Giorgio Lacanna

Open‐vent volcanoes are characterized by the persistent activity of outgassing, lava effusion and mild explosions, which is, however, occasionally interrupted by more violent explosive activity (paroxysm), for example, Stromboli (Italy). In spite of the different (two orders of magnitude) explosive intensities and different petrological magma source, regular explosive activity and paroxysms share the same inflation pattern of ground deformation. We show that this similar ground deformation pattern is also reflecting a common pressurized shallow reservoir of gas‐poor, crystal‐rich stagnant magma source located at 280 m depth beneath the eruptive vent. We demonstrate that this source can also explain the ground deformation recorded during flank effusive eruptions, suggesting that both explosive and effusive dynamics are involving the same shallow magmatic system. We propose a fluid mechanical model of a basaltic conduit that correlates a geodetically‐derived pressure change of the shallow reservoir and eruptive phenomena at the vent. The pressure changes corresponding to the ground inflation before explosive eruptions (regular “Strombolian” explosion and paroxysm) and deflation during lava effusion are compatible with the magma volume discharged during each eruption, whereas a dynamic pressure caused by viscous magma flow in the conduit can be used to infer the final inflation velocity of the magma surface before the paroxysm.

Stromboli, Italy, is a unique volcano worldwide with near‐continuous eruptions monitored by a multi‐sensor network. Between 2019 and 2021, three events produced pyroclastic density currents along the Sciara del Fuoco that entered the sea and generated tsunamis, providing a unique data set linking flow dynamics to tsunami generation near the source. We compare these field observations—first crest amplitude, trough and full waveform—with laboratory experiments to assess lab‐to‐field upscaling and predictive reliability of volcanic‐flow tsunamis. Using key dimensionless parameters, we show that existing experiments overestimate relative flow mass, limiting direct scaling to Stromboli events and motivating new experiments. An empirical scaling for experimental pyroclastic flows entering water, however, predicts satisfactorily observed tsunami amplitudes. Both laboratory and field data also reveal a consistent three‐wave pattern, enabling the development of predictive relationships for the trough‐to‐amplitude ratio of the leading wave and total waveform energy. This study marks a first step toward bridging laboratory developments with field observations, opening new paths for volcanic‐tsunami hazard assessment.

Ordinary, moderately explosive activity at Stromboli is sporadically interrupted by larger effusive and explosive events that can trigger hazardous phenomena such as sector collapses, tsunamis, and ballistic fallout. We analyze 25 years of satellite infrared data to characterize the thermal pattern associated with these larger events, including: (1) effusive eruptions, (2) lava overflows, (3) major explosions, and (4) paroxysms. Increased heat flux precedes effusive eruptions and overflow sequences, and is interpreted to reflect the progressive rise of the magma column in the conduit accompanying the transition between Strombolian and effusive regimes. Conversely, major explosions are not preceded by any detectable thermal increase, although they statistically occur during periods of frequent overflows in which the Volcanic Radiative Power (VRP) is punctuated by higher values. Paroxysms (which occurred at the beginning, during and at the end of the effusive eruptions) do not show systematic thermal patterns in the preceding days, but in most cases are followed by a VRP increase. Major explosions and paroxysmal events contribute minimally to the long-term energy released by the volcano. Instead, the energy output is primarily governed by the recurrent transitions between Strombolian- and effusive-dominated regimes, sustaining a long-term, steady-state VRP of approximately 14.5 MW. Overall, only ~ 25% of the thermal energy is radiated during Strombolian activity, whereas overflows and effusions account for ~ 15% and ~ 60%, respectively. Results highlight that satellite thermal analysis is a useful tool for tracking changes of surface activity at open-vent basaltic volcanoes with frequent switching from ordinary low-energy activity to more energetic explosive or effusive eruptions.

The San Niccolò’ Tower-Gate in Florence, designed by Andrea dell’Orcagna, was built in 1328 as part of the third ring of the city walls of Florence. In the frame of a conservation project promoted by the Municipality of Florence, Belle Arti Office, the Department of Earth Sciences of the University of Florence conducted a series of studies, using NDT and LDT (No Destructive Test, Low Destructive Test) techniques, to characterize the tower’s masonry. The knowledge path followed the Italian Guide Line emitted by the Ministry of Culture for the conservation of historical buildings and the principles established by the International Restoration Charts. This knowledge path had already been tested and followed for the study of several other historical Florentine cultural heritage buildings. The first step regards the geometric survey and the 3D H-BIM restitution. Particular attention had been paid to the geological and foundation setting as an integral part of the building and to the local seismicity, too. The definition of the masonry structure and assemblages had been performed by using seismic, georadar, sonic, and sclerometric investigations. The Tower-Gate’s masonry results showed it to be very well constructed, being in the standard of the historical Florentine buildings of that time. After eight centuries since its construction, the San Niccolò’ Tower-Gate displays a good conservation condition according to the principles of Integrity and Authenticity.

The San Niccolò’ Tower-Gate in Florence, designed by Andrea dell'Orcagna, was built in 1328 as part of the third ring of the city walls of Florence. In the frame of a conservation project promoted by the Municipality of Florence, the Department of Earth Sciences of the University of Florence conducted a series of studies, using NDT techniques, to characterize the tower's masonry. Based on geological, seismic, georadar, sonic, and scleometric investigations, the Tower's masonry was found to had been excellently constructed and, after eight centuries, remains in good condition.

A labeled data set of 216,681 infrasound detections was compiled using data from the Central and Eastern European Infrasound Network (CEEIN). Detections associated with quarry blasts, thunderstorms, eruptions of the Etna volcano, industrial activity, and the war in Ukraine were categorized using ground truth information, such as seismic and lightning data. To establish benchmark performance, a random forest classifier and a convolutional neural network (CNN) were trained separately, achieving F1 scores of 0.8170 and 0.8248 on the test set, respectively. An ensemble model, combining both classifiers, outperformed them achieving an F1 score of 0.8773. The model, initially trained on four CEEIN arrays, was tested on data from a separate station not included in training. Although performance initially declined, transfer learning and fine‐tuning of the CNN and retraining the random forest model improved the ensemble model's F1 score to 0.9056 making it a considerable step. These results represent significant progress in automatic infrasound signal classification for monitoring the atmosphere.

Since 2019, the frequency of major explosive eruptions at Stromboli volcano (Italy) has increased, heightening the exposure of population and scientists to the hazards posed by ejecta. Morphological changes can directly alter the hazard potential associated with these phenomena. Here, we present a quantitative morphological analysis of changes of the crater terrace area linked to the 13 May 2022 major explosive event. High resolution (2.5 cm pixel-1) aerial imagery was acquired by unoccupied aircraft systems 2 hours before and 19 hours after the event. The 13 May 2022 major explosive event consisted of a minimum of seven explosions from four vents located in the south-central crater area. The opportune timing of this campaign enabled the quantification of morphological changes at Stromboli related to a single major explosive event at high temporal and spatial resolution. A total of 12.7 × 103 m3 was excavated and 5.5 × 103~m3 deposited. Via the mapping and classification of bomb distributions we observe that angular blocks make up the largest fraction of ballistics >0.2 m, from which we infer a strong interaction with wall rock and/or fragmentation of solidified plugs in the shallow plumbing system. The morphological changes observed provide valuable constraints on how much material is displaced, and the shift in location and the number of active vents during major explosive events at Stromboli.