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Temporal variability of explosive activity at Tajogaite volcano, Cumbre Vieja (Canary Islands), 2021 eruption from ground-based infrared photography and videography
No full textThe 2021 eruption at Tajogaite (Cumbre Vieja) volcano (La Palma, Spain)
was characterized by Strombolian eruptions, Hawaiian fountaining, white gasdominated and grey ash-rich plumes, and lava effusion from multiple vents.
The variety of eruptive styles displayed simultaneously and throughout the
eruption presents an opportunity to explore controls on explosivity and the
relationship between explosive and effusive activity. Explosive eruption dynamics
were recorded using ground-based thermal photography and videography. We
show results from the analysis of short (<5 min) near-daily thermal videos taken
throughout the eruption from multiple ground-based locations and continuous
time-lapse thermal photos over the period November 16 to November 26. We
measure the apparent radius, velocity, and volume flux of the high-temperature
gas-and-ash jet and lava fountaining behaviors to investigate the evolution of the
explosive activity over multiple time scales (seconds-minutes, hours, and daysweeks). We find fluctuations in volume flux of explosive material that correlate
with changes in volcanic tremor and hours-long increases in explosive flux that
are immediately preceded by increases in lava effusion rate. Correlated behavior
at multiple vents suggests dynamic magma ascent pathways connected in the
shallow (tens to hundreds of meters) sub-surface. We interpret the changes in
explosivity and the relative amounts of effusive and explosivity to be the result of
changes in gas flux and the degree of gas coupling.Authors from INVOLCAN and ITER acknowledge
support under projects VOLRISKMAC (MAC/3.5b/124) and
VOLRISKMAC II (MAC2/3.5b/328), financed by the Program
INTERREG V-A Spain-Portugal MAC 2014–2020 of the European
Commission; Cumbre Vieja Emergencia, financed by the Science
and Innovation Ministry, Spanish Government; TFassistance,
financed by the Cabildo Insular de Tenerife; and LPvolcano, financed
by the Cabildo Insular de La Palma. We are grateful to Antoni
Álvarez for his logistical support. Authors from LDEO acknowledge
support from the Gordon and Betty Moore Foundation under
grant GBMF8995 for the AVERT project, and from NSF under
EAR-1654588.Published11934365V. Processi eruttivi e post-eruttiviJCR Journa
Equatorial plasma bubble intensities across longitudinal sectors of the globe using GNSS observations
No full textWe present the first investigation of Equatorial Plasma Bubble (EPB) intensities across longitudinal sectors of the globe using observations from global navigation satellite system (GNSS) receivers. GNSS data from a total of 93 receiver stations located within ±20 degrees of the geomagnetic equator across the globe were used. The data covered periods of years 2014 and 2019 which are respectively years of high and low solar activity in solar cycle 24. We define a parameter known as the Standard deviation of Residual TEC (SRT) to characterize the EPB intensities. The EPB occurrence was defined by day-night differences of the rate of change of TEC index (ROTI). We observed a high correlation (r ∼ 0.80) between the magnitudes of the SRT and ROTI during the EPB occurrence, but the correlation is low (r ∼ 0.37) during non occurrence of EPB. The EPB intensities are greater during seasons with high occurrence rates. The EPB intensities and occurrence rates are also greater during the high solar activity. We found that the post-sunset intensities are greatest in the Atlantic region, followed by the African region, then the American, Australian, Asian, and Pacific regions in that order. The post-midnight intensities are greatest in the African region, followed by the Atlantic, American, Australian, Asian, and Pacific regions in that order.Published106097OSA3: Climatologia e meteorologia spazialeJCR Journa
Machine Learning and Microseism as a Tool for Sea Wave Monitoring
No full textMonitoring the state of the sea is a fundamental task for economic activities in the coastal zone, such as transport, tourism and infrastructure design. In recent years, regular wave height monitoring for marine risk assessment and mitigation has become unavoidable as global warming impacts in more intense and frequent swells.In particular, the Mediterranean Sea has been considered as one of the most responsive regions to global warming, which may promote the intensification of hazardous natural phenomena as strong winds, heavy precipitation and high sea waves. Because of the high density population along the Mediterranean coastlines, heavy swells could have major socio-economic consequences. To reduce the impacts of such scenarios, the development of more advanced monitoring systems of the sea state becomes necessary.In the last decade, it has been demonstrated how seismometers can be used to measure sea conditions by exploiting the characteristics of a part of the seismic signal called microseism. Microseism is the continuous seismic signal recorded in the frequency band of 0.05 and 0.4 Hz that is likely generated by interactions of sea waves together and with seafloor or shorelines.In this work, in the framework of i-WaveNET INTERREG project, we performed a regression analysis to develop a model capable of predicting the sea state in the Sicily Channel (Italy) using microseism, acquired by onshore instruments installed in Sicily and Malta. Considering the complexity of the relationship between spatial sea wave height data and seismic data measured at individual stations, we used supervised machine learning (ML) techniques to develop the prediction model. As input data we used the hourly Root Mean Squared (RMS) amplitude of the seismic signal recorded by 14 broadband stations, along the three components, and in different frequency bands, during 2018 - 2021. These stations, belonging to the permanent seismic networks managed by the National Institute of Geophysics and Volcanology INGV and the Department of Geosciences of the University of Malta, consist of three-component broadband seismometers that record at a sampling frequency of 100 Hz.As for the target, the significant sea wave height data from Copernicus Marine Environment Monitoring Service (CMEMS) for the same period were used. Such data is the hindcast product of the Mediterranean Sea Waves forecasting system, with hourly temporal resolution and 1/24° spatial resolution. After a feature selection step, we compared three different kinds of ML algorithms for regression: K-Nearest-Neighbors (KNN), Random Forest (RF) and Light Gradient Boosting (LGB). The hyperparameters were tuned by using a grid-search algorithm, and the best models were selected by cross-validation. Different metrics, such as MAE, R2 and RMSE, were considered to evaluate the generalization capabilities of the models and special attention was paid to evaluate the predictive ability of the models for extreme wave height values.Results show model predictive capabilities good enough to develop a sea monitoring system to complement the systems currently in use.UnpublishedVienn
Hydrothermal signature on episodic deflation/inflation ground tilt at Aso Volcano
No full textGround deformation in volcanic areas induced by geothermal fluid circulation can reveal useful information about the dynamical processes occurring in the subsurface hydrothermal system. In the present work, we investigate tiltmeter time-series recorded at Aso Volcano during 2011–2016, a time interval during which different phases of volcanic activity occurred. We performed polarization analysis of the data and identified peculiar long-lasting (hours) transients, defined as Very-Long-period Tilt Pulses. The transients were further characterized in terms of waveform cross-correlation, particle tilt pattern, energy, and time distributions. The analyses indicate that such signals, which appear like deflation–inflation (DI) events, are associated with a Poissonian process whose underlying dynamics evolves over time always driven by a Poissonian mechanism. The obtained results have been interpreted in light of the available geophysical, geochemical and volcanological information. In this framework, the Very-Long-period Tilt Pulses may be ascribed to the depressurization/pressurization of the shallow hydrothermal system according to a fault-valve mechanism, which was active with different efficiency throughout eruptive and inter-eruptive phases.Published1324V. Processi pre-eruttiviJCR Journa
Minor earthquakes in the asolo area (1861-1921)
No full textThe need to improve hazard assessments with more up-to-date basic data is also supported by the awareness of how important the seismicity of an area is in the perspective of risk assessment. Although the occurrence of strong earthquakes is decisive for these assessments, increasing weight in the latest hazard models is given to information on intermediate and moderate energy earthquakes.
This study consists of a comprehensive review of the information available for six 'minor' earthquakes that occurred in the Treviso area close to the Venetian Prealps, in particular the area close to Asolo, in the chronological span of 1861-1921. The area under examination, which from a seismic characterization point of view can be identified as 'Pedemontana Sud' (Sugan and Peruzza, 2011), presents various reasons of interest from many angles: physical, geological (just think of the presence of the Montello massif) and landscape. It is a particularly important industrial and craft district, with a significant economic weight and exposed value, represented by the density of the population and the settlement network.
From the preliminary studies available, research was carried out ex novo, going back to the original sources and redetermining the epicentral parameters of each event on a new basis. In particular, the earthquakes taken into consideration are those of 19 May 1861, 14 April 1887, 11 June 1897, 4 March 1900, 12 July 1919, and 12 September 1921, all included in the CPTI15 catalogue (Rovida et al., 2022) based on preliminary studies and therefore not very in-depth. Since this is a work on earthquakes of relatively moderate energy, which occurred in a very specific area and fall within a defined historical period, the problems that the historical study must address are far from irrelevant. Indeed, there is not a lot of information available, making the work of verifying and interpreting the data very complex and affected by considerable uncertainties.Published.OST1 Alla ricerca dei Motori Geodinamic
Quantification of gas, ash, and sulphate aerosols in volcanic plumes from open path Fourier transform infrared (OP-FTIR) emission measurements at Stromboli volcano, Italy
No full textField-portable Open Path Fourier Transform Infrared (OP-FTIR) spectrometers
can be used to remotely measure the composition of volcanic plumes using
absorption spectroscopy, providing invaluable data on total gas emissions.
Quantifying the temporal evolution of gas compositions during an eruption
helps develop models of volcanic processes and aids in eruption forecasting.
Absorption measurements require a viewing geometry which aligns infrared
source, plume, and instrument, which can be challenging. Here, we present a
fast retrieval algorithm to estimate quantities of gas, ash and sulphate aerosols
from thermal emission OP-FTIR measurements, and the results from two pilot
campaigns on Stromboli volcano in Italy in 2019 and 2021. We validate the
method by comparing time series of SO2 slant column densities retrieved using
our method with those obtained from a conventional UV spectrometer,
demonstrating that the two methods generally agree to within a factor of 2.
The algorithm correctly identifies ash-rich plumes and gas bursts associated
with explosions and quantifies the mass column densities and particle sizes of
ash and sulphate aerosols (SA) in the plume. We compare the ash sizes retrieved
using our method with the particle size distribution (PSD) of an ash sample
collected during the period of measurements in 2019 by flying a Remotely
Piloted Aircraft System into the path of a drifting ash plume and find that both
modes of the bimodal PSD (a fine fraction with diameter around 5–10 μm and a
coarse fraction around 65 μm) are identified within our datasets at different
times. We measure a decrease in the retrieved ash particle size with distance
downwind, consistent with settling of larger particles, which we also observed
visually. We measure a decrease in the SO2/SA ratio as the plume travels
downwind, coupled with an increase in measured SA particle size (range
2–6 μm), suggesting rapid hygroscopic particle growth and/or SO2 oxidation. We propose that infrared emission spectroscopy can be used to
examine physical and chemical changes during plume transport and opens the
possibility of remote night-time monitoring of volcanic plume emissions. These
ground-based analyses may also aid the refinement of satellite-based aerosol
retrievals.Published1005738OSV2: Complessità dei processi vulcanici: approcci multidisciplinari e multiparametriciJCR Journa
Origin of Seismicity in Italy as a Clue for Seismic Hazard
No full textItalianseismicityisgeneratedbytheongoingsubductionoftheEuro- pean lithosphere beneath the Alps, and the Adriatic lithosphere beneath the Apen- nines. The two belts are extremely different due to their opposite polarity relative to the inferred underlying ‘eastward’ mantle flow. Contractional tectonics is con- centrated in low topography areas, whereas extensional tectonics and the larger magnitude seismicity due to normal faulting is preferentially located along the Apennines ridge, where the brittle crustal layer is thicker and the lithostatic load is maximum. Seismicity is the result of dissipation of energy along passive faults but stored mostly in crustal volumes located in the hangingwall of the faults. The 2–5 mm/yr deformation in all Italian tectonic settings prevents the occurrence of great earthquakes (Mw 8) that rather occur in other areas of the world where deformation rates are at least one order of magnitude faster. The maximum event so far recorded in Italy is Mw 7.3, 1693 southeast Sicily. InSAR data nowadays provide a precise definition of the epicentral area of an earthquake, which can be several hundred km2. The epicentral area is defined as the ‘active’ domain where the hangingwall is moving along the fault and it is contemporaneously crossed by the seismic waves radiated by the fault plane due to the friction in it. Within the active domain occur the strongest coseismic shaking, both vertical and horizontal. The vertical coseismic motion allows the horizontal shaking to be much more effective.Published168-1804T. Sismicità dell'Itali
Propagation of Perturbations in the Lower and Upper Atmosphere over the Central Mediterranean, Driven by the 15 January 2022 Hunga Tonga-Hunga Ha’apai Volcano Explosion
No full textThe Hunga Tonga-Hunga Ha’apai volcano (Pacific Ocean) generated a cataclysmic explosion
on 15 January 2022, triggering several atmospheric disturbances at a global scale, as a huge
increase in the total electron content (TEC) in the ionosphere, and a pressure wave travelling in the
troposphere. We collected and analysed data over the Mediterranean to study these disturbances, and
in particular, (i) data from the barometric and infrasonic stations installed on Italian active volcanoes
by the Istituto Nazionale di Geofisica e Vulcanologia (INGV) for investigating the tropospheric pressure
waves; (ii) barometric data from the INGV-TROPOMAG and SIAS (Sicilian Agro-meteorological
Information System) networks, for investigating the interaction between the orography and pressure
waves; (iii) ionograms from the Advanced Ionospheric Sounder-INGV ionosonde at Gibilmanna
(Sicily, Italy); (iv) data from the RING (Rete Italiana Integrata GNSS) network, to retrieve the ionospheric
TEC; (v) soil CO2 flux data from the INGV surveillance network of Vulcano Island. The
analysis of the ground-level barometric data highlights that pressure waves were reflected and
diffracted by the topographic surface, creating a complex space–time dynamic of the atmospheric
disturbances travelling over Sicily, driven by the interference among the different wavefronts. The
ionograms show that a medium-scale travelling ionospheric disturbance (MSTID), with a horizontal
wavelength of about 220 km and a period of about 35 min, propagated through the ionospheric
plasma in the correspondence of the first barometric variations. Moreover, comparing detrended TEC
and barometric data, we further confirmed the presence of the aforementioned MSTID together with
its close relation to the tropospheric disturbance.Published652A. Fisica dell'alta atmosferaJCR Journa
Towards a Cloud Model Choice Evaluation: comparison between Cost/Features and Ontology-based analysis
No full textIn academic institutions, there is frequently the need to provide new services, in a cloud model, to be used either in teaching or research activities. One of the main decisions to be addressed is related to the cloud model to adopt (private, public or hybrid), and what the mixing of functionalities to use for the hybrid one. In this paper two different methodologies (Cost/features and Semantic-based) are been experimented in order to identify the best suited cloud model to adopt for a specific problem.
The long-term perspective is to build a methodology to serve as a tool to be used as decision support for the ICT manager in order to help him in this decision. The comparison between the two different methodologies show the strengths and weaknesses of both approaches.Published15-283IT. Calcolo scientificoJCR Journa
Historical explosive activity of Mount Melbourne Volcanic Field (Antarctica) revealed by englacial tephra deposits
No full textFive tephra layers named BRH1 to 5 were sampled in an ice cliff located on the north-eastern flank of Mount Melbourne (northern Victoria Land, Antarctica). The texture, componentry, mineralogy, and major and trace element compositions of glass shards have been used to characterize these layers. These properties suggest that they are primary fall deposits produced from discrete eruptions that experienced varying degrees of magma/water interaction. The major and trace element glass shard analyses on single glass shards indicate that Mount Melbourne Volcanic Field is the source of these tephra layers and the geochemical diversity highlights that the eruptions were fed by compositionally diverse melts that are interpreted to be from a complex magma system with a mafic melt remobilizing more evolved trachy-andesitic to trachytic magma pockets. Geochemical compositions, along with textural and mineralogical data, have allowed correlations
between two of the englacial tephra and distal cryptotephra from Mount Melbourne, recovered within a marine sediment core in the Edisto Inlet (~ 280 km northeast of Mount Melbourne), and constrain the age of these englacial tephra layers to between the third and the fourth century CE. This work provides new evidence of the intense historical explosive activity of the Mount Melbourne Volcanic Field and better constrains the rates of volcanism in northern Victoria Land. These data grant new clues on the eruptive dynamics and tephra dispersal, and considerably expand the geochemical (major and trace elements) dataset available for the Mount Melbourne Volcanic Field. In the future, this will facilitate the precise identification of tephra layers from this volcanic source and will help define the temporal and spatial correlation between
Antarctic records using tephra layers. Finally, this work also yields new valuable time-stratigraphic marker horizons for future dating, synchronization, and correlations of different palaeoenvironmental and palaeoclimatic records across large regions of Antarctica.Published391V. Storia eruttiva5V. Processi eruttivi e post-eruttiviJCR Journa