcanic activity has been the subject of several studies in the last years. Generally, activity in basaltic volcanoes such as Villarica (Chile) and Tungurahua (Ecuador) shows very little changes after the occurrence of regional earthquakes. In a few cases volcanic activity has changed before the occurrence of regional earthquakes, such as observed at Teide, Tenerife, in 2004 and 2005 (Tárraga et al., 2006). In this paper we explore the possible link between regional seismicity and changes in volcanic activity at Mt. Etna in 2006 and 2007. On 24 November, 2006 at 4:37:40 GMT an earthquake of magnitude 4.7 stroke the eastern coast of Sicily. The epicenter was localized 50 km SE of the south coast of the island, and at about 160 km from the summit craters of Mt. Etna. The SSEM (Spectral Seismic Energy Measurement) of the seismic signal at stations at 1 km and 6 km from the craters highlights that four hours before this earthquake the energy associated with volcanic tremor increased, reached a maximum, and finally became steady when the earthquake occurred. Conversely, neither before nor after the earthquake, the SSEM of stations located between 80 km and 120 km from the epicentre and outside the volcano edifice showed changes. On 5 September, 2007 at 21:24:13 GMT an earthquake of magnitude 3.2 and 7.9 km depth stroke the Lipari Island, at the north of Sicily. About 38 hours before the earthquake occurrence, there was an episode of lava fountain lasting 20 hours at Etna volcano. The SSEM of the seismic signal recorded during the lava fountain at a station located at 6 km from the craters highlights changes heralding this earthquake ten hours before its occurrence using the FFM method (e.g., Voight, 1988; Ortiz et al., 2003). A change in volcanic activity – with the onset of ash emission and Strombolian explosions – was observed a couple of hours before the occurrence of the regional earthquakes. It can be interpreted as the magmatic response to a change of the distribution of tectonic stress in the edifice before the earthquake. In the light of this hypothesis, we surmise that the magmatic system behaved similar to a dilatometer and promise news lines to forecasting the volcano activity.
    Description: EGU
    Description: Published
    Description: Vienna (Austria)
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: open
    Keywords: VOLCANIC ACTIVITY ; TREMOR ; EARTHQUAKE ; SSEM ; FAILURE FORECAST METHOD ; ETNA ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.06. Seismology::04.06.10. Instruments and techniques ; 05. General::05.01. Computational geophysics::05.01.01. Data processing ; 05. General::05.01. Computational geophysics::05.01.05. Algorithms and implementation
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 88
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    Identification of activity regimes by unsupervised pattern classification of volcanic tremor data. Case studies from Mt. Etna (2009)
    EGU
    Details
    Publication Date: 2017-04-04
    Description: The monitoring of the seismic background signal – commonly referred to as volcanic tremor - has become a key tool for volcanic surveillance, particularly when field surveys are unsafe and/or visual observations are hampered by bad weather conditions. Indeed, it could be demonstrated that changes in the state of activity of the volcano show up in the volcanic tremor signature, such as amplitude and frequency content. Hence, the analysis of the characteristics of volcanic tremor leads us to pass from a mere monoparametric vision of the data to a multivariate one, which can be tackled with modern concepts of multivariate statistics. For this aim we present a recently developed software package which combines various concepts of unsupervised classification, in particular cluster analysis and Kohonen maps. Unsupervised classification is based on a suitable definition of similarity between patterns rather than on a-priori knowledge of their class membership. It aims at the identification of heterogeneities within a multivariate data set, thus permitting to focalize critical periods where significant changes in signal characteristics are encountered. The application of the software is demonstrated on sample sets derived from Mt. Etna during eruptions in 2001, 2006 and 2007-8.
    Description: EGU
    Description: Published
    Description: Vienna (Austria)
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: open
    Keywords: PATTERN CLASSIFICATION ; TREMOR ; KOHONEN MAP ; CLUSTER ANALYSIS ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.01. Computational geophysics::05.01.01. Data processing ; 05. General::05.01. Computational geophysics::05.01.02. Cellular automata, fuzzy logic, genetic alghoritms, neural networks ; 05. General::05.01. Computational geophysics::05.01.05. Algorithms and implementation
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Abstract
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  • 89
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    The 2007 Stromboli eruption: event chronology and effusion rates using thermal infrared data (2009)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: Accepted for publication in Journal of Geophysical Research. Copyright (2009) American Geophysical Union. Further reproduction or electronic distribution is not permitted.
    Description: Using thermal infrared images recorded by a permanent thermal camera network maintained on Stromboli volcano (Italy), together with satellite and helicopter-based thermal image surveys, we have compiled a chronology of the events and processes occurring before and during Stromboli’s 2007 effusive eruption. These digital data also allow us to calculate the effusion rates and lava volumes erupted during the effusive episode. At the onset of the 2007 eruption, two parallel eruptive fissures developed within the North East crater, eventually breaching the NE flank of the summit cone and extending along the eastern margin of the Sciara del Fuoco. These fed a main effusive vent at 400 m a.s.l. to feed lava flows that extended to the sea. The effusive eruption was punctuated, on 15 March, by a paroxysm with features similar to the 5 April paroxysm that occurred during the 2002-03 effusive eruption. A total of between 3.2 x 106 m3 and 11 x 106 m3 of lava was erupted during the 2007 eruption over 34 days of effusive activity. More than half of this volume was emplaced during the first 5.5 days of the eruption. Although the 2007 effusive eruption had a comparable erupted volume to the previous (2002-03) effusive eruption, it had a shorter duration and thus a mean output rate (= total volume divided by eruption duration) that was one order of magnitude greater than the 2002-03 event (~2.4 m3 s-1 compared with 0.32±0.28 m3 s-1). In this paper, we discuss similarities and differences between these two effusive events, and interpret the processes occurring in 2007 in terms of the recent dynamics witnessed at Stromboli.
    Description: This paper was partially supported by a grant to S. Calvari (Project INGV-DPC Paroxysm V2/03, 2008-2010) funded by the Istituto Nazionale di Geofisica e Vulcanologia and by the Italian Civil Protection. Satellite-based effusion rate work by A. Steffke and A. Harris was supported by NASA grant NNG04GO64G "New Tools for Advanced Hot Spot Tracking".
    Description: In press
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: JCR Journal
    Description: open
    Keywords: Thermal mapping ; Stromboli ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 90
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    Retrieval of SO2 from thermal infrared satellite measurements: correction procedures for the effects of volcanic ash (2009)
    EGU
    Details
    Publication Date: 2017-04-04
    Description: The simultaneous presence of SO2 and ash in a volcanic plume can lead to a significant error in the SO2 column abundance retrieval when multispectral Thermal InfraRed (TIR) data are used. The ash particles within the plume with effective radii from 1 to 10μm reduce the Top Of Atmosphere (TOA) radiance in the entire TIR spectral range, including the channels used for SO2 retrieval. The net effect is a significant SO2 overestimation. In this work the interference of ash is discussed and two correction procedures for satellite SO2 volcanic plume retrieval in the TIR spectral range are developed to achieve an higher computational speed and a better accuracy. The ash correction can be applied when the sensor spectral range includes the 7.3 and/or 8.7μm SO2 absorption bands, and the split window bands centered around 11 and 12μm required for ash retrieval. This allows the possibility of simultaneous estimation of both volcanic SO2 and ash in the same data set. The proposed ash correction procedures have been applied to the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Spin Enhanced Visible and Infrared Imager (SEVIRI) measurements. Data collected during the 24 November 2006 Mt. Etna eruption have been used to illustrate the technique. The SO2 and ash estimation is carried out by using a best weighted least squares fit method and the Brightness Temperature Difference (BTD) procedures, respectively. The simulated TOA radiance Look-Up Table (LUT) needed for the SO2 column abundance and the ash retrievals have been computed using the MODTRAN 4 Radiative Transfer Model. The results show the importance of the ash correction on SO2 retrievals at 8.7μm, where the corrected SO2 column abundance values are less than 50% of the uncorrected values. The ash correction on SO2 retrieval at 7.3μm is much less important and only significant for low SO2 column abundances. Results also show that the simplified and faster correction procedure underestimates the ash correction compared with the more time consuming but more accurate correction procedure. Such underestimation is greater for instruments having better ground pixel resolution, i.e. greater for MODIS than for SEVIRI.
    Description: Published
    Description: 177–191
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 1.10. TTC - Telerilevamento
    Description: N/A or not JCR
    Description: open
    Keywords: volcanic ash retrieval ; volcanic so2 retrieval ; ash correction ; remote sensing ; MODIS ; SEVIRI ; Etna volcano ; 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::04.08.01. 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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  • 91
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    Investigation into magma degassing at Nyiragongo volcano, Democratic Republic of the Congo (2008)
    American Geophysical Union
    Details
    Publication Date: 2021-01-27
    Description: We report the first combined measurements of the composition and flux of gas emitted from Nyiragongo volcano by ground-based remote-sensing techniques. Ultraviolet spectroscopic measurements made in May/June 2005 and January 2006 indicate average SO2 emission rates of 38 kg s−1 and 23 kg s−1, respectively. Open-path Fourier transform infrared spectroscopic measurements obtained in May/June 2005, January 2006, and June 2007 indicate average molar proportions of 70, 24, 4.6, 0.87, 0.26, 0.11, and 0.0016% for H2O, CO2, SO2, CO, HCl, HF, and OCS, respectively. The composition of the plume was remarkably similar in 2005, 2006, and 2007, with little temporal variation in proportions of CO2, SO2, and CO, in particular, on the scale of seconds or days or even between the three field campaigns that span a period of 24 months. This stability persisted despite a wide range of degassing behaviors on the surface of the summit crater's lava lake (including discrete strombolian bursts and lava fountains) and variations in the SO2 emission rate. We explain these observations by a regime of steady state degassing in which bubbles nucleate and ascend in chemical equilibrium with the convecting magma. Short-term (seconds to minutes) temporal fluctuations in the SO2–HCl–HF composition were observed, and these are attributed to shallow degassing processes.
    Description: Published
    Description: Q02017
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Nyiragongo ; volcanic gas emissions ; FTIR ; DOAS ; remote sensing ; spectroscopy ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 92
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    Seismic Tomography Experiment at Italy's Stromboli Volcano (2008)
    American Geophysical Union
    Details
    Publication Date: 2021-07-14
    Description: From 25 November to 2 December 2006, the first active seismic tomography experiment at Stromboli volcano was carried out with the cooperation of four Italian research institutions. Researchers on board the R/V Urania of the Italian National Council of Research (CNR), which was equipped with a battery of four 210- cubic- inch generated injection air guns (GI guns), fired more than 1500 offshore shots along profiles and rings around the volcano.
    Description: DPC/INGV agreement 2004-2006
    Description: Published
    Description: 269-270
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.6. Fisica del vulcanismo
    Description: N/A or not JCR
    Description: reserved
    Keywords: Stromboli ; seismic tomography ; air-gun ; 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::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 93
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    Continuous monitoring of soil CO2 flux on Mt. Etna:The 2004–2005 eruption and the role of regional tectonics and volcano tectonics. (2008)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: The soil CO2 flux on Mt. Etna as recorded by the ETNAGAS network (an automatic system for measuring soil CO2 flux and meteorological parameters) started to increase strongly about 5 months prior to the onset of the 2004–2005 eruption and decreased a few months before the end of the eruption. Time delays in the occurrences of anomalies in soil CO2 flux at different sites in the geochemical network constrain the relationship between soil CO2 flux distributions and the tectonic framework of Etna volcano. The anomalies observed before the 2004–2005 eruption support the intrusion of new undegassed magma into the upper feeding system of the volcano (〈20 km below sea level). Magma subsequently rose slowly in the volcano conduits, thereby triggering the onset of the 2004–2005 eruption. The time delays in the occurrences of anomalies in combination with spectral analysis indicate the importance of tectonic and volcanotectonic structures in driving the ascent of deep gases within the crust. Moreover, greatest amplitude pulsations of the low-frequency components of the CO2 flux signals were correlated with the paroxystic activities of the 2004–2005 eruption. This study confirms that CO2 flux variation is a useful indicator for volcanic activity in the surveillance of the Mt. Etna and similar basaltic volcanoes.
    Description: Dipartimento Protezione Civile Ministero degli Interni
    Description: Published
    Description: B09206
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: JCR Journal
    Description: reserved
    Keywords: CO2 flux ; Continuous monitoring of soil CO2 flux ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 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::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
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  • 94
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    Gas Flux Rate and Migration of the Magma Column (2008)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: The 2002–2003 effusive eruption of Stromboli volcano represents an excellent opportunity to investigate the transition from effusive to explosive activity at an open-conduit basaltic system, when activity migrated from effusive vents, at the base of the craters, to summit explosions. The transition is investigated here through the analysis of very long period seismicity, delay times between infrasonic and thermal onsets of explosions, and SO2 flux recorded during a 1-year period. The synergy of the multiple geophysical observations points to a magma-driven migration of the magma column. Here the increased magma supply at the eruption onset lead to opening of effusive fissures, which draining the magma in the shallow conduit caused the decrease of the magma level. The decrease of the magma supply at the end of the effusion lead to sealing of effusive fissures, upraise of the magma level within the conduit, and reestablishment of explosive activity from the summit vents.
    Description: Unpublished
    Description: 11
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: 1.10. TTC - Telerilevamento
    Description: 3.6. Fisica del vulcanismo
    Description: reserved
    Keywords: Stromboli ; SO2 Flux ; Magma column ; Infrasound ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 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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  • 95
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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
    Publication Date: 2017-04-04
    Description: 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.
    Description: This work was supported financially by Istituto Nazionale di Geofisica e Vulcanologia and Dipartimento per la Protezione Civile, project INGV-DPC V4/02.
    Description: Published
    Description: Q04022
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: 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
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  • 96
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    Variation of H2O/CO2 and CO2/SO2 ratios of volcanic gases discharged by continuous degassing of Mount Etna volcano, Italy (2008)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: We applied the Multi-GAS technique to measure compositions of the volcanic plumes continuously discharged from summit craters of Voragine, Northeast and Bocca Nuova at Mount Etna, in an attempt to estimate compositions of the source volcanic gases. The estimated CO2/SO2 and H2O/CO2 ratios of the volcanic gases show a large variation ranging from 0.6 to 30 and from 1 to 18, respectively. This variability overlaps with the compositional range of dissolved volatiles in melt inclusions and their coexisting bubbles in a magma chamber and can be caused by the low-pressure degassing of a magma with variable bubble content ranging from 0.3 to 15 wt.%. The variable bubble content in the magma is likely a result of supply of deep-derived CO2-rich gas phase to the chamber and subsequent bubble-magma differentiation by bubble ascent in the magma chamber. In contrast, the variation of volcanic gas composition can also be caused by changes of degassing pressure (gas–magma separation pressure), ranging from 0 to 100 MPa, as a result of changes in the depth of the top of the convecting magma in volcanic conduits. Both mechanisms can cause similar compositional variations. However, the two mechanisms will result in contrasting correlations between the SO2 emission rates and the gas compositions that can be examined by parallel observations of the emission rates and compositions in the future.
    Description: Published
    Description: B09203
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: 4.5. Degassamento naturale
    Description: JCR Journal
    Description: reserved
    Keywords: Plume ; gas ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 97
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    Unmanned aerial vehicle measurements of volcanic carbon dioxide fluxes (2008)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: 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.
    Description: Published
    Description: L06303
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: 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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  • 98
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    2002–2003 Lava Flow Eruption of Stromboli: A Contribution to Understanding Lava Discharge Mechanisms Using Periodic Digital Photogrammetry Surveys (2008)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: Photogrammetric surveys were performed between 5 January and 26 July 2003 for monitoring the NW flank of the Sciara del Fuoco (SdF) during the eruption of Stromboli that started on 28 December 2002. The collected data were used both for controlling morphological changes after the major landslide that occurred on 30 December 2002 and lava flow field evolution until the end of the eruption (22 July 2003). The latter objective was achieved by a quantitative analysis which allowed to estimate the total lava volume (12.51 × 106 m3) emplaced on the SdF slope corresponding to an eruption rate of about 0.69 m3/s. Thanks to the availability of multitemporal data set, which made this event the first well-documented and regularly surveyed Stromboli eruption, the cumulative volume and effusion rate trends were derived. A model for interpreting the behavior of the 2002–2003 Stromboli effusive eruption is also proposed: being the vents located very close to the volcano summit, a typical summit (terminal) basaltic lava flow eruption was expected; on the contrary, the observed effusion rate trend showed an initial peak followed by an exponential decline typical of flank (lateral) eruptions of basaltic volcanoes. We recognized in this trend a transition from a terminal (open conduit system) to a lateral (pressurized dike system) lava discharge followed by a longer period in which the elastic strain energy from the subvolcanic reservoir controlled the effusion rate; this effect counterbalanced the lava cooling at dike tip that tends to close the eruptive fissure causing the eruption end.
    Description: Published
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: reserved
    Keywords: Stromboli ; Digital photogrammetry survey ; lava disharge mechanism ; morphological changes ; 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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  • 99
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    Link between major flank slip and 2002–2003 eruption at Mt. Etna (Italy) (2008)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: The 2002–2003 Etna eruption is studied through earthquake distributions and surface fracturing. In September 2002, earthquake-induced surface rupture (sinistral offset 0.48 m) occurred along the E-W striking Pernicana Fault (PF), on the NE flank. In late October, a flank eruption accompanied further ( 0.77 m) surface rupturing, reaching a total sinistral offset of 1.25 m; the deformation then propagated for 18 km eastwards to the coastline (sinistral offset 0.03 m) and southwards, along the NW-SE striking Timpe (dextral offset 0.04 m) and, later, Trecastagni faults (dextral offset 0.035 m). Seismicity (〈4 km bsl) on the E flank accompanied surface fracturing: fault plane solutions indicate an overall ESEWNWextension direction, consistent with ESE slip of the E flank also revealed by ground fractures. A three-stage model of flank slip is proposed: inception (September earthquake), climax (accelerated slip and eruption) and propagation (E and S migration of the deformation).
    Description: Published
    Description: 2286
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.2. Tettonica attiva
    Description: 3.5. Geologia e storia dei sistemi vulcanici
    Description: 3.6. Fisica del vulcanismo
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: reserved
    Keywords: volcano seismology ; surface fracturing ; flank slip ; eruption ; Etna ; 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::04.04. Geology::04.04.99. General or miscellaneous ; 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::04.06.01. Earthquake faults: properties and evolution ; 04. Solid Earth::04.06. Seismology::04.06.02. Earthquake interactions and probability ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk ; 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::04.08.03. 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::04.08.08. Volcanic risk ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
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  • 100
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    Volcanomagnetic Evidence of the Magmatic Intrusion on 13th May 2008 (2008)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: During the onset of 2008 volcanic crisis at Mt Etna, the near-real time magnetic data provided a continuous updating of the volcano activity state on the northern flank. On the morning of 13th May 2008, significant local magnetic field changes marked the resumption of the eruptive activity characterized by the opening of a fracture field on the northern flank, and an eruptive fissure in the Valle del Bove. In agreement with the northward propagation of seismic events, magnetic signals at 5 stations in the summit area revealed a nearly NNW-SSE oriented magmatic intrusion, which started at about 9:00 GMT, propagated northward for about 2 km, and stopped at 14:00 GMT before reaching the North-East Rift. Magnetic variations, with amplitude ranging between 1.8 nT and -6.5 nT, are consistent with those calculated from piezomagnetic models, where stress-induced changes in rock magnetization are produced by the magmatic intrusion.
    Description: Published
    Description: L22301
    Description: 2.6. TTC - Laboratorio di gravimetria, magnetismo ed elettromagnetismo in aree attive
    Description: JCR Journal
    Description: partially_open
    Keywords: Mt Etna ; volcano monitoring ; piezomagnetic field ; magmatic intrusion ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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