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Decomposing solar and geomagnetic activity and seasonal dependencies to examine the relationship between GPS loss of lock and ionospheric turbulence
No full textIonospheric irregularities are plasma density variations that occur at various altitudes and latitudes and whose size ranges from a few meters to a few hundred kilometers. They can have a negative impact on the Global Navigation Satellite Systems (GNSS), on their positioning accuracy and even cause a signal loss of lock (LoL), a phenomenon for which GNSS receivers can no longer track the satellites' signal. Nowadays, the study of plasma density irregularities is important because many of the crucial infrastructures of our society rely on the efficient operation of these positioning systems. It was recently discovered that, of all possible ionospheric plasma density fluctuations, those in a turbulent state and characterized by extremely high values of the Rate Of change of the electron Density Index appear to be associated with the occurrence of LoL events. The spatial distributions of this class of fluctuations at mid and high latitudes are reconstructed for the first time using data collected on Swarm satellites between July 15th, 2014 and December 31st, 2021, emphasizing their dependence on solar activity, geomagnetic conditions, and season. The results unequivocally show that the identified class of plasma fluctuations exhibits spatio-temporal behaviours similar to those of LoL events.Published9287OSA3: Climatologia e meteorologia spazialeJCR Journa
Seismic and thermal precursors of crater collapses and overflows at Stromboli volcano
No full textLava overflows are highly hazardous phenomena that can occur at Stromboli. They can destabilize the crater area and the "Sciara del Fuoco" unstable slope, formed by several sector collapses, which can generate potentially tsunamigenic landslides. In this study, we have identified precursors of the October-November 2022 effusive crisis through seismic and thermal camera measurements. We analyzed the lava overflow on October 9, which was preceded by a crater-rim collapse, and the overflow on November 16. In both cases, seismic precursors anticipating the overflow onset have been observed. The analysis of the seismic and thermal data led to the conclusion that the seismic precursors were caused by an escalating degassing process from the eruptive vent, which climaxed with the overflows. Volcano deformation derived from ground-based InSAR and strainmeter data showed that inflation of the crater area accompanied the escalating degassing process up to the beginning of the lava overflows. The inflation of the crater area was especially evident in the October 9 episode, which also showed a longer seismic precursor compared to the November 16 event (58 and 40 min respectively). These results are important for understanding Stromboli's eruptive mechanisms and open a perspective for early warning of potentially dangerous phenomena.This work has been supported by the INGV project Pianeta Dinamico 2023-2025 - ObseRvation, Measurement and modelling of Eruptive processes (ORME), and partially supported by the Progetto Strategico Dipartimentale INGV 2019 “Forecasting eruptive activity at Stromboli volcano: timing, eruptive style, size, intensity and duration” (FIRST, Delibera n. 144/2020; Scientific Responsibility: S.C.). Furthermore, this research has benefited from the support of Convenzione B2 DPC-INGV 2022-2024, Stromboli, Task 1.3 “Development of a unique activity index and estimation of the probability of the transition between ‘ordinary’ and ‘extraordinary’ eruptive activity”, and of the INGV project Reti Multiparametriche, Task A2 “Development of methods for the identification of precursors of Stromboli’s paroxysms and major explosions based on multiparametric data analysis and study of possible early warning techniques”. The data used in this study were provided by the Istituto Nazionale di Geofisica e Vulcanologia (Osservatorio Vesuviano, Osservatorio Etneo) and by the Centro per la Protezione Civile, Università degli Studi di Firenze (GBInSAR data). We would also like to acknowledge the support of the Italian Dipartimento della Protezione Civile (DPC). It should be noted that this paper does not necessarily reflect the official opinion and policies of DPC.Published111154V. Processi pre-eruttiviJCR Journa
Shallow portion of an active geothermal system revealed by multidisciplinary studies: The case of Le Biancane (Larderello, Italy)
No full textThe natural park of Le Biancane is located in the southern sector of the Larderello-Travale geothermal field (LTGF). It extends over an approximately 100,000 m2 area where the impermeable caprock is locally absent and deep fluids may directly reach the surface. Through a multidisciplinary approach including measurements of soil CO2 flux (total output of 11.5 t day 1), soil temperature (average 34.4 ◦C), stable isotope and chemical data on fluids from fumaroles (dominated by a mixture of geothermal gases and air or gases from air-saturated meteoric water), and structural analysis of the formation outcropping, we found that anomalous CO2 emissions
are positively correlated with shallow temperature anomalies. These are in restricted locations adjacent to vents and fumaroles, where a network of well-connected fractures (preferentially NW-SE and NE-SW orientated and with steep dips) drains efficiently allowing upward migration of the deep fluids and the energy toward the surface.INGV Project RL 2021 - AGEREMUSPublished102616OSA5: Energia e georisorseJCR Journa
Natural iron fertilization by shallow hydrothermal sources fuels diazotroph blooms in the ocean
No full textIron is an essential nutrient that regulates productivity in ~30% of the ocean. Compared with deep (>2000 meter) hydrothermal activity at mid-ocean ridges that provide iron to the ocean's interior, shallow (<500 meter) hydrothermal fluids are likely to influence the surface's ecosystem. However, their effect is unknown. In this work, we show that fluids emitted along the Tonga volcanic arc (South Pacific) have a substantial impact on iron concentrations in the photic layer through vertical diffusion. This enrichment stimulates biological activity, resulting in an extensive patch of chlorophyll (360,000 square kilometers). Diazotroph activity is two to eight times higher and carbon export fluxes are two to three times higher in iron-enriched waters than in adjacent unfertilized waters. Such findings reveal a previously undescribed mechanism of natural iron fertilization in the ocean that fuels regional hotspot sinks for atmospheric CO2.Published812-8174A. Oceanografia e clima6A. Geochimica per l'ambiente e geologia medicaJCR Journa
A lithostratigraphic reappraisal of a Permian-Triassic fluvial succession at Allan Hills (Antarctica) and implications for the terrestrial end-Permian extinction event
No full textBetween Permian to Triassic, the Earth experienced climatic and biotic crises, included the greatest mass extinction at the Permian-Triassic boundary. These climatic and biological changes are reflected in both marine and terrestrial depositional systems. Over this time span, the Gondwana supercontinent hosted numerous large basins that may preserve the paleoenvironment response to global changes in the sedimentary record. This study provides a lithostratigraphic reappraisal of the latest Paleozoic-Mesozoic alluvial Beacon Supergroup at Allan Hills (Convoy Range), which is one of the most complete sedimentary sequences in Antarctica. Fieldwork stratigraphic-lithological observation, facies analysis, and petrographic characterization of sedimentary rocks allow the identification of six depositional units. The investigations point out for a conformable relationship between depositional and lithostratigraphic units, characterized by changes in the fluvial style. The reconnaissance of a “transitional interval” showing intermediate features between the Permian Weller Coal Measures and the Triassic Feather Conglomerate strengthen the conformable nature of the sequence across the Permian-Triassic boundary in this region. The lithological features of such interval strongly resemble those observed in the coeval deeply studied Eastern Australia successions crossing the Permian-Triassic boundary as well as the end-Permian extinction. More precisely, the uppermost coal occurrence, just above a glossopterid macroflora-bearing carbonaceous mudstone within the “transitional interval”, marks the disappearance of coal-peat forming Permian vegetation which corresponds with the terrestrial end-Permian extinction, thus representing one of the few end- Permian extinction records in Antarctica.Published111741OSA2: Evoluzione climatica: effetti e loro mitigazioneJCR Journa
Temporal Variations of Seismicity Rates and Gutenberg–Richterb-Values for a Stochastic Declustered Catalog: An Example in Central Italy
No full textOne important aspect of the seismicity is the spatiotemporal clustering; hence, the distinction between independent and triggered events is a critical part of the analysis of seismic catalogs. Stochastic declustering of seismicity allows a probabilistic distinction between these two kinds of events. Such an approach, usually performed with the epidemic‐type aftershock sequence (ETAS) model, avoids the bias in the estimation of the frequency–magnitude distribution parameters if we consider a subset of the catalog, that is, only the independent or the triggered events. In this article, we present a framework to properly include the probabilities of any event to be independent (or triggered) both in the temporal variation of the seismic rates and in the estimation of the b‐value of the Gutenberg–Richter law. This framework is then applied to a high‐definition seismic catalog in the central part of Italy covering the period from April 2010 to December 2015. The results of our analysis show that the seismic activity from the beginning of the catalog to March 2013 is characterized by a low degree of clustering and a relatively high b‐value, whereas the following period exhibits a higher degree of clustering and a smaller b‐value.Published1566–1578OST2 Deformazione e Hazard sismico e da maremotoJCR Journa
HV Noise and Earthquake Automatic Analysis (HVNEA)
No full textWe present HVNEA tool (HV Noise and Earthquake Automatic analysis), a software package to automatically compute the horizontal‐to‐vertical spectral ratios (HV) on continuous months‐to‐years recordings, including both earthquake and ambient noise vibration. It is designed for processing large data sets of seismic signals, for example, from long‐term permanent or temporary stations belonging to monitoring networks, using free software and packages that are commonly adopted in the engineering–seismology community. HVNEA is in the form of Linux‐Unix shell scripts and packaged in a Docker image to run the code in any environment. It is designed to automatically download data from the main international repositories or from a local archive. The main achievement consists of the average HV as a function of time and saved in ASCII format, along with attractive and readable graphic plots to easily inspect the results. The analysis highlights the variation of the HV over a long span of time. HVNEA software package can be of great interest for big data analysts and seismic network operators, with regard to the site characterization analysis and for studies based on temporal variability of HV ratios over time.Published350–3685T. Sismologia, geofisica e geologia per l'ingegneria sismicaJCR Journa
Monitoring sandy shorelines using SAR imagery and LiDaR measurements
No full textThis study is to demonstrate the ability of Cband Synthetic Aperture Radar (SAR) satellite data to extract the coastline and monitor coastal erosion against ancillary information extracted by the Unmanned Aerial System (UAS)based Light Detection and Ranging (LiDaR) measurements. Experiments are carried out on a key data set collected over the Ionian coast of Basilicata region, in the South of Italy. Preliminary results demonstrate the added-value provided in the framework of coastal area observation by integrating spaceborne radar and drone-based optical sensor technologies.Publishe
The San Bartolo lava flow field, Stromboli volcano, Italy: Reconstruction of the most recent historic flank eruption (2 kyr) affecting the inhabited area by photogrammetric and LIDAR from UASs aimed at hazard assessment
No full textThe San Bartolo lava flow field is the most recent flank eruption occurred at Stromboli volcano about 2 ka ago on the NE flank of the island. Despite its importance in being the most recent example of flank activity outside the barren Sciara del Fuoco slope, where the recent activity concentrated, the eruption duration, its volume, and the sequence of events has not yet been reconstructed. In this paper, we present a new survey of the lava flow field, carried out both on the field and photogrammetric and LIDAR surveys from UASs, in order to estimate the erupted lava volume and to reconstruct the sequence of events and infer a possible duration and impact of the eruption. The analysis of the surveys allowed us to verify the contact with previous lava flow fields, allowing a more precise lateral extension of the lava delta along the coast, as well as an estimation of the thickness and volume, at least for the subaerial portion of the lava flow field. The morphology analysis of the lava flow field allowed us to recognize structures suggesting inflation and then stationing of the lava flow fronts, features indicating a long-lasting eruption and a complex interaction with the sea. Our results can provide a useful scenario should a flank eruption occur in the future, a possibility that was close to happening in 1998, when the ground deformation stations revealed a lateral intrusion in the shallow supply system of the volcano.Publishe
How do inherited dip-slip faults affect the development of new extensional faults? Insights from wet clay analog models
No full textThe development of structurally controlled basins is frequently dominated by inherited geological and tectonic structures, especially when the affected region has undergone multiple tectonic phases. In this study we use physically scaled analog models to analyze the impact of inherited faults on the evolution of a new extensional fault system and its associated basin. In our experiments, we introduced inherited faults – bearing diverse geometries and orientations – cut through a homogeneous analog material (wet clay). After each experiment, we compare (a) how the inherited faults affected the inception and development of new faults and (b) the shape of the resulting basins, using a ‘reference model’ run without pre-existing faults. The results show that the orientation of pre-existing faults with respect to the extensional axis does affect the development of the new extensional structures. The main effects show up when the orientation of the pre-existing faults is closer to that expected for a fault that is optimally oriented (perpendicular) with respect to the direction of extension and has a dip close to an Andersonian extensional fault. Conversely, the impact on the resulting basin shape is more spatially complex, especially in the case of misoriented pre-existing faults. We also compare our experimental results with an analytical method based on the slip tendency theory. The application of our findings to selected natural cases demonstrates how one may interpret the occurrence, orientation, and activity of inherited faults by looking at the present-day geometry and wavelength of an extensional basin, particularly when newly formed extensional faults exhibit structurally unexpected trajectories.Part of this work was funded by the project “The impact of an inherited structural setting on the development of extensional systems in the Amatrice-Norcia-Visso area: insights from analog modeling” (UR 0865.050; P.I.: Umberto Fracassi), part of the INGV-FISR 2016 Project - Italia centrale “Centro di studio e monitoraggio dei rischi naturali dell'Italia centrale” (cod. D82F16001180001), and by the INGV “FASTMIT” Project (UR 0850.010; P.I.: Roberto Basili – cod. D52F16001150001).Published1048362T. Deformazione crostale attivaJCR Journa