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Against Båth’s Law: When Aftershocks Became Mainshocks—Implications for Earthquake Forecasting Communication
No full textThe Båth’s law is an empirical seismological relation between the magnitudes of the
mainshock and the largest aftershock of a seismic sequence. This empirical law, differently
from other seismological laws, could be valid only when the seismic sequence is ended.
Indeed, during the sequence, we don’t know if the strongest event has already happened
or not, and then inferring something about the magnitude of the largest aftershock is
hazardous. In this opinion paper, we discuss some issues related to the Båth’s law: its
validity on a global catalog, the use of the terms “mainshock” and “aftershock” in the
seismological community and in the public, and their implications in earthquake forecasting
communications. We show the uselessness of Båth’s law in earthquake forecasting, and
that the words “mainshock” and “aftershock” have different interpretations for the public
and for seismologists. We argue that their use during an ongoing seismic sequence,
without a proper explanation of their meaning, could be confounding, in particular for the
Italian language. Calling all events just “earthquakes” could be a simple but effective
solution.Published2565–2568OST4 Descrizione in tempo reale del terremoto, del maremoto, loro predicibilità e impattoJCR Journa
Potential for rupture before eruption at Campi Flegrei caldera, Southern Italy
No full textVolcanoes reawakening after long repose must rupture the crust before magma can erupt. Rupture is preceded by repeatable variations in the rate of seismicity with ground movement, which trace the amount of applied stress that is released by local earthquakes. A rupturing sequence has been developing across four episodes of ground uplift at Italy’s Campi Flegrei caldera: in 1950-1952, 1969-1972, 1982-1984 and since 2004. We predicted in 2016 that the approach to rupture would continue after an additional uplift of 30-40 cm at the location of largest movement. We have updated our analysis with new data on changes in the numbers of local earthquakes with amounts of ground movement. Here we show that subsequent events have confirmed our prediction and that the unrest has been changing the structure of Campi Flegrei’s crust. The results provide new constraints for evaluating the volcano’s potential to erupt or to subside without eruption.Published1904V. Processi pre-eruttiviJCR Journa
Paleoenvironmental changes related to the variations of the sea-ice cover during the Late Holocene in an Antarctic fjord (Edisto Inlet, Ross Sea) inferred by foraminiferal association
No full textTR17-08, a marine sedimentary core (14.6 m), was collected during 2017 from the Edisto Inlet (Ross Sea, Antarctica), a small fjord near Cape Hallett. The core is characterized by expanded laminated sedimentary sequences making it suitable for studying submillennial processes during the Early Holocene. By studying different well-known foraminifera species (Globocassidulina biora, G. subglobosa, Trifarina angulosa, Nonionella iridea, Epistominella exigua, Stainforthia feylingi, Miliammina arenacea, Paratrochammina bartrami and Portatrochammina antarctica), we were able to identify five different foraminiferal assemblages over the last ∼ 2000 years BP. Comparison with diatom assemblages and other geochemical proxies retrieved from nearby sediment cores in the Edisto Inlet (BAY05-20 and HLF17-1) made it possible to distinguish three different phases characterized by different environmental settings: (1) a seasonal phase (from 2012 to 1486 years BP) characterized by the dominance of calcareous species, indicating a seasonal opening of the inlet by more frequent events of melting of the sea-ice cover during the austral summer and, in general, a higher-productivity, more open and energetic environment; (2) a transitional phase (from 1486 to 696 years BP) during which the fjord experienced less extensive sea-ice melting, enhanced oxygen-poor conditions and carbonate dissolution conditions, indicated by the shifts from calcareous-dominated association to agglutinated-dominated association probably due to a freshwater input from the retreat of three local glaciers at the start of this period; and (3) a cooler phase (from 696 years BP to present) during which the sedimentation rate decreased and few to no foraminiferal specimens were present, indicating ephemeral openings or a more prolonged cover of the sea ice during the austral summer, affecting the nutrient supply and the sedimentation regime.Published95–115OSA2: Evoluzione climatica: effetti e loro mitigazioneJCR Journa
Environmental and Volcanic Implications of Volatile Output in the Atmosphere of Vulcano Island Detected Using SO2 Plume (2021–23)
No full textThe volatiles released by the volcanic structures of the world contribute to natural environmental pollution both during the passive and active degassing stages. The Island of Vulcano is characterized by solfataric degassing mainly localized in the summit part (Fossa crater) and in the peripheral part in the Levante Bay. The normal solfataric degassing (high-temperature fumarolic area of the summit and boiling fluids emitted in the Levante Bay area), established after the last explosive eruption of 1888–90, is periodically interrupted by geochemical crises characterized by anomalous degassing that are attributable to increased volcanic inputs, which determine a sharp increase in the degassing rate. In this work, we have used the data acquired from the INGV (Istituto Nazionale di Geofisica e Vulcanologia) geochemical monitoring networks to identify, evaluate, and monitor the geochemical variations of the extensive parameters, such as the SO2 flux from the volcanic plume
(solfataric cloud) and the CO2 flux from the soil in the summit area outside the fumaroles areas. The increase in the flux of volatiles started in June–July 2021 and reached its maximum in November of the same year. In particular, the mean monthly flux of SO2 plume of 22 tons day−1 (t d−1) and of CO2 from the soil of 1570 grams per square meter per day (g m2 d −1) increased during this event up to 89 t d−1 and 11,596 g m2 d −1, respectively, in November 2021. The average annual baseline value of SO2 output was estimated at 7700 t d−1 during normal solfataric activity. Instead, this outgassing increased to 18,000 and 24,000 t d−1 in 2021 and 2022, respectively, indicating that the system is still in an anomalous phase of outgassing and shows no signs of returning to the pre-crisis baseline values. In fact, in the first quarter of 2023, the SO2 output shows average values comparable to those emitted in 2022. Finally, the dispersion maps of SO2 on the island of Vulcano have been produced and have indicated that the areas close to the fumarolic source are characterized by concentrations of SO2 in the atmosphere higher than those permitted by European legislation (40 µg m−3
for 24 h of exposition) on human health.This research was funded by the INGV-DPCN (Italian National Institute of Geophysics
and Volcanology-Italian National Department for Civil Protection) volcanic surveillance program of
Vulcano island, ObFu 0304.010. Moreover, this investigation was partially funded by TORS project in
the framework of institutional INGV projects (“Ricerca Libera”, ObFu 9999.549 and Pianeta Dinamico
Task V2, ObFu 1020.010).Published30864V. Processi pre-eruttiviJCR Journa
GNSS-Interferometric Reflectometry, spectral artifacts and sea level measurements in the Mediterranean Sea
No full textTidal sea level variations in the Mediterranean basin, although altered and amplified by resonance phenomena in confined sub-basins (e.g., Adriatic Sea), are generally confined within 0.5 meters and exceptionally up to 1.5 meters. Here we explore the possibility to retrieve sea level measurements using data from GNSS antennas on duty for ground motion monitoring and analyze the spectral outcomes of such distinctive measurements. We estimate one year of GNSS data collected on the Mediterranean coasts in order to get reliable sea level data from all public-available data and compare it with collocated tide gauges. A total amount of eleven stations was suitable for interferometric analysis (as for 2021) and all were able to supply centimeter level sea level estimates. The spectra in the tidal frequency windows are remarkably similar to tide gauges data. We find that the O1 and M2 diurnal and semidiurnal tides and MK3, MS4 shallow sea water tides may be disturbed by aliasing effects.Published2358OST5 Verso un nuovo MonitoraggioOSA4: Ambiente marino, fascia costiera ed Oceanografia operativaN/A or not JC
The noble gas signature of the 2021 Tajogaite eruption (La Palma, Canary Islands)
No full textHere, we characterize the temporal evolution of volatiles during the Tajogaite eruption by analyzing the
elemental (He-Ar-CO2-N2) and isotopic (He-Ar-Ne) composition of fluid inclusions (FI) in phenocrysts (olivine+
pyroxene) identified in erupted lavas. Our 2021 lava samples identify substantial temporal variations in
volatile composition. We show that, during the 2021 Tajogaite eruption, the He-CO2-N2 concentrations in FI
increased since October 15th; this increase was accompanied by increasing 40Ar/36Ar ratios (from ~300 to
>500), and paralleled a major shift in bulk lava chemistry, with increasing Mg contents (Mg#, from 47 to 52 to
55–59), CaO/Al2O3 (from 0.65 to 0.74 to 0.75–0.90), Ni and Cr, and decreasing TiO2, P2O5 and incompatible
elements. The olivine core composition also became more forsteritic (from Mg# = 80–81 to Mg# = 84–86).
Mineral thermobarometry and FI barometry results indicate that the eruption was sustained by magmas previously stored in at least two magma accumulation zones, at respectively ~6–12 km and 15–30 km, corroborating previous seismic and FI evidence. We therefore propose that the compositional changes seen throughout the eruption can be explained by an increased contribution - since early/mid-October - of more primitive, less degassed magma from the deeper (mantle) reservoir. Conversely, Rc/Ra values (3He/4He ratios corrected for atmospheric contamination) remained constant throughout the whole eruption at MORB-like values (7.38 ± 0.22 Ra, 1σ), suggesting an isotopically homogeneous magma feeding source. The Tajogaite He isotope signature is within the range of values observed for the 1677 San Antonio lavas (7.37 ± 0.17Ra, 1σ), but is more radiogenic than the 3He/4He values (>9 Rc/Ra) observed in the Caldera de Taburiente to the north. The 3He/4He ratios (6.75 ± 0.20 Ra, 1σ) measured in mantle xenoliths from the San Antonio volcano indicate a relatively radiogenic nature of the mantle beneath the Cumbre Vieja ridge. Based on these results and mixing modeling calculations, we propose that the homogeneous He isotopic signatures observed in volatiles from the Tajogaite/San Antonio lavas reflect three component mixing between a MORB-like source, a radiogenic component and small additions (6–15%) of a high 3He/4He reservoir-derived (>9Ra) fluid components. The simultaneous occurrence of high 3He/4He (>9Ra)- and MORB-like He signatures in northern and southern La Palma is interpreted to reflect small-scale heterogeneities in the local mantle, arising from spatially variable proportions of MORB, radiogenic, and high 3He/4He components.Published107928OSV2: Complessità dei processi vulcanici: approcci multidisciplinari e multiparametriciJCR Journa
Multi-GPU multi-resolution SPH framework towards massive hydrodynamics simulations and its applications in high-speed water entry
No full textWe propose a multi-phase, multi-resolution SPH method for fluid/solid interaction with multi-GPU implementation and dynamic load balancing following the movement of the refinement regions. The primary design goal of this framework is to maintain the efficiency of the single-resolution SPH model running on a single GPU. To this end, a multi-background mesh is introduced, and the domain is regarded as a nested multi-domain with different resolutions. Validation using both a δ-SPH and Riemann SPH model is shown, and applications to the simulation of the water entry of a projectile with a high Froude number are considered, with comparisons to experimental data from three challenging test cases, showing the proposed model's ability to correctly reproduce the free surface evolution on water entry, the motion of the projectile, and the formation and evolution of multiple cavities depending on entry angle and velocity. An analysis of the computational performance and resolutions achieved (up to 120 million particles) is also provided across several test cases.Published112339JCR Journa
Geochemistry of thermal springs and associated gases along the Strymon River Valley (Bulgaria and Greece)
No full textThis paper presents and discusses the water and gas geochemistry of a large number of thermal springs occurring along the N-S trending Strymon Valley, from its source, near Sofia (Bulgaria), to the Aegean Sea (Greece). In Bulgaria springs have markedly alkaline pH, relatively low Total Dissolved Solids and prevalent Na-HCO3 to Na-Cl(SO4) in composition while the associated gas phase is mostly N2-dominated. When moving to the Greek sector, the thermal springs, Ca(Mg)-HCO3 to Na-HCO3, become less alkaline and more saline whereas the associated gas phase is CO2-dominated. The abrupt geochemical change in the Greek sector is caused by a variation in the thickness and nature of the sediments filling the Strymon Valley, the latter being characterized by a relevant amount of Neogene marine material. Such changes occur south of an important E-W lineament named Middle Mesta, south of which marble formations extensively crop out and are likely occurring below the sedimentary succession. The presence of these carbonate sequences embedded in the Neogene sediments is explaining the CO2-rich gases associated to the Greek springs. Water isotopes indicate a meteoric origin for the studied waters. From a geothermometric point of view, solute (previous studies) and gas (this work) geothermometers suggest that no high enthalpy systems occur in the Bulgaria and northern sector of Greece with estimated temperatures <120 °C. Consequently, these thermal springs can be regarded as tectonically-derived along the many fault systems that border the Strymon Valley. The convective circuits are thus originated from rainfall in the crystalline massifs that border the valley, i.e. the Serbo-Macedonian to the west and the Rhodope to the east.Published107262OSA5: Energia e georisorseJCR Journa
Electron density fluctuations from Swarm as a proxy for ground-based scintillation data: A statistical perspective
No full textThe Swarm satellite mission has been used for numerous studies of the ionosphere. Here we use a global product, based on electron density measurements from Swarm that characterises ionospheric variability. The IPIR (Ionospheric Plasma IRregularities product) provides characteristics of plasma irregularities in terms of their amplitudes, gradients and spatial scales and assigns them to geomagnetic regions. Ionospheric irregularities and fluctuations are often the cause of errors in position, navigation, and timing (PNT) based on the Global Navigation Satellite Systems (GNSS), in which signals pass through the ionosphere. The IPIR dataset also provides an indication, in the form of a numerical value index (IPIR index), of the severity of irregularities affecting the integrity of trans-ionospheric radio signals and hence, the accuracy of GNSS positioning. We analysed datasets from Swarm A and ground-based scintillation receivers. Time intervals (when Swarm A passes over the field of view of the ground-based GPS receiver) are compared to ground-based scintillation data, collecting an azimuthal selection of the GNSS data relevant to the Swarm satellite overpass. We provide validations of the IPIR product against the ground-based measurements from 23 ground-based receivers, focusing on GPS TEC and scintillation data in low-latitude, auroral and polar regions, and in different longitudinal sectors. We have determined the median, mean, maximum and standard deviation of the parameter values for both datasets and each conjunction point. We found a weak correlation of the intensity of both phase and amplitude scintillation with the IPIR index.Published5399-5415OSA3: Climatologia e meteorologia spazialeJCR Journa
EuroGOOS roadmap for operational coastal downstream services
No full textThe EuroGOOS Coastal working group examines the entire coastal value chain
from coastal observations to services for coastal users. The main objective of the
working group is to review the status quo, identify gaps and future steps needed
to secure and improve the sustainability of the European coastal service
provision. Within this framework, our white paper defines a EuroGOOS
roadmap for sustained “community coastal downstream service” provision,
provided by a broad EuroGOOS community with focus on the national and
local scale services. After defining the coastal services in this context, we
describe the main components of coastal service provision and explore
community benefits and requirements through sectoral examples
(aquaculture, coastal tourism, renewable energy, port, cross-sectoral) together
with the main challenges and barriers to user uptake. Technology integration
challenges are outlined with respect to multiparameter observations, multiplatform
observations, the land-coast-ocean continuum, and multidisciplinary data integration. Finally, the technological, financial, and institutional sustainability of coastal observing and coastal service provision are discussed.
The paper gives special attention to the delineation of upstream and
downstream services, public-private partnerships and the important role of
Copernicus in better covering the coastal zone. Therefore, our white paper is a
policy and practice review providing a comprehensive overview, in-depth
discussion and actionable recommendations (according to key short-term or
medium-term priorities) on the envisaged elements of a roadmap for sustained
coastal service provision. EuroGOOS, as an entity that unites European national
operational oceanography centres, research institutes and scientists across
various domains within the broader field of operational oceanography, offers to
be the engine and intermediary for the knowledge transfer and communication
of experiences, best practices and information, not only amongst its members,
but also amongst the different (research) infrastructures, institutes and agencies
that have interests in coastal oceanography in Europe.Published11776154A. Oceanografia e climaJCR Journa