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Investigation of Ionospheric Small‐Scale Plasma Structures Associated With Particle Precipitation
No full textWe investigate the role of auroral particle precipitation in small-scale (below hundreds of meters) plasma structuring in the auroral ionosphere over the Arctic. In this scope, we analyze together data recorded by an Ionospheric Scintillation Monitor Receiver (ISMR) of Global Navigation Satellite System (GNSS) signals and by an All-Sky Imager located in Longyearbyen, Svalbard (Norway). We leverage on the raw GNSS samples provided at 50 Hz by the ISMR to evaluate amplitude and phase scintillation indices at 1 s time resolution and the Ionosphere-Free Linear Combination at 20 ms time resolution. The simultaneous use of the 1 s GNSS-based scintillation indices allows identifying the scale size of the irregularities involved in plasma structuring in the range of small (up to few hundreds of meters) and medium-scale size ranges (up to few kilometers) for GNSS frequencies and observational geometry. Additionally, they allow identifying the diffractive and refractive nature of fluctuations on the recorded GNSS signals. Six strong auroral events and their effects on plasma structuring are studied. Plasma structuring down to scales of hundreds of meters is seen when strong gradients in auroral emissions at 557.7 nm cross the line of sight between the GNSS satellite and receiver. Local magnetic field measurements confirm small-scale structuring processes coinciding with intensification of ionospheric currents. Since 557.7 nm emissions primarily originate from the ionospheric E-region, plasma instabilities from particle precipitation at E-region altitudes are considered to be responsible for the signatures of small-scale plasma structuring highlighted in the GNSS scintillation data.Publishede2023SW003605OSA3: Climatologia e meteorologia spazialeJCR Journa
The Preparation Phase of the 2023 Kahramanmaraş (Turkey) Major Earthquakes from a Multidisciplinary and Comparative Perspective
No full textOn 6 February 2023, Turkey experienced its most powerful earthquake in over 80 years, with a moment magnitude (Mw) of 7.7. This was then followed by a second earthquake of Mw 7.6 just nine hours later. According to the lithosphere–atmosphere–ionosphere coupling (LAIC) models, such a significant seismic activity is expected to cause anomalies across various observables, from the Earth’s surface to the ionosphere. This multidisciplinary study investigates the preparatory phase of these two major earthquakes by identifying potential precursors across the lithosphere, atmosphere, and ionosphere. Our comprehensive analysis successfully identified and collected various anomalies, revealing that their cumulative occurrence follows an accelerating trend, either exponential or power-law. Most anomalies appeared to progress from the lithosphere upward through the atmosphere to the ionosphere, suggesting a sequential chain of processes across these geospheres. Notably, some anomalies deviated from this overall trend, manifesting as oscillating variations. We propose that these anomalies support a two-way coupling model preceding major earthquakes, highlighting the potential role of fluid chemistry in facilitating these processes.Published2766OST4 Descrizione in tempo reale del terremoto, del maremoto, loro predicibilità e impattoJCR Journa
Geophysical Responses to an Environmentally‐Boosted Volcanic Unrest
No full textThe spatiotemporal relationship between geophysical, environmental, and geochemical responses during volcanic unrest is essentially unknown, making their joint use and interpretation for eruption forecasting challenging. Here, Empirical Orthogonal Functions analysis applied to GPS data allows the separation of the
dominant deep‐sourced inflation from environmentally controlled signals associated with extension at Campi
Flegrei caldera. This separation bridges the gap between deformation, seismic and geochemical responses,
clarifying the processes underlying the ongoing volcanic unrest. Persistent meteoric forcing during the 2017–
2018 hydrological year changed the decadal trend of seismic energy and secondary deformation components,
pairing their spatial patterns. The result was a block in the carbon dioxide released in 2018 at Solfatara, the
primary stress‐release valve at the caldera. The subsequent overpressure weakened the fractured eastern caldera, opening pathways for deep, hot materials to reach the surface. Our results give insight into how environmental forcing can favor volcanic unrest in pressurized calderas.Publishede2023GL104895OSV2: Complessità dei processi vulcanici: approcci multidisciplinari e multiparametriciJCR Journa
Exploring Rare Earth Element behavior in the Mount Etna volcanic aquifers (Sicily)
No full textThis study presents the first data on REY (Rare Earth Elements plus Yttrium) in the aquifer of Mount Etna (Sicily, Italy). Patterns normalized to chondrites indicate strong water-rock interaction, facilitated by a slightly acidic pH resulting from the dissolution of magma-derived CO2. REY patterns provide insights into the processes of both mineral dissolution and the formation of secondary phases. The relative abundance of light to heavy rare earth elements is compatible with the prevailing dissolution of ferromagnesian minerals (e.g., olivine or clinopyroxenes), reinforced by its strong correlation with other proxies of mineral dissolution (e.g., Mg contents). Pronounced negative Ce anomalies and positive Y anomalies demonstrate an oxidizing environment with continuous formation of secondary iron and/or manganese oxides and hydroxides. The Y/Ho fractionation is strongly influenced by metal complexation with bicarbonate complexes, a common process in C-rich waters. In the studied system, the measured REY contents are always below the limits proposed by Sneller et al. (2000, RIVM report, Issue 601,501, p. 66) for surface water and ensure a very low daily intake from drinking water.Published237JCR Journa
Investigating the Role of Fluids in the Source Parameters of the 2013–2014 Mw 5 Matese Seismic Sequence, Southern Italy
No full textWe investigate the variability of Brune stress drop (Δσ), apparent stress (τa), and Savage–
Wood radiation efficiency (ηsw
τa= Δσ), in the 2013–2014 Mw 5.0 earthquake sequence
that struck the Matese area in the southern Apennines range of Italy. The sequence is
clustered in a relatively small crustal volume in the 13–22 km depth range, which is
greater than that of background seismicity and normal-faulting sequences that occurred
under the range axis, usually located in the first 15 km of the crust.We find high Savage–
Wood radiation efficiency values for most of the analyzed earthquakes located in a narrow
crustal volume, with values ranging from well above the self-similarity value to very
high values as high as 0.55. In addition, a large variability in radiation efficiency (up to
90%) is observed for two similar magnitude events at different depths. Previous studies
reported seismic evidence of fluid involvement in the nucleation process of the Matese
earthquakes. By integrating our results with crustal geophysical data published recently,
we propose that most of the earthquakes characterized by high values of ηsw are
nucleated within high pore pressure zones located in the crystalline midcrust of Adria.
We reckon that high pore pressure fluids of deep origin played a role in the rupture process
and were responsible for themixed shear-tensile sources inferred from the analysis of
the S-wave/P-wave spectral amplitude ratio for most of 2013–2014 earthquakes.Published299–319JCR Journa
Geohydrologic units of Ischia Island (Southern Tyrrhenian Sea, Italy)
No full textThe first hydrogeological mapping of Ischia Island at the 1:10,000 scale is presented and
discussed. The ‘Map of the geohydrologic units of Ischia Island’ and the accompanying
hydrostratigraphic sequence at a basin scale are based on the most recent geological
maps and data from the CAR.G Project, and on new volcanological and hydrogeological
surveys and studies. Data sources include the database stored by the INGV, Sezione di
Napoli, Osservatorio Vesuviano and field investigations, including a survey of the springs
and thermo-mineral springs which has been neglected up to now. In total 130
volcanostratigraphic units and 18 geohydrologic units were recognized; the distribution of
fumaroles sites was enhanced, and 60 springs/thermal springs were identified/rediscovered.
The proposed hydrogeological map provides an overview of the volcano-tectonic evolution
of Ischia Island and upgrades the hydrogeological model, becoming a catalyst for the effort
to acquire better data and to manage natural both resources and risks.Published2317142OSV2: Complessità dei processi vulcanici: approcci multidisciplinari e multiparametriciJCR Journa
Coastal Groundwater Bodies Modelling Using Geophysical Surveys: The Reconstruction of the Geometry of Alluvial Plains in the North-Eastern Sicily (Italy)
No full textThe integration of various geophysical methodologies is considered a fundamental tool for
accurately reconstructing the extent and shape of a groundwater body and for estimating the physical
parameters that characterize it. This is often essential for the management of water resources in areas
affected by geological and environmental hazards. This work aims to reconstruct the pattern and
extent of two groundwater bodies, located in the coastal sectors of the North-Eastern Sicily, through
the integrated analysis and interpretation of several geoelectrical, seismic and geological data. These
are the Sant’Agata-Capo D’Orlando (SCGWB) and the Barcelona-Milazzo (BMGWB) Groundwater
Bodies, located at the two ends of the northern sector of the Peloritani geological complex. These two
studied coastal plains represent densely populated and industrialized areas, in which the quantity
and quality of the groundwater bodies are under constant threat. At first, the resistivity models of
the two groundwater bodies were realized through the inversion of a dataset of Vertical Electrical
Soundings (VES), constrained by stratigraphic well logs data and other geophysical data. The 3D
resistivity models obtained by spatially interpolating 1D inverse VES models have allowed for an
initial recognition of the distribution of groundwater, as well as a rough geological framework of the
subsoil. Subsequently, these models were implemented by integrating results from active and passive
seismic data to determine the seismic P and S wave velocities of the main lithotypes. Simultaneous
acquisition and interpretation of seismic and electrical tomographies along identical profiles allowed
to determine the specific values of seismic velocity, electrical resistivity and chargeability of the
alluvial sediments, and to use these values to constrain the HVSR inversion. All this allowed us to
recognize the areal extension and thickness of the various lithotypes in the two investigated areas
and, finally, to define the depth and the morphology of the base of the groundwater bodies and the
thickness of the filling deposits.Published1048JCR Journa
Depth and Spatial Variation of the Shear Wave Attenuation Parameters in the Shallow Crust and Lower Crust/Upper Mantle of Mt. Etna (Italy)
No full textSeismic wave attenuation is a key feature of seismic
wave propagation that provides constraints on the composition and
physical state of the medium within the Earth. We separated
intrinsic and scattering attenuation coefficients for the shallow crust
and lower crust/upper mantle in the Mt. Etna area. For this purpose,
the Multiple Lapse Time Window Analysis (MLTWA) was applied
to two groups of earthquakes, well separated in depth. We also
studied the spatial variation of the attenuation parameters by
dividing the study area into four sectors around Etna. The results
show an effective homogeneity of the propagation characteristics
inside Etna and, in particular, some lateral variations and minor
variations with depth. We observe that structural discontinuities
and lithology control scattering losses at all frequencies, with
higher scattering in the shallow crust. The intrinsic absorption
shows no sensitivity to the presence of these main geological
structures and is quite uniform for different depths. Furthermore,
compared to the northern sector of the volcano, the southern one
shows stronger scattering attenuation at low frequencies. This
pattern correlates well with the high seismic activity along most of
Etna’s active tectonic structures and ascending magmatic fluids that
characterize this sector of the volcano. Although we only discuss
the differences in the ‘‘average’’ scattering and inelastic properties
of the investigated volumes, the results of this study are very
informative about the characteristics of each region. Moreover,
they suggest that a future study is necessary, providing a more
detailed picture of the spatial distribution of seismic attenuation in
the study area, through a 3D inversion of the attenuation parameters
estimated along the single source-receiver paths.Published171–187OSV2: Complessità dei processi vulcanici: approcci multidisciplinari e multiparametriciJCR Journa
Non-linear elasticity, earthquake triggering and seasonal hydrological forcing along the Irpinia fault, Southern Italy
No full textPump-probe experiments investigate the strain sensitivity of crustal elastic properties, showing nonlinear variations during the strain cycle. In the laboratory, pre-seismic reductions in seismic velocity indicate that asperity contacts within the fault zone begin to fail before the macroscopic frictional sliding. The recognition of such effects in natural seismic-cycles has been challenging. Here we exploit seasonal hydrological strains, performing a natural analogue to a quasi-static laboratory pump-probe experiment to investigate the nonlinear strain sensitivity of crustal rocks and its role in seismic failure along the tectonically-active Irpinia Fault System (Southern Italy). By comparing 14-years-long series of spring discharge, strain, seismic velocity variations and earthquakes rate, we find that seismicity peaks during maximum hydrological forcing and minimum seismic velocity. Seasonal strains of ~10-6 are required for both earthquake triggering and significant nonlinearity effects arising from modulus reduction. We suggest that, for faults in a critical state, cyclical softening may lead to failure and seasonal seismicity.Published9821JCR Journa
Space Weather Impact on Radio Communication and Navigation
No full textIt is well known that space weather can cause significant disruptions to modern communications and navigation systems, leading to increased safety risks, economic losses, and reduced quality of life. Operators of critical infrastructures (both national and international) are also increasingly aware that extreme space-weather events can have severe impacts on their systems. For example, strong ionospheric disturbances can degrade, and sometimes deny access to satellite positioning, navigation, and timing services, central to the operation of many infrastructures. The mitigation of the effects of space weather on technical systems on the ground and in space, and the development of possible protective measures, are therefore of essential importance. We discuss how space weather drives a wide variety of ionospheric phenomena that can disrupt communications and navigation systems and how scientific understanding can help us to mitigate those effects. We also provide recommendations on further research and collaboration with industrial and governmental partners, which are essential for the development and operation of space weather services.In pressOSA3: Climatologia e meteorologia spazialeJCR Journa