Progetto di un padiglione integralmente vitreo costruito mediante telai ibridi TVT di grande luce

La richiesta architettonica di una progressiva, completa smaterializzazione delle strutture portanti può essere soddisfatta solo entro certi limiti mediante l’impiego esclusivo di vetro strutturale. Quando a questa esigenza si aggiunge quella del superamento di grandi luci o grandi altezze è indispensabile ricorrere a sistemi costruttivi di tipo ibrido vetro-acciaio nei quali il vetro, fragile ma resistente a compressione, viene posto in associazione simbiotica con l’acciaio, duttile e resistente a trazione. Nella presente nota viene presentato lo studio di fattibilità di un padiglione integralmente vetrato costituito da una serie di telai trasversali ad alta trasparenza tamponati e controventati da pannelli vitrei ibridi precompressi. Le traverse dei portali, aventi circa 20 metri di luce, ed i piedritti, alti circa 8 metri, sono progettati mediante elementi del tipo TVT- bis (Travi Vitree Tensegrity). La capacità della costruzione di sostenere in sicurezza elevate condizioni di carico statico e dinamico è dimostrata attraverso analisi numeriche multi-scala tarate sulla base dei risultati sperimentali raccolti nelle campagne di test effettuati sui prototipi TVT e TVT e spinti fino a rottura. The architectural demand for a complete de-materialisation of load bearing structures can be satisfied only in limited cases with the exclusive structural use of glass. Otherwise, it is necessary to use hybrid glass-steel structures to achieve challenging applications as long spanned or high rise constructions. Hence, glass, fragile but highly compressive resistant, is associated with steel, ductile and tensile resistant. The present research presents the feasibility study for a fully glazed pavilion, made of six TVT-bis (Travi Vitree Tensegrity) portal frames and hybrid pre-stressed panels as bracing system. The frames are about 20 m spanned and 8 m height. The structural performance to withstand heavy static and dynamic loads is assessed by means of multiscalar FEM numerical analyses, calibrated on the collapse tests performed on TVT e TVT prototypes

Fingerprint Identification Using Noise in the Horizontal-to-Vertical Spectral Ratio: Retrieving the Impedance Contrast Structure for the Almaty Basin (Kazakhstan)

Detailed knowledge of the 3D basin structure underlying urban areas is of major importance for improving the assessment of seismic hazard and risk. However, mapping the major features of the shallow geological layers becomes expensive where large areas need to be covered. In this study, we propose an innovative tool, based mainly on single station noise recordings and the horizontal-to-vertical spectral ratio (H/V), to identify and locate the depth of major impedance contrasts. The method is based on an identification of so-called fingerprints of the major impedance discontinuities and their migration to depth by means of an analytical procedure. The method is applied to seismic noise recordings collected in the city of Almaty (Kazakhstan). The estimated impedance contrasts vs. depth profiles are interpolated in order to derive a three-dimensional (3D) model, which after calibration with some available boreholes data allows the major tectonic features in the subsurface to be identified

Geological 3D model of the Po Basin

The geological 3D model of the Po Basin includes the geometry of four stratigraphic horizons (top or unconformity) bounding lithological homogeneous successions of sedimentary units, in the Triassic - Pleistocene time interval, and 179 fault geometries. Each stratigraphic horizon is supplemented by its isobaths. Where possible, the thickness of the succession above or below, respectively for basal unconformity and top, is provided with the surface depth. The lithology, event process, and age of each sedimentary succession are also provided. Each fault, with its upper tip line, is supplemented with the kinematic, mean values for strike, dip azimuth, and dip derived from the 3D surface geometry, and the age of the oldest and youngest faulted or deformed stratigraphic horizon, if obtainable from the 3D geological model. This harmonized dataset and the related data model were obtained in the framework of the GO-PEG project, co-funded by the Connecting Europe Facility (CEF) of the European Commission. More specifically, this dataset is the output of the Go-Depth use case aiming to provide a methodology and a model to conceptualize, organize and deliver easy-to-use, high-quality, interoperable subsurface information for sustainable planning and use of natural resources. To this aim the data coming from European-funded projects GeoMol (Alpine Space Programme 2012-2015) and GeoERA HotLime (Horizon 2020, 2018-2021) has been used. In view of data interoperability, the data model has been developed as an extension of the INSPIRE Geology data model. The dataset is served through APIs conforming to the OGC API - Feature standard and it is also downloadable in GeoPackage format, anticipating the application of the principles established by the Open Data Directive (Directive (EU) 2019/1024) regarding the sharing of the High-Value Datasets. We acknowledge the listed researchers who contributed seismic and geological data interpretation to the GeoMol and HotLime Project

Deformation and Fault Propagation at the Lateral Termination of a Subduction Zone: The Alfeo Fault System in the Calabrian Arc, Southern Italy

The Calabrian Arc subduction, southern Italy, is a critical structural element in the geodynamic evolution of the central Mediterranean basin. It is a narrow, northwest-dipping slab bordered to the southwest by the Alfeo Fault System (AFS) and to the northeast by a gradual transition to a collision. We used a dense set of two-dimensional high-penetration (up to 12 s) multichannel seismic reflection profiles to build a three-dimensional model that spans the AFS for over 180 km of its length. We find that the AFS is made up of four deep-seated major blind segments that cut through the lower plate, offset the subduction interface, and only partially propagate upward across the accretionary wedge in the upper plate. These faults evolve with a scissor-like mechanism (mode III of rupture propagation). The shallow part of the accretionary wedge is affected by secondary deformation features well aligned with the AFS at depth but also mechanically decoupled from it. Despite the decoupling, the syn-tectonic Pliocene-Holocene deposits that fill in the accommodation space generated by the AFS activity at depth, constrain the age of inception of the AFS and allows us to estimate its throw and propagation rates. The maximum throw value is 6,000 m in the NW sector and decreases to the SE. Considering the age of faulting, the fault throw rate decreases accordingly from 2.31 mm/yr to 1 mm/yr. The propagation rate decreases from 62 mm/yr to 15 mm/yr during the Pliocene-Pleistocene, suggesting that also the Calabrian subduction process should have slowed down accordingly. The detailed spatial and temporal reconstruction of this type of faults can reveal necessary information about the evolution of subduction systems

Scattering Attenuation Images of the Control of Thrusts and Fluid Overpressure on the 2016–2017 Central Italy Seismic Sequence

Deep fluid circulation likely triggered the large extensional events of the 2016–2017 Central Italy seismic sequence. Nevertheless, the connection between fault mechanisms, main crustal-scale thrusts, and the circulation and interaction of fluids with tectonic structures controlling the sequence is still debated. Here, we show that the 3D temporal and spatial mapping of peak delays, proxy of scattering attenuation, detects thrusts and sedimentary structures and their control on fluid overpressure and release. After the mainshocks, scattering attenuation drastically increases across the hanging wall of the Monti Sibillini and Acquasanta thrusts, revealing fracturing and fluid migration. Before the sequence, low-scattering volumes within Triassic formations highlight regions of fluid overpressure, which enhances rock compaction. Our results highlight the control of thrusts and paleogeography on the sequence and hint at the monitoring potential of the technique for the seismic hazard assessment of the Central Apennines and other tectonic regions

Importance of earthquake rupture geometry on tsunami modelling: the Calabrian Arc subduction interface (Italy) case study

SUMMARY The behaviour of tsunami waves at any location depends on the local morphology of the coasts, the encountered bathymetric features, and the characteristics of the source. However, the importance of accurately modelling the geometric properties of the causative fault for simulations of seismically induced tsunamis is rarely addressed. In this work, we analyse the effects of using two different geometric models of the subduction interface of the Calabrian Arc (southern Italy, Ionian Sea) onto the simulated tsunamis: a detailed 3-D subduction interface obtained from the interpretation of a dense network of seismic reflection profiles, and a planar interface that roughly approximates the 3-D one. These models can be thought of as representing two end-members of the level of knowledge of fault geometry. We define three hypothetical earthquake ruptures of different magnitudes (Mw 7.5, 8.0, 8.5) on each geometry. The resulting tsunami impact is evaluated at the 50-m isobath in front of coastlines of the central and eastern Mediterranean. Our results show that the source geometry imprint is evident on the tsunami waveforms, as recorded at various distances and positions relative to the source. The absolute differences in maximum and minimum wave amplitudes locally exceed one metre, and the relative differences remain systematically above 20 per cent with peaks over 40 per cent. We also observe that tsunami energy directivity and focusing due to bathymetric waveguides take different paths depending on which fault is used. Although the differences increase with increasing earthquake magnitude, there is no simple rule to anticipate the different effects produced by these end-member models of the earthquake source. Our findings suggest that oversimplified source models may hinder our fundamental understanding of the tsunami impact and great care should be adopted when making simplistic assumptions regarding the appropriateness of the planar fault approximation in tsunami studies. We also remark that the geological and geophysical 3-D fault characterization remains a crucial and unavoidable step in tsunami hazard analyses

Editorial: Submarine Active Faults: From Regional Observations to Seismic Hazard Characterization

Since the beginning of the XXI Century, our society has witnessed a number of catastrophic earthquakes with devastating consequences (e.g., Sumatra 2004, Haiti 2010, Japan 2010, Nepal 2015, Italy 2009 and 2016). Localizing the active faults and understanding their earthquake history is key to improve modern probabilistic seismic hazard assessment (PSHA) and, thus, to mitigate the consequences of future events. Seismicity models to characterize the earthquake frequency in a region in PSHA studies have been traditionally based on archaeological, historical and instrumental earthquake records. However, the rapid advance of active tectonics and paleoseismological studies has resulted in the development of seismicity models for faults, since they allow characterizing the active faults, reconstructing their 3D geometry at depth, and determining their past earthquake history and seismic potential based on the interpretation of the geological record. Traditionally, active tectonics and paleoseismological research had been mainly conducted to study onshore active faults. However, the occurrence of the offshore Sumatra (2004) and Japan (2010) earthquakes and consequent tsunamis, which caused tens of thousands of casualties and extensive and severe damage and economic losses, have brought into sharp focus the need to better understand the geohazards related to submarine active faults. In the last few years, the availability of offshore geological and geophysical data at various scales (e.g., deep and shallow borehole, wide angle seismic profiles, tomography, 3D and 2D seismic reflection surveys, high resolution bathymetry or seafloor imaging) has allowed for a better definition of offshore fault systems. These studies focused on accurately constraining the kinematic, architecture and linkage of active faults, and, in some cases, identify recent earthquake ruptures or recognize and date individual events. In addition, underwater active tectonics and paleoseismological studies benefit from: (1) low erosional rates that preserve fault morphology and segmentation; (2) continuous sedimentation in time and space that allows for local and/or regional stratigraphic and chronostratigraphic correlations; (3) multiscale seafloor mapping and sub-seafloor seismic imaging; and 4) absence–or lowest amount–of human modification. This Research Topic includes fourteen published articles focused in the study of underwater active tectonic regions or active fault systems around the world (Figure 1). They use different datasets (i.e., bathymetry, seismicity from a local seismic network, sub-bottom profiling, reflection seismic profiles or sedimentary cores) to identify and characterize the seismic cycle of active faults using multidisciplinary approaches and innovative methodologies. The main goal of this Research Topic has been to show the present advance in underwater active tectonics and paleoseismology in order to improve our understanding about the seismic and tsunami hazard. Here we provide a short review of the contributions grouped by the main topics

Database of Individual Seismogenic Sources (DISS), Version 3.2.1: A compilation of potential sources for earthquakes larger than M 5.5 in Italy and surrounding areas

Istituto Nazionale di Geofisica e VulcanologiaPublished2T. Deformazione crostale attiva3T. Sorgente sismica4T. Sismicità dell'Italia5T. Sismologia, geofisica e geologia per l'ingegneria sismica6T. Studi di pericolosità sismica e da maremoto4IT. Banche dat

Decay resistance variability of European wood species thermally modified by industrial process

Thermal modification is now considered as a new ecofriendly industrial wood modification process improving mainly the material decay resistance and its dimensional stability. Most industrial thermal treatment processes use convection heat transfer which induces sometimes heterogeneous treatment temperature propagation within the oven and lead to the heterogeneity in treatment efficiency. Thus, it is common that treatment is not completely effective on several stack boards, in a same batch. The aim of this paper was to study the decay resistance variability of various European wood species thermally modified. Thermal modifications were performed around 240°C during 4h, on about 10 m3 of 27 x 152 x 2000 mm3 wood planks placed in an industrial oven having a volume of 20 m3, on the following wood species: spruce, ash, beech and poplar. All of the tests concerning the decay resistance were carried out in the laboratory using untreated beech and pine woods as reference materials. An agar block test was used to determine the resistance of thermally modified woods, leached beforehand according to EN 84 standard or not, to brown-rot and white-rot fungi, according to XP CEN/TS 15083-1. A large selection of treated wood samples was tested in order to estimate the variability of treatment efficiency. Thermal treatment increased the biological durability of all leached and un-leached modified wood samples, compared with native wood species. The treatment temperature of 240°C used in this study is sufficient to reach durability classes ''durable'' or ''very durable'' for the four wood species. However, the dispersion of weight loss values, due to the fungal attacks was very important and showed a large variability of the durability of wood which has been treated in a single batch. These results showed that there is a substantial need to develop process control and² indicator in order to insure that the quality of treated timber is properly evaluated with a view to putting this modified timber on the market under a chain of custody. (Résumé d'auteur

Environmental and Agro-Economic Sustainability of Olive Orchards Irrigated with Reclaimed Water under Deficit Irrigation

This study explores the effects of the adoption of reclaimed water (RW) as source of irrigation in conjunction with the application of deficit irrigation strategies in an olive orchard (different genotypes) located within the “Valle dei Margi” farmhouse (Eastern Sicily). Specifically, the RW was obtained in situ by treating the wastewater coming from the farmhouse throughout a treatment wetland system (TW). The effects of RW on crop water status (CWS) was assessed by conducting plant-based measurements (i.e., leaf water potential, Ψ, and leaves relative water content, RWC) and determining satellite-based biophysical indicators. An economical and environmental evaluation of the proposed sustainable irrigation practices was carried out by using the life cycle assessment (LCA) approach.The RW quality showed high variability due to fluctuations in the number of customers at the farmhouse during the Covid-19 pandemic period. However, high removal efficiency of the overall TW was reached even if the RW quality did not always accomplish with the limits of the Italian regulations. A strong impact in the variation of Ψ was observed among the olive orchard under the different water regimes, evidencing how CWS performances are greatly conditioned by the genotype. However, no differences in leaves RWC and in satellite-based biophysical indicators were detected, despite the severe water deficit imposed (i.e., 50% of irrigation water reduction). Finally, the results of the LCA analysis underlined that the use of RW may permit to obtain important gains both in economic and environmental terms, thus representing a valid strategy for the olive cultivation