Multidisciplinary geophysical study of the NE sector of the unstable flank of Etna volcano

On volcanic areas, usually characterized by complex structural environments, a lot of independent geophysical studies are usually performed. The non-uniqueness of the geophysical inverse models, the different level of reso- lution and sensitivity of the results spurred us to integrate independent geophysical datasets and results collected on Mt. Etna volcano, in order to obtain more accurate and reliable model interpretation. Mt. Etna volcano is located along the eastern coast of Sicily and it is characterized by a complex structural set- ting. In this region, the general N-S compressive regime related to the Africa – Europe collision interacts with the WNW-ESE extensional regime associated to the Malta Escarpment dynamics, observable along the eastern coast of Sicily. At Mt Etna, a great number of studies concerns the existence of instability phenomena; a general eastward mo- tion of the eastern flank of the volcano has been measured with always increasing detail and its relationship with the eruptive and magmatic activity is being investigated. The unstable flank appears bounded to the north by the E–W-trending Provenzana - Pernicana Fault System and to the SW by the NS Ragalna Fault system. Eastwards, this area is divided by several NW–SE trending faults. Recent studies consider this area as divided into several blocks characterized by different shape and kinematics. Ground deformation studies (GPS and InSAR) define the NE portion of the unstable flank as the most mobile one. In the frame of the MEDiterranean Supersites Volcanoes (MED-SUV) project, ground deformation data (GPS and INSAR), 3D seismicity, seismic tomography and two resistivity model profiles, have been analyzed together, in order to put some constraints on the deep structure of the NE sector of the unstable flank. Seismic data come from the permanent network run by the Istituto Nazionale di Geofisica e Vulcanologia (INGV) - Sezione di Catania, Osservatorio Etneo. Ground deformation data comes from InSAR Permanent Scatterers analyses of different spaceborn sensors. The resistivity models come from a MT survey carried out on the eastern flank of the volcano and consisting of thirty broad-band soundings along N-S and NW-SE oriented profiles. We found that the NE sector of the sliding volume, modeled by ground deformation data inversions and character- ized by the highest displacement velocity, is characterized low resistivity values and it is bounded by two seismic clusters. The northern one is clearly related to the Pernicana fault and it’s not deeper than 3 km b.s.l. while the second one is located southwards, beneath the northern wall of the Valle del Bove, not related to any evident struc- ture at the surface. An evident layer with very reduced seismicity lies at 3 km of depth and well corresponds to the simplified analytic models of a sliding planar surface resulting from GPS data inversions

Hydrothermal pressure-temperature control on CO2 emissions and seismicity at Campi Flegrei (Italy)

Fluids supplied by stored magma at depth are causal factors of volcanic unrest, as they can cause pressurization/heating of hydrothermal systems. However, evidence for links between hydrothermal pressurization, CO2 emission and volcano seismicity have remained elusive. Here, we use recent (2010−2020) observations at Campi Flegrei caldera (CFc) to show hydrothermal pressure, gas emission and seismicity at CFc share common source areas and well-matching temporal evolutions. We interpret the recent escalation in seismicity and surface gas emissions as caused by pressure-temperature increase at the top of a vertically elongated (0.3–2 km deep) gas front. Using mass (steam) balance considerations, we show hydrothermal pressurization is causing energy transfer from the fluids to the host rocks, ultimately triggering low magnitude earthquakes within a seismogenetic volume containing the hydrothermal system. This mechanism is probably common to other worldwide calderas in similar hydrothermal activity state

TiO2-SiO2-PMMA Terpolymer Floating Device for the Photocatalytic Remediation of Water and Gas Phase Pollutants

Floating photocatalytic devices are highly sought-after as they represent good candidates for practical application in pollutant remediation of large water basins. Here, we present a multilayer floating device for the photocatalytic remediation of contaminants present in water as well as of volatile species close to the water surface. The device was prepared on a novel tailored ter-polymer substrate based on methylmethacrylate, alpha-methylstyrene and perfluoroctyl methacrylate. The ad hoc synthesized support presents optimal characteristics in terms of buoyancy, transparency, gas permeability, mechanical, UV and thermal stability. The adhesion of the TiO2 top layer was favoured by the adopted casting procedure, followed by a corona pre-treatment and by the deposition of an intermediate SiO2 layer, the latter aimed also at protecting the polymer support from photocatalytic oxidation. The device was characterized by contact angle measurement, UV-vis transmittance and scanning electron microscopy. The final device was tested for the photocatalytic degradation of an emerging water pollutant as well as of vapors of a model volatile organic compound. Relevant activity was observed also under simulated solar irradiation and the device showed good stability and recyclability, prospecting its use for the photocatalytic degradation of pollutants in large water basins

Las representaciones gráficas en la formación de alumnos de la Carrera de Arquitectura de la FAU-UNNE. Arquitectura IV-UPC

El objetivo del presente trabajo es exponer los resultados preliminares del proyecto de investigación que estamos desarrollando, para conocer la manera en que los alumnos de arquitectura de nuestra universidad representan el objeto arquitectónico con métodos analógicos y digitales en la actualidad. Se busca contribuir a reformular y producir nuevas estrategias pedagógicas en el proceso de formación en representación para el diseño arquitectónico en la carrera de Arquitectura. Los resultados permiten conocer las habilidades y destrezas del estudiante en relación con los Sistemas de Representación a través de cortes transversales en cinco momentos de la cursada de la carrera durante los ciclos lectivos 2013 a 2016. Fundamentalmente nos explayamos en el Taller Virtual Red Norte Grande, experiencia innovadora y única del taller en Arquitectura IV UPC

Impacto del mundo digitial sobre las representaciones gráficas del diseño arquitectónico: la experiencia 2014 en el Taller Virtual de Arquitectura IV. UPC

Este trabajo expone los resultados preliminares del Proyecto de Investigación 12C006-2013-16 “Las Representaciones Gráficas en la formación de alumnos de la carrera de Arquitectura-UNNE”. Se busca expresar el impacto del mundo digital sobre las representaciones y conocer las habilidades y destrezas del estudiante en relación con los sistemas de representación a través de cortes transversales en cinco momentos de la carrera de Arquitectura (nivel ingresantes, primero, segundo, cuarto y sexto años). A través de una investigación cualitativa, descriptiva-explicativa, nos explayamos en el taller Virtual Red Norte Grande, experiencia innovadora única de taller colaborativo en la cátedra Arquitectura IV, UPC.

Electrical signatures of a permeable zone in carbonates hosting local geothermal manifestations: Insights for the deep fluid flow in the gargano area (South-eastern Italy)

In northern Apulia (Italy), geothermal evidence can be associated to structural conditions. The area is characterised by a thick calcareous and dolomitic succession, affected by seismogenic faults and karst dissolution, and by the presence of some surficial geothermal pieces of evidence (coastal springs and well waters). In order to contribute to a better understanding of the deep circulation, an audio-magnetotelluric (AMT) survey was carried out. Soundings were acquired at 22 sites along a 27-km long profile crosscutting the Gargano Promontory and the Tavoliere Plain. A 2D inversion was undertaken providing a resistivity model down to 3 km b.s.l.. In the Tavoliere Plain the resistivity mainly increases with depth. Towards the Gargano area, a low-resistivity layer is interpreted as a fracture network which may favour fluid circulation. The supposed geometry of the permeable zone matches well with the structural interpretation proposed by independent studies. Thus, the present AMT study enabled imaging the first order geological structures that channel deep fluids as locally recognised by boreholes and natural manifestations at the surface

A method to determine the magnetotelluric static shift from DC resistivity measurements in practice

Many efforts have been made to face magnetotelluric (MT) static shift. Impedance tensor analyses give insight to the presence of this feature and allow the determination of some parameters described by the MT distortion matrix. A quantitative determination of the full distortion matrix is, however, still difficult and needs additional measurements. In addition to MT, other electric and electromagnetic methods also are effected by static shift. Using direct current resistivity techniques, e.g., we can determine the static-shift factors in a simpler way because the sources can be controlled. Generally, because the distortion matrix has four entries, four additional quantities have to be determined to describe the static shift completely. They can be achieved, e.g., through measuring two orthogonal electric field components for two orthogonal source configurations. The source electrode spacing, however, has to be sufficiently large to resemble horizontal currents and match the MT plane-wave analog. The procedure at hand extracts the static-shift factors from multielectrode measurements after this condition is met. For the sake of simplicity and demonstration purposes, only inline measurements orthogonal to the strike direction of a 2D model are considered so that the vectorial problem reduces to a scalar one. This procedure is applied to a MT field data set in a regional 2D environment that shows only two additional quantities are necessary to determine the static shift

Granger causality analysis of geophysical, geodetic and geochemical observations during volcanic unrest: A case study in the campi flegrei caldera (Italy)

The recent signs of reawakening at Campi Flegrei caldera (Southern Italy) received a great deal of attention due to the issues related to the volcanic risk management in a densely populated area. This paper explores relations between ground deformations, seismicity and geochemical time series in the time span 2004–2016. The aim is to unravel primary processes of unrest and the related indicators which may change in time. Data structure and interactions among variables were examined applying the clustering analysis, the correlations and the Granger causality test. The hierarchical agglomerative clustering detected two sub-periods which were further investigated. In both sub-period causal links were observed between variables while correlations did not appear and vice versa. Thus, well established formal approaches are required to study causal relations. Granger test results indicate that during 2004–2011 the awakening unrest could be mainly ascribed to hydrothermal system pressure fluctuations, probably induced by deep-rooted fluids injection, and that ground deformation together with CO2 /H2 O appears the most suitable geo-indicators. The 2011–2016 sub-period is characterized by enhanced dynamical connectivity. Granger test results suggest that the unrest is driven by a more localized and shallower thermohydromechanical engine. CO/CO2, He/CH4 and ground deformation velocity are mutually interacting appearing the most suitable geo-indicators