Istituto Nazionale di Geofisica e Vulcanologia

Timing and dynamic processes forming eruptible magma in crustal magma systems that feed highly explosive volcanic eruptions are encoded in compositional variations of magmatic crystals. The ca. 40 ka Campanian Ignimbrite deposit, the product of the most voluminous explosive eruption in the Campi Flegrei volcanic field, contains a variety of compositionally zoned sanidine pheno- and antecrysts. Barium diffusion chronometry was applied to 79 zoned sanidine crystals from different units and types of pumice clasts from the deposit. We focused on the compositional boundaries at the outermost rims of sanidine crystals considered to indicate mingling/mixing and recharge processes shortly prior to the eruption. Grey-scale swath profiles extracted from accumulated back-scattered electron images across these compositional discontinuities return diffusion times of mostly < 60 years at 902 °C that is the most appropriate estimated temperature. At ca. 850 °C, most times are between ca. 380 and 8 years; at ca. 970 °C, most estimates result to be < 4 years till 1 month. Our results indicate that resident magmas even in large, long-lived reservoirs such as the one that fed the Campanian Ignimbrite at Campi Flegrei, can be activated and become eruptible in relatively short timescales, comparable to those obtained for similar large silicic eruptions.

The nature of the long-term changes in the upper atmosphere morphology at mid-latitude remains a subject of debate, particularly regarding whether these changes are purely driven by geomagnetic and solar activities or whether forcing from the lower atmosphere, such as CO2 variations, may play a role. To contribute to this debate, we investigate the nature of the long-term trends of the ionospheric and thermospheric parameters by leveraging on ionosonde data digitally recorded at the Rome Observatory since 1976. The following parameters have been investigated under sunlit conditions (12:00 Local Time): critical frequency of the F1 layer (foF1); critical frequency of the F2 layer (foF2), atomic oxygen concentration at 300 km ([O]); ratio between atomic oxygen and molecular nitrogen concentrations at 300 km altitude ([O]/[N2]); exospheric temperature (Tex); thermospheric density at 300 km (ρ). The ionospheric parameters are manually scaled from digital ionograms, whereas thermospheric parameters are retrieved using the THERmospheric parameters from IONosonde observations (THERION) method, which utilises ionosonde observations and a physical model of the ionospheric F region. To investigate the influence of the solar and geomagnetic activity on long term variations, we consider the solar radio flux at 10.7 cm (F10.7) and the geomagnetic disturbance index Ap. To identify the various frequency/period components of the time series under consideration and identify the trends, we leverage the high scale/time resolution offered by the Fast Iterative Filtering (FIF) algorithm. A regression analysis of thermosphere/ionosphere parameters against geomagnetic/solar activity indices has then been conducted to investigate the drivers of long-term variability. Our findings reveal that the identified trends are predominantly controlled by external drivers, particularly long-term solar and geomagnetic activity variations. The adopted methodology, based on regression modelling, demonstrates that variability in F10.7 and Ap accounts for nearly all of the observed changes, with the exception of atomic oxygen ([O]), which displays a slightly higher unexplained variability (~7%). The inclusion of CO2 concentration as an additional driver improves the regression model for [O]. However, the effect remains statistically limited, indicating that the impact of CO2 on thermospheric cooling might be of little significance. Further studies with extended time series are necessary to better quantify this relationship and evaluate its importance. These results highlight the predominant influence of solar and geomagnetic activity in determining upper atmosphere long-term trends at mid-latitudes.

We present slip versus time histories derived from in situ ³⁶Cl cosmogenic dating for three active normal faults in the southern Apennines, Italy. In this region the total extensional strain is accommodated by either a small number of faults located across strike from each other or, in places, a single fault where no other active faults exist across strike. We investigate how strain‐rates on individual faults vary through time in the context of the overall geometry of the fault system. The ³⁶Cl results confirm that the San Gregorio Magno, Auletta, and Vallo di Diano faults were active in the Holocene, with each fault exhibiting alternating periods of relatively rapid and slow, or even absence of, slip. During periods of rapid slip, lasting a few millennia, the faults accumulate up to ∼5 m of slip, which we interpret as earthquake clusters. At other times, the faults exhibit no slip for time periods lasting multiple millennia. The fluctuations in slip‐rates reveal the migration of activity between faults and out‐of‐phase behavior. Such fluctuations have important consequences for tectonic evolution and crustal rheology, and in particular for hazard estimation because they introduce considerable variability and hence uncertainty in earthquake probability calculations.

We share long term, continuous measurements of soil radon emanations in Italy acquired from 2009 to 2021 by the Italian Radon mOnitoring Network (IRON). The radon concentrations were measured at 62 stations and consist of 621 720 single measurements. Employed detectors are both in-house prototypes (LUCAS) and commercial devices (AER by Algade©), suitably calibrated at INGV radionuclide laboratory. In addiction to radon concentration, most stations acquire internal temperature, while a subset of them also record relative humidity. When available, all these data series are provided along with radon time series and consist of 1 320 710 local temperature and humidity data. The presented dataset allows monitoring variations in radon emissions on multiple time scales, using different analysis techniques. Potential investigations include the effect of environmental parameters/conditions on radon emissions, the study of the impact on such emissions of transient signals like those associated with seismic and volcanic preparation processes and fluid migration dynamics as well as analyses of risk for human health, related to prolonged exposure to radon gas accumulated in confined spaces.

We present Bedmap3, the latest suite of gridded products describing surface elevation, ice-thickness and the seafloor and subglacial bed elevation of the Antarctic south of 60 °S. Bedmap3 incorporates and adds to all post-1950s datasets previously used for Bedmap2, including 84 new aero-geophysical surveys by 15 data providers, an additional 52 million data points and 1.9 million line-kilometres of measurement. These efforts have filled notable gaps including in major mountain ranges and the deep interior of East Antarctica, along West Antarctic coastlines and on the Antarctic Peninsula. Our new Bedmap3/RINGS grounding line similarly consolidates multiple recent mappings into a single, spatially coherent feature. Combined with updated maps of surface topography, ice shelf thickness, rock outcrops and bathymetry, Bedmap3 reveals in much greater detail the subglacial landscape and distribution of Antarctica’s ice, providing new opportunities to interpret continental-scale landscape evolution and to model the past and future evolution of the Antarctic ice sheets.

The complex stratigraphic setting of alternating volcanic and fluvial–lacustrine sedimentary deposits in the surroundings of Castel Cellesi village (Latium region, central Italy) offers an unprecedented opportunity to examine the influence of glacio-eustatic forcing on the depositional processes during Pleistocene times in the upper catchment of the Tiber River, in the inland sector of the Tyrrhenian Sea margin of Italy. Tight geochronologic constraints on the timing of sediment deposition have been established through precise ⁴⁰ Ar/ ³⁹ Ar dating of intervening volcanic layers. These new age constraints reveal a clear chronological correlation between sediment aggradation phases and sea-level rises, as evidenced by the δ ¹⁸ O record and relative sea-level (RSL) curve. The analysis of pyroclastic-flow deposits within incised paleo-valleys further indicates a relationship between periods of erosion or non-deposition and sea-level lowstands. Specifically, twelve ⁴⁰ Ar/ ³⁹ Ar dates have delineated three successive aggradational fluvial–lacustrine successions deposited during the sea-level rises of Marine Isotope Stages (MIS) 13, 11, and 9, as well as the erosional features associated with the sea-level drops of MIS 12 and 10. Graphical abstract 40 Ar/39Ar age constraints on the timing of sediment deposition reveal a direct chronological correlation between sediment aggradation phases and sea-level rises, as evidenced by the benthic Oxygen isotopes curve.

Plain Language Summary The continents on Earth move away from each other forming a rift valley. It is commonly accepted that the rift valley forms from fracturing of the Earth, forming geological faults which make a low lying downfaulted rift valley. The fracturing and faulting cause the rift to get wider through time. However, many rift valleys such as in East Africa have many active volcanoes, below which molten rock called magma moves from depth. The role and behavior of the magma in potentially helping the rift to grow and evolve is not well understood. In this study we map the motions of the Earth's surface during intense earthquake activity in September–November 2024 at a volcano (Fentale) in Ethiopia, using satellite images and seismograph recordings. The information shows that a roughly 14 km long blade of magma was injected from the volcano into the rift, widening it 2 m in a few weeks. The results suggest that rapid motion of magma every few hundred years helps continents to divide.

The Upper Jurassic aspidoceratoid genus Hybopeltoceras Olóriz is very scarcely recorded, and distributed only in the Cordillera Betica (Spain), Southern Alps (Italy) and in the Central Apennines (Italy). From rocks of the Lower Tithonian, with particular reference to the Hybonotum s.s. Subzone, of the Upper Bugarone Formation in Mount Lacerone (Rieti, Sabine Apennines, Italy), the new species Hybopeltoceras olorizi is described here on the basis of a giant macroconch. The specimen is well preserved, that allows to add new data to the original Olóriz diagnosis of the genus and shows a unique morphology making the ammonite very easy to recognise. The new species shows a set of clearly recognisable phenotypical aspects strongly affected by the “Platform Effect” (sensu Olóriz). The study of calcareous nannoplankton confirm the biostratigraphic attribution.

On behalf of the authors and readers of Reviews of Geophysics (RoG), the American Geophysical Union, and the broader scientific community, the editors wish to wholeheartedly thank those who reviewed manuscripts for RoG in 2024.

The electrically readable complex dynamics of robust and scalable magnetic tunnel junctions (MTJs) offer promising opportunities for advancing neuromorphic computing. In this work, we present an MTJ design with a free layer and two polarizers capable of computing the sigmoidal activation function and its gradient at the device level. This design enables both feedforward and backpropagation computations within a single device, extending neuromorphic computing frameworks previously explored in the literature by introducing the ability to perform backpropagation directly in hardware. Our algorithm implementation reveals two key findings: (i) the small discrepancies between the MTJ-generated curves and the exact software-generated curves have a negligible impact on the performance of the backpropagation algorithm, (ii) the device implementation is highly robust to inter-device variation and noise, and (iii) the proposed method effectively supports transfer learning and knowledge distillation. To demonstrate this, we evaluated the performance of an edge computing network using weights from a software-trained model implemented with our MTJ design. The results show a minimal loss of accuracy of only 0.4% for the Fashion MNIST dataset and 1.7% for the CIFAR-100 dataset compared to the original software implementation. These results highlight the potential of our MTJ design for compact, hardware-based neural networks in edge computing applications, particularly for transfer learning.

Effective discrimination between earthquakes and explosions is pivotal, particularly in the context of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) verification regime. This paper introduces the usage of a Support Vector Machine (SVM) algorithm tailored to discern seismic records produced by natural earthquakes from those caused by underground nuclear tests, wherein the registered values of mb and Ms magnitudes (body-wave and surface-wave magnitudes respectively) of each event are selected as feature vectors. These magnitude values are directly provided in official bulletins for each seismic event, therefore, no preliminary calculations were necessary, making our method easy to implement. By harnessing a diverse dataset and employing state-of-the-art machine learning algorithms, our approach demonstrates remarkable accuracy in discriminating these events. Also, we provide a posterior probability that estimates the correctness of the prediction performed by the classification algorithm. This work represents a significant stride towards enhancing the capabilities of seismic monitoring systems, thereby reinforcing international efforts towards nuclear non-proliferation and global stability.

The Alto Tiberina fault (ATF) in the Northern Apennines of Italy is one of the most extensively monitored low‐angle normal faults (LANFs) worldwide, hosting The Alto Tiberina Near Fault Observatory (TABOO‐NFO). The down‐dip geometry, mechanical properties, and kinematics of the ATF have been revised based on a new 10‐year (2010–2020) earthquake catalog. The dense configuration of TABOO‐NFO seismic network enabled a low detection threshold, resulting in a catalog of almost 100,000 events with ML < 3.9 and completeness magnitude ≈0.1 in ML scale, with high‐resolution hypocentral locations determined using an optimized 1D velocity model and newly estimated static station corrections. The distribution and kinematics of microseismicity within the ATF fault zone confirm the presence of locked portions along the main LANF plane. Stress build‐up in the locked shallow parts of the ATF results in the development of minor antithetic and splay structures with well‐oriented slip planes in the hanging‐wall, hosting small seismic sequences. In the deeper parts of the fault, creep may be facilitated by low‐friction lithologies, which are thought to promote stable slip. Clustering analysis further shows that the seismic activity of the ATF system evolves predominantly as swarms rather than as main shock‐aftershock sequences, highlighting the role of aseismic creep and stress distribution pattern in controlling seismicity. Our findings provide a major insight into the mechanics of LANFs and emphasize the importance of including both the primary fault and its secondary structures in seismic hazard models, with implications for other creeping fault systems worldwide.

In this study, we analyze the ionospheric and thermospheric changes from three coronal mass ejections (CMEs) that triggered a composite geomagnetic storm on 4-5 November 2023 with two activity periods. The first CME arrival on 4 November resulted in moderate activity (SYM-H=-60 nT), while two CMEs that arrived on 5 November caused intense geomagnetic disturbances (SYMH=-188 nT). Using global observations of vertical total electron content (VTEC) and the normalized VTEC storm-time index, we examine ionospheric anomalies during these events. Additionally, we use satellite observations of thermospheric composition, temperature and density, along with ionosonde-derived estimations of the large-scale traveling ionospheric disturbances velocities. Our results show that initial ionospheric changes in both activity periods were driven by prompt penetration electric fields, leading to positive VTEC anomalies. However, the delayed effects were vastly different. Due to weak high-latitude heating, the negative phase in 4 November event was largely inhibited. In contrast, on 5 November, high-latitude thermospheric heating was significant and led to strong decreases in the O/N2 ratios and setup global disturbance winds, causing severe negative VTEC anomalies. Despite weaker overall effects in VTEC, the moderate 4 November event caused a much more pronounced degradation of the GNSS availability due to stronger auroral scintillations. Our results underscore the highly dynamic nature of the ionosphere-thermosphere system and showcase that even similarly driven and temporally close events can nevertheless produce markedly different ionospheric responses. Notably, events with weaker geomagnetic activity can pose greater hazard and need to be carefully monitored to mitigate their potential impacts.

Vulcano Island (Aeolian Archipelago, southern Italy) is an active volcanic system exhibiting persistent fumarolic activity over decades, sustained by magmatic degassing. Geophysical and geochemical monitoring, carried out since the 1980s, intensified in autumn 2021 due to volcanic unrest. This study reports original geochemical data including the chemical composition of (i) fluid discharges from La Fossa crater and Baia di Levante coastal area, and (ii) water and dissolved gases from Vulcano Porto village. Using these data we reconstruct the physicochemical processes controlling the compositional evolution of fluids discharged from the hydrothermal/magmatic system. Over 2013–2023, the temporal patterns in the SO2/H2S and (HCl + HF)/H2S ratios of emitted gases (which are sensitive to the relative influence of magmatic degassing vs. hydrothermal activity), showed that in January–November 2021 a remarkable pulse of magmatic fluids were emitted from the fumaroles of the summit crater. In contrast, gas discharges located in the inner flank of the crater displayed no notable compositional changes and a decrease of outlet temperatures, indicating a partial sealing of the fumarolic conduits. These results suggest a differential response of the fumarolic field to the stress caused by the magmatic fluid input. Geothermometric computations in organic gas compositions (the light alkenes-alkanes systems) indicate increasing temperatures at depth starting in 2018 up to the beginning of the unrest. These results suggest that organic gases are useful geoindicators for the geochemical monitoring of this volcano. The results of this study have shown that fluids from the Baia di Levante responded to the magmatic fluid pulse with a delay of several months that was due to heat buffering and high-temperature gas dissolution within the hydrothermal reservoir feeding the fluid discharges. From early 2022, magmatic gases (SO2, HCl, HF) and estimated temperatures based on H2, CO, and light hydrocarbons from the crater fumaroles indicated a decrease in the input of magmatic fluids, mimicking the events of the 2004–2005 aseismic volcanic crisis at Teide volcano (Canary Islands, Spain). For the peripheral gas discharges, temperature-sensitive gas species registered a remarkable decrease in reservoir temperatures almost 1 year later than the crater fumaroles, in agreement with the delayed response to the magmatic pulse that affected the hydrothermal-dominated system of Baia di Levante. During the 2012–2016 eruptive cycle at Copahue volcano (Argentina), distal geothermal gas emissions recorded a similar delayed response to a magmatic pulse of distal fluid discharges relative to those from the main active crater. These results suggest that peripheral hydrothermal discharges are less useful for volcano monitoring. Although gas emissions are not back to pre-crisis background, the temporal trends of the geochemical parameters sensitive to magmatic fluid inputs, evidenced at both the summit of La Fossa crater and the Baia di Levante, suggest that the 2021 unrest at Vulcano appears to be weaker than that recorded in the late 1980s. Therefore, unless significant magma injection occurs, we anticipate that Vulcano Island will return to a relatively quiet status of activity typical of the decade prior to 2021.

The exploitation of the St. Gallen geothermal reservoir in Switzerland induced a seismic sequence lasting from July 2013 to October 2013. The sequence was characterized by 346 earthquakes located at a depth ranging between 4.4 and 4.7 km, having magnitude ranging between (−1.2, 3.5). We study the seismic source properties of the induced earthquakes by implementing both the individual earthquake displacement spectral inversion and an empirical Green's function‐based method that allows to reduce the trade‐off between source parameters and anelastic attenuation. We find a scaling between corner frequency and seismic moment down to 5 × 10¹⁰ Nm that differs from the generally assumed M0 ∝ fc⁻³. The retrieved average value of the static stress drop (3.8 MPa) is close to the median global value (4 MPa) observed for tectonic earthquakes and it is a small fraction (0.1%–20%) of the shear stress resolved on the fault planes. Moreover, we find that the analyzed events are characterized by low Savage‐Wood efficiency indicating a positive dynamic overshoot suggesting that only a small fraction of the available strain energy is radiated seismically.

The onset of a large explosive volcanic eruption is generally characterised by a weak transient activity. The products of this opening phase(s) are confined to thin proximal beds of small volume and limited dispersal. The juvenile material erupted in the opening phase provides a unique record of pre- and syn-eruptive processes and preserves key information on eruption triggering and dynamics during magma ascent. The study of these products can provide insights into precursory phenomena and assumes a key role for the interpretation of monitoring signals at high-risk volcanoes. In this work, we present a detailed study of the products from the opening phase of the Avellino Plinian eruption of Somma-Vesuvius (Italy), well preserved in proximal deposits as two sub-units of thin pumice lapilli fallout overlain by a fine ash bed. These deposits show textural and compositional variability of the juvenile material, depicting a complex process of magma extraction at the onset of the eruption. Geochemical, textural, and geobarometric data reveal the presence of a magma body at shallow depth that cooled and partially crystallised under different conditions compared to the main, deeper, and larger magma reservoir feeding the paroxysmal phases of the eruption. Elemental diffusion chronometry on clinopyroxene from juvenile material suggests that magma movement toward the shallow reservoir anticipated the eruption by a maximum of a hundred years, while the arrival of a last mafic input into the shallow magma body can be confined to only a few years before the eruption.