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The evolving Code of Conduct at the National Institute of Geophysics and Volcanology of Italy: a participatory process to combine law compliance and geoethics principles
No full textThe contribution illustrates the participatory process behind and main features of an updated version of the Code of Conduct in place at the National Institute of Geophysics and Volcanology of Italy.PublishedVienna, Austria2TM. Divulgazione Scientific
Extensive oxidizing events recorded by peridotite mantle xenoliths from the Hyblean Plateau: Evidence from combined measurements of ferric iron in spinel with noble gases and fluid inclusions chemistry in olivine
No full textThe study of the oxidation state of lithospheric mantle-derived rocks allows modelling the deep cycle of volatiles
(e.g., C, H, O, N and S) in the Earth’s interior, which in turn plays a role in magma genesis, metasomatism and
volcanic degassing. At the oxygen fugacity (i.e., fO2) recorded by residual abyssal peridotites, volatile elements
like carbon are predicted to be in the immobile form of graphite. However, the compilation of the redox state of
worldwide-distributed continental xenoliths shows evidence of their oxidation and refertilization through time
by deeply formed subduction-related metasomatic fluids. The analyses of fluid inclusions in mantle-derived
minerals like olivine (or pyroxenes) represent a snapshot of the volatile circulation in depth, whose noble
gases signature (He, Ar, Ne) is used to identify their possible source. This study aims to reconstruct the origin of
mantle metasomatism underneath the Hyblean Plateau (Sicily, Italy) and its redox history through the investigation of spinel-peridotite nodules, combining fO2 estimates with noble gases and fluid inclusions chemistry from hand-picked olivine grains. We analyzed eight mantle xenoliths classified as spinel lherzolites and spinel harzburgites from the Valle Guffari (Hyblean Plateau, Sicily). The calculated logfO2 is higher than that of most cratonic xenoliths worldwide ranging between 0.28 and 1.27 log units above to the fayalite-magnetite-quartz (FMQ) reference buffer. Micro-Raman measurements on olivine grains with dendritic trails of (metasomatic) fluid inclusions reveal an assemblage made of Mg-Ca carbonates ± sulfide ± elemental sulfur ± CO2 in the most reduced sample, and Mg-Ca carbonates ± sulfates ± CO2 in the most oxidized sample, the latter associated with a silicate glass and (secondary) hydrous phases. Both assemblages are taken as evidence of the product of crystallization of deeply originated volatile-bearing silicate melts. Analyses of He, Ar, and Ne in olivine grains confirm the evidence of a mantle source reworked by metasomatic processes. Our data suggest that an initially residual Hyblean lithospheric mantle was affected by extensive oxidizing events at several depths caused by the interaction with slab-derived CO2-rich silicate metasomatic liquids.Published107337OSV2: Complessità dei processi vulcanici: approcci multidisciplinari e multiparametriciJCR Journa
Aso volcano, Japan: assessing the 100-year probability of a new caldera-forming eruption based on expert judgements with Bayes Net and Importance Sampling uncertainty analysis
No full textThe Aso-4 explosive eruption on Kyushu, Japan, 89,500 years ago was one of the biggest eruptions in the last one hundred millennia, with a magnitude of approximately M8. Modern society requires the likelihood of natural events with potentially disastrous consequences to be evaluated, even if probabilities of occurrence are diminishingly small. For some situations, it is not satisfactory to assert an event scenario probability is “negligible” or can be “ignored”. Judicial hearings or litigation may require risk levels to be quantified, in which case, statements of scientific confidence could be decisive. Internation- ally, e.g., for nuclear site safety evaluations, event likelihoods on order of 10–7/year are often considered for quantitative assessment. At such hazard levels, this might include evaluating the proposition that a particular volcano can deliver
a future super-eruption, a supposition that could be attached to Aso volcano. But, simplistically taking the average recurrence interval between past caldera-forming eruptions at a given volcano is an unreliable guide to the likelihood
of a future repeat: each past event represented a unique set of tectonic and magmatic conditions within a continually evolving volcanic system. Such processes are not temporally stationary nor statistically uniform. To evaluate the probability of a new M8 event at Aso, within the next 100 years, we performed a comprehensive stochastic probability uncertainty analysis using a model implemented with advanced computational Bayes Net (BN) software. Our eruption process model is informed by multiple strands of evidence from volcanology, petrology, geochemistry and geophysics, together with estimates of epistemic (knowledge) uncertainty, adduced from reviews of published data, modelling and from expert judgement elicitation. Several lines of evidence characterise the likely structure, magmatic composition and eruptive state of the present-day Aso volcano, which has had numerous smaller eruptions since Aso-4. To calculate the probability of another M8 eruption of Aso, we implemented probabilistic ‘Importance Sampling’ in our model. With this approach, we find the chance of an Aso-4 scale eruption (characterised by mean volume 500 km3 DRE and approximate 90% credible interval [210 .. 1200] km3 DRE) is less than 1–in–1 billion in the next 100 years (i.e., < 10–9 probability). Based on current vol- canological understanding and evidence, we believe this probability estimate is robust to within an order of magnitude.Published5OSV1: Verso la previsione dei fenomeni vulcanici pericolosiN/A or not JC
Three-dimensional magnetotelluric modeling of Vulcano Island (Eolie, Italy) and its implications for understanding recent volcanic unrest
No full textThis paper presents the results of an original short-period magnetotelluric survey performed on Vulcano Island (Italy). The obtained three-dimensional resistivity model details structures up to 2.5 km depth, hitherto unexplored. The La Fossa caldera area corresponds to a moderate resistive anomaly, which extends down to the resolved depth and likely represents a "conduit-like" structure along which magmatic fluids stall and ascend. Other resistive anomalies characterize volcanic edifices, craters, volcanic conduits, and/or eruptive fissures. In addition, the shallower hydrothermal system is detected as a conductive anomaly. Sharp resistivity contrasts generally characterize caldera faults. A main N‒S alignment characterizes the island sector, where considerable amounts of deep subsurface fluids accumulate and mix with the ascending magmas related to the most recent volcanic dynamics. The volcanological interpretation of such findings significantly contributes to understanding the geophysical and geochemical anomalies detected in the last year, which involved the Vulcano shallow hydrothermal system, highlighting the potential for possible hydrothermal/phreatic eruptive events.Published16458OSV1: Verso la previsione dei fenomeni vulcanici pericolosiJCR Journa
Antarctic permafrost degassing in Taylor Valley by extensive soil gas investigation
No full textOngoing studies conducted in northern polar regions reveal that permafrost stability plays a key role in the modern carbon cycle as it potentially stores considerable quantities of greenhouse gases. Rapid and recent warming of the Arctic permafrost is resulting in significant greenhouse gas emissions, both from physical and microbial processes. The potential impact of greenhouse gas release from the Antarctic region has not, to date, been investigated. In Antarctica, the McMurdo Dry Valleys comprise 10 % of the ice-free soil surface areas in Antarctica and like the northern polar regions are also warming albeit at a slower rate. The work presented herein examines a comprehensive sample suite of soil gas (e.g., CO2, CH4 and He) concentrations and CO2 flux measurements conducted in Taylor Valley during austral summer 2019/2020. Analytical results reveal the presence of significant concentrations of CO2, CH4 and He (up to 3.44 vol%, 18,447 ppmv and 6.49 ppmv, respectively) at the base of the active layer. When compared with the few previously obtained measurements, we observe increased CO2 flux rates (estimated CO2 emissions in the study area of 21.6 km2 ≈ 15 tons day-1). We suggest that the gas source is connected with the deep brines migrating from inland (potentially from beneath the Antarctic Ice Sheet) towards the coast beneath the permafrost layer. These data provide a baseline for future investigations aimed at monitoring the changing rate of greenhouse gas emissions from Antarctic permafrost, and the potential origin of gases, as the southern polar region warms.Published1613456A. Geochimica per l'ambiente e geologia medicaJCR Journa
Laboratory simulation of fault reactivation by fluid injection and implications for induced seismicity at the BedrettoLab, Swiss Alps
No full textFluid induced fault reactivation experiments will take place as part of the “Fault Activation and Earthquake Rupture” project (FEAR) at the BedrettoLab, an underground laboratory for geosciences and geo-energy excavated within the Rotondo massif (Swiss Alps). The aim of this publication is to characterize frictional properties and permeability of the main segment of the fault zone selected for limited fluid-induced fault reactivation experiments. Firstly, we characterized fault zone microstructures in the field and in thin sections. Secondly, we assessed fault gouge mineralogy by X-ray powder diffraction analysis, yielding a composition in agreement with similar fault gouges in the same area. Finally, we performed a detailed frictional and permeability characterization in laboratory, using BRAVA (Brittle Rock deformAtion Versatile Apparatus). We performed five frictional experiments, run at the actual in-situ conditions: four experiments for frictional properties characterization; and one further experiment where we stimulated the experimental fault by fluid pressurization applying a similar injection protocol designed for the in-situ hydraulic stimulation experiment. Additionally, we performed microstructural analysis on experimental samples to link frictional and permeability properties with fault fabric evolution. The integration of experimental results with field investigations suggests that the selected fault is potentially seismogenic and can be dynamically reactivated and controlled with hydraulic stimulation. This study highlights the importance of bridging the gap between laboratory and in-situ fault characterization, where experimental results become instrumental for the correct design of injection protocols such as those of FEAR project.Published229987OST3 Vicino alla fagliaJCR Journa
Catalog of major explosions and paroxysms at Stromboli volcano (Italy) from 1970 to 2023
No full textThe catalog consists of the dataset of the major explosions and paroxysms recorded at Stromboli from Jan. 1970 to Oct. 2023, as reconstructed through a detailed review of monitoring bulletins and reports, previous catalogs, and scientific literature of the last ca. 50 years. The catalog includes the calendar date, GMT time and phenomena descriptions for 89 explosive events, of which 4 were paroxysms, 51 were major explosions, and 34 were uncertain major explosions, i.e. explosions of unclear characterization that could have been major explosions or ordinary activity.
We detailed the event information content in five columns – (i) seismicity, (ii) sound/air shock, (iii) vents involved, (iv) ash plume/fallout, (v) ballistic projectiles. In addition, we indicated if there were any: (vi) field survey, (vii) pumices erupted, (viii) fires, (ix) map of the products, (x) photo/video of the event, (xi) hot avalanche, (xii) lava flow. The catalog also includes a list of the original literature sources that helped us in the complex characterization of the explosive events. We finally reported if there were people affected by the events, and any previous catalog that comprised them.
In our analysis (see also Bevilacqua et al., 2020b), we mostly relied on the detailed characterization of major explosions and paroxysms in Rosi et al. 2013 that provided quantitative constraints on total duration, fallout volume, mass discharge rate, ballistic size, ballistic range and column height of ordinary activity, major explosions, and paroxysms. In several cases, we had to carefully evaluate the original description of the phenomena, due to insufficient quantitative information in the scientific literature.
In particular, we considered the hazardous area affected by large ballistic projectiles as the main discriminant factor to distinguish between ordinary activity, major explosions and paroxysms. This area is limited to the Crater Terrace and upper Sciara del Fuoco in case of ordinary activity, to the summit area of the volcano and Sciara del Fuoco during major explosions, and can extend down to low elevations along large part of the island, and sometimes beyond the shoreline, during the paroxysms (Barberi et al., 1993). We also considered several other factors, including the height of the plume, the amount of ash and scoria fallout, the occurrence and strength of any associated shock wave. The occurrence of fires associated with the violent explosive activity was assumed as a good marker for a major explosion too (Rosi et al., 2013).
Whilst identifying the paroxysms was relatively straightforward, several possible major explosions were not clearly distinguishable from particularly violent episodes of ordinary Strombolian activity. Thus, our historical record includes the quantification of the main sources of uncertainty, i.e. the possibility of 34 major explosions of uncertain characterization because of insufficient information. We followed a conservative approach and we classified as “uncertain major explosions” all the explosive events for which we could not exclude they were major explosions. This particular case often occurs in the 1970s, 1980s and 1990s, before the installation of surveillance cameras, and, afterwards, when these cameras were not operating for bad weather conditions or temporary malfunctions.
In addition, the catalog includes 41 seismic sequences typically associated with higher-than-usual explosive activity but with a size significantly smaller than that of major explosions. These events may have produced a limited ballistic fallout just outside of the crater terrace, i.e. few tens of meters, or short lived effusive activity (e.g. intra-crateric), but they are not associated with the dangerous ballistic fallout of major explosions.
About these seismic sequences, we relied on the characterization in Falsaperla & Spampinato, 2003, that is a variable number of explosion quakes in rapid succession (i.e. from tens of seconds to a few minutes), associated with a notable increment in the amplitude of volcanic tremor. This definition relies on the availability of seismic registrations, and therefore a significant under-recording may affect the period before June, 1985, when seismic records started to be acquired continuously at Stromboli. Afterwards, short lapses in the available registrations possibly generated slight underrecording of the seismic sequences in the 1990s and 2000s. Since 2003/2004 the improvement in the seismic network significantly reduced the possible underrecording of seismic sequences.
The catalog is accompanied by four supporting files. Supporting Material S1 is a table summary of all the events in the catalog, including a synoptic panel comparing the new catalog to the pre-existing catalogs. Supporting Material S2 is the collection of excerpts from the source documents, including the original figures and descriptions. Supporting Material S3 is the bibliography; a digital version of the literature sources referenced is available from the corresponding author. Supporting Material S4 is an addendum catalog that comprises the descriptions of a number of supplementary explosive events reported as anomalous in literature or monitoring files for various reasons, but not classified by us as paroxysms, major explosions, uncertain major explosions, or seismic sequences.
This catalog is complementary to the historical catalog Bevilacqua et al. (2020a), which comprises the years from 1879 to 1960. In the time interval between 1960 and 1970 no major explosions or paroxysms were recorded; however, some under-recording of major explosions might affect that decade. The modeling and estimation of inter-event time and temporal rate of major explosions and paroxysms at Stromboli volcano is detailed in Bevilacqua et al. (2020b) based on the data available at that time.
Finally, it is worth mentioning that the present catalog is based on the above reported criteria to characterize the ordinary activity, major explosions and paroxysms which are mostly oriented to the assessment of the hazard associated with the explosive activity of Stromboli. It should also be recognized that a well-defined boundary between these categories may not exist. The catalog is open and dynamic and welcomes contributions from other sources and new information in order to make it more complete and robust.Dipartimento della Protezione Civile, ItaliaPublishedOSV1: Verso la previsione dei fenomeni vulcanici pericolos
Hydrothermal Seismic Tremor in a Wide Frequency Band: The Nonvolcanic CO2 Degassing Site of Mefite d’Ansanto, Italy
No full textMefite d’Ansanto (Italy) is a nonvolcanic field characterized by persistent strong degassing
activity. A seismic field monitoring carried out during the Summer 2021 reveals a persis-
tent, extended, and complex source of seismic tremor characterized by a spectrum with a
frequency content from about 1 Hz to more than 35 Hz. While at frequency smaller than
3 Hz the signal amplitude is stationary, in the intermediate frequency band (3–20 Hz) sud-
den changes of amplitude are often observed, suggesting the existence of an intermittent
source (every few minutes to tens of minutes). Furthermore, very short bursts of high-fre-
quency energy are recognized in the tremor signal. Results of array analysis and seismo-
logical observation indicate that the sources of the analyzed tremor are located in a small
area centered on the main vent of the degassing area. The persistent low-frequency
tremor and the intermediate frequency signals propagate as surface waves to the seismic
stations installed around the source and indicate a very shallow source. On the contrary,
impulsive signals at frequencies greater than 20 Hz propagate as body waves, revealing a
deeper source likely located between 50 and 100 m depth.Published1102–1114JCR Journa
The performance of differential point positioning using low-cost GNSS in comparison to DInSAR for monitoring coseismic displacement of the Provenzana–Pernicana fault system (Mt. Etna, 2018 December eruptive phase)
No full textMt. Etna is a perfect laboratory for testing new approaches and new technologies in a very active geodynamic environment. It offers, in fact, the opportunity for measuring active crustal deformation, related to volcanic activity as well as to seismic faulting on its flanks. In this work, a network of low-cost/low-power Global Navigation Satellite System stations has been installed and tested on Mt. Etna, across a very active fault, the Provenzana–Pernicana system, cutting its north-eastern flank. During the test period, a lateral eruption occurred (starting on 2018 December 24), with a forceful dyke intrusion that stressed all the flanks of the volcano, soliciting all the main faults dissecting the edifice. Also the Provenzana–Pernicana fault system, where this network was recording, was activated during the dyke intrusion, producing a significant seismic swarm. The low-cost/low-power network data analysis allowed the fault slip during the intrusion to be clearly traced in time and space at all the stations lying on the hangingwall mobile block of the fault. All the stations lying south of the fault trace showed an eastward displacement, in very good agreement with the usual kinematics of the fault and the temporal duration of the M 3.5 December 24 earthquake, related to the seaward dislocation of the eastern mobile flank of the volcano, promoted and accelerated by dyke emplacement on the upper part of the edifice.Published1012-10232T. Deformazione crostale attivaJCR Journa
On the low-latitude NeQuick topside ionosphere mismodelling: The role of parameters H0, g, and r
No full textThis paper deals with the well-known mismodelling characterizing the NeQuick topside ionosphere at low latitudes, i.e., the fact that the model keeps the two electron density humps typical of the equatorial ionization anomaly as the altitude increases from the height of the F2-layer electron density peak, without merging them in a single peak above the geomagnetic equator as expected. This is because the NeQuick topside ionosphere modelling strongly depends on several bottomside ionosphere parameters, which causes an essential coupling between the topside and the bottomside that in many cases behave differently. This means that this kind of topside ionosphere modelling may lead to inaccurate results, as it is the maintenance at low latitudes of the electron density double hump structure in the topside as the altitude increases. On the base of some recently published results, this paper analyzes the role played by the three NeQuick scale height parameters H0, g and r in the description of the electron density above the F2 layer peak height. The results of this work pave the way for a possible solution of this low-latitude NeQuick topside ionosphere mismodelling.Published1224-12362A. Fisica dell'alta atmosferaJCR Journa