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Upon numerical testing of our earlier theoretical results, we found a trivial algebraic error in Boschi et al. (2019), that had an impact on the numerical results published in that article. In the following, we describe the error and summarize the corrections that should be applied to the results (Formula Presented) (Figure Presented) In a new study by our team that is currently in preparation, eq. (28) of Boschi et al. (2019) and eq. (2) from this study are both validated numerically; synthetic tests show that, after correcting the errors, attenuation models a(?) can be retrieved successfully through the inversion procedure described by Boschi et al. (2019).

Il saggio esamina le caratteristiche dei processi di delegittimazione politica in Gran Bretagna dalla seconda metà del XIX secolo alla vigilia della Prima guerra mondiale

Riflessione sulle trasformazioni in corso nella ricerca storica e sul ruolo della storia contemporanea

Il saggio indaga l'impatto del marxismo sugli avvenimenti storici dalla metà dell'800 ad oggi.

Riflessioni sul ruolo e le prospettive della storia contemporanea in Italia e in Europa

The termi delegitimization has fairly recently come into vogue in the public debate in Italy, and, outside the field of the social sciences, it has understandably been Italian historians who have first made deliberate, articulate use of this concept in historical argument.....

Unraveling the temperature distribution and composition of Earth's crust is key for understanding its origin, evolution, and mechanical behavior. Models of compressional (VP) and shear wave (VS) velocity are obtained from seismological studies and can be interpreted in terms of temperature and composition, using relationship defined through laboratory experiments. These empirical evidences often do not properly account for the effects driven by temperature, pressure, water content, and phase change of minerals. In this study, we use thermodynamic modeling to properly investigate the role of these variables in affecting seismic properties, as a tool to guide (joint) inversion and interpretation of geophysical data. We find that mineralogical phase transitions can be more seismically relevant than a change in chemical composition. In particular, the α-β quartz transition would cause a jump in acoustic impedance and VP/VSratio >8%, occurring in the 15-25 km depth range, depending on the thermal gradient. Moreover, in the case of a cold lower crust, the consumption of plagioclase in favor of high-velocity minerals might represent another relevant seismic discontinuity. Different chemical compositions proposed for the Italian crust would be seismically indistinguishable, since they give overlapping seismic properties. Values of VS< 3.6 km s-1would imply a strong contribution of sediments and/or partial melt. The VS/density ratio shows a narrow variability, suggesting that densities at depth can be directly derived in first approximation from VS.

La prima guerra mondiale non fu solo un conflitto tra potenze nazionali per imporre nuovi equilibri di supremazia territoriale, ma fu soprattutto il primo scontro totale per la definizione di una nuova identità europea. In questo senso, molti intellettuali dell'epoca lo compresero bene, si trattò, come si capì ben presto nel corso del conflitto, di una 'guerra per la costituzione', vale a dire per la definizione delle caratteristiche di fondo, e dunque anche etico-politiche, che avrebbero dovuto caratterizzare l'Europa del futuro.

Commento all'intervento di Christof Dipper sulla storiografia italiana

We evaluate the thermo-chemical state of the lower mantle by analysing the differences in the pattern of heterogeneity between shear and compressional velocity variations and the S–to–P heterogeneity ratio (RS/P=δlnVS/δlnVP) as mapped in our model SPani and in alternative joint models. Robust structural differences between VP and VS evidence the presence of compositional heterogeneity within the two Large Low Shear Velocity Provinces (LLSVPs). We find also an increasing decorrelation with depth that can be associated with compositional layering of the LLSVPs. In addition, our model shows heterogeneity in the transition zone and mid mantle by complex morphology of subducting slabs and further differences between VP and VS that point to an unexpected heterogeneous lower mantle. Precise estimates of compositional heterogeneities are not yet affordable because of the difficulty to provide quantitative measure of RS/P, making it difficult to use this ratio to evaluate chemical heterogeneity. For instance, RS/P global median value () drops from ~2.8 to ~1.9, at 2500 km depth when the VP component of SPani is replaced by a VP model resulting from a differently regularized inversion and obtaining an equally good data fit. An increase of 20% of the SPani VP anomalies also drastically reduces without significantly degrading the data fit. Noise in model parameters also leads to overestimate RS/P in the two LLSVPs as we show with synthetic tests. Additional mineral physics uncertainties for compositional effects on RS/P and for the conversion of δlnVS and δlnVP into density further complicates a precise chemical interpretation.

We present an Integrated Geophysical Acquisition and Processing System (IGAPS) designed as a combined layout of high-technology equipments, each responding to definite physical principles and operating techniques, but all together constituting a one-purpose modern mobile geophysical work station. Such a multi-methodological and multi-parametric system is in fact planned to satisfy in principle in the most complete way the demand of physical and geometrical information concerning the ever exciting hidden world of any Cultural Heritage composite environment.

Multi-method surveys have been used with the aim of detecting either sharp discontinuities (boundary of the cavity, fractures in the medium, etc.) or volumetric variations (bodies with different physical properties), at three different archaeological test sites. For the survey a combination of passive and active methods (magnetic, GPR and dipole–dipole geoelectric method) has been used. With all methods a high-resolution data acquisition method has been adopted with the aim of reconstructing a global vision of the area investigated. The enhancement of the processing technique towards the integration of different geophysical methods, enabling one to better define the location, depth and geometry of any archaeological body, has been adopted. Copyright. © 2000 John Wiley and Sons, Ltd.

Equation-of-state (EOS) modeling, whereby the seismic properties of a specified thermochemical structure are constructed from mineral physics constraints, and compared with global seismic data, provides a potentially powerful tool for distinguishing between plausible mantle structures. However, previous such studies at lower mantle depths have been hampered by insufficient evaluation of mineral physics uncertainties, overestimation of seismic uncertainties, or biases in the type of seismic and/or mineral physics data used. This has led to a wide, often conflicting, variety of models being proposed for the average lower mantle structure. In this study, we perform a thorough reassessment of mineral physics and seismic data uncertainties. Uncertainties in both the type of EOS, and mineral elastic parameters, used are taken into account. From this analysis, it is evident that the seismic variability due to these uncertainties is predominantly controlled by only a small subset of the mineral parameters. Furthermore, although adiabatic pyrolite cannot be ruled out completely, it is problematic to explain seismic velocities and gradients at all depth intervals with such a structure, especially in the interval 1660-2000 km. We therefore consider a range of alternative thermal and chemical structures, and map out the sensitivity of average seismic velocities and gradients to deviations in temperature and composition. Compositional sensitivity is tested both in terms of plausible end-member compositions (e.g., MORB, chondrite), and via changes in each of the five major mantle oxides, SiO2, MgO, FeO, CaO, and Al2O3. Fe enrichment reduces both P and S velocities significantly, while Si enrichment (and Mg depletion) increases P and S velocities, with a larger increase in P than in S. Using purely thermal deviations from adiabatic pyrolite, it remains difficult to explain simultaneously all seismic observations. A superadiabatic temperature gradient does improve the seismic fit in the lowermost mantle, but should be accompanied by concurrent bulk chemistry changes. Our results suggest that the most plausible way to alter bulk chemistry in the lowermost mantle, simultaneously fitting density, bulk velocity and shear velocity constraints, is an increasing contribution of a hot, basalt-enriched component with depth. Copyright 2009 by the American Geophysical Union.

The fundamental geophysical goal in archaeological prospection, in near-surface investigations and generally in environmental applications is to construct as complete as possible maps of subsurface targets. The main effort in archaeology is also the integration of different, absolutely non-invasive techniques, especially if they are used in the high-resolution three-dimensional tomographic mode. In the present work a combination of fluxgate differential magnetic, ground penetrating radar and dipole–dipole geoelectric methods has been used with the aim of detecting superficial structures (wall remains and traces of an ancient road) contained in an archaeological test area (ancient Acropolis of Veio, Rome). With all geophysical techniques a high-resolution data acquisition method has been adopted with the aim of reconstruction of a global vision of the area investigated (20 m×20 m). Some signal processing and tomographic representation techniques have been used for data elaboration and interpretation. The results of the geophysical surveys have been confirmed by direct archaeological excavations carried out only at anomalous zones. © 1997 John Wiley and Sons, Ltd.

Proceedings of the First International Congress on Science and Technology for the Safeguard of Cultural Heritage in the Mediterranean Basin

International audience

Temperature distribution at depth is of key importance for characterizing the crust, defining its mechanical behavior and deformation. Temperature can be retrieved by heat flow measurements in boreholes that are sparse, shallow, and have limited reliability, especially in active and recently active areas. Laboratory data and thermodynamic modeling demonstrate that temperature exerts a strong control on the seismic properties of rocks, supporting the hypothesis that seismic data can be used to constrain the crustal thermal structure. We use Rayleigh wave dispersion curves and receiver functions, jointly inverted with a transdimensional Monte Carlo Markov Chain algorithm, to retrieve the VS and VP/VS within the crust in the Italian peninsula. The high values (>1.9) of VP/VS suggest the presence of filled-fluid cracks in the middle and lower crust. Intracrustal discontinuities associated with large values of VP/VS are interpreted as the α−β quartz transition and used to estimate geothermal gradients. These are in agreement with the temperatures inferred from shear wave velocities and exhibit a behavior consistent with the known tectonic and geodynamic setting of the Italian peninsula. We argue that such methods, based on seismological observables, provide a viable alternative to heat flow measurements for inferring crustal thermal structure.

The evolution of the Sicily Channel Rift Zone (SCRZ) is thought to accommodate the regional tectonic stresses of the Calabrian subduction system. Much of the observations we have today are either limited to the surface or to the upper crust or deeper from regional seismic tomography, missing important details about the lithospheric structure and dynamics. It is unclear whether the rifting is passive from far-field extensional stresses or active from mantle upwelling beneath. We measure Rayleigh-and Love-wave phase velocities from ambient seismic noise and invert for 3-D shear-velocity and radial anisotropic models. Variations in crustal S-velocities coincide with topographic and tectonic features. The Tyrrhenian Sea has a similar to 10 km thin crust, followed by the SCRZ (similar to 20 km). The thickest crust is beneath the Apennine-Maghrebian Mountains (similar to 55 km). Areas experiencing extension and intraplate volcanism have positive crustal radial anisotropy (V-SH > V-SV); areas experiencing compression and subduction-related volcanism have negative anisotropy. The crustal anisotropy across the Channel shows the extent of the extension. Beneath the Tyrrhenian Sea, we find very low sub-Moho S-velocities. In contrast, the SCRZ has a thin mantle lithosphere underlain by a low-velocity zone. The lithosphere-asthenosphere boundary rises from 60 km depth beneath Tunisia to similar to 33 km beneath the SCRZ. Negative radial anisotropy in the upper mantle beneath the SCRZ is consistent with vertical mantle flow. We hypothesize a more active mantle upwelling beneath the rift than previously thought from an interplay between poloidal and toroidal fluxes related to the Calabrian slab, which in turn produces uplift at the surface and induces volcanism.

Il saggio analizza i percorsi di delegittimazione utilizzati dalla classe politica liberale dagli anni '60 alla fine dell'800. Si è preso in esame linguaggi e argomenti impiegati in occasione dei conflitti elettorali.

Introduzione e al tema e al concetto di delegittimazione politica nell'Europa contemporanea

Modelling the response of seismic wavefields to sharp lateral variations in crustal discontinuities is essential for the application of seismic tomography and the correction of path effects in earthquake source characterization. Researchers generally focus on travel times and amplitudes of a limited number of phases, simplifying the underlying physics and reducing computational times. However, this approach offers insufficient resolution across oceanic basins while leaving a large part of the information contained in seismic records unexploited. Here, we model the sensitivity of wave propagation to crustal structural variations in the Southern Tyrrhenian basin by fitting the data produced by the Accumoli earthquake (Central Italy, 2016) and recorded at the national INGV (Istituto Nazionale di Geofisica e Vulcanologia) network. As a result, we reconstruct the velocity, Moho, and sediment structures in the basin and improve estimates of earthquake-source characteristics. P-, S- and coda-wave are first modelled and fitted to data acquired by a single station in Sicily; then, the procedure is extended to seismic receivers of the INGV network that contour the basin. The optimal fits are obtained using a deep Moho (~ 18 km) in the middle of the basin and a crustal pinch between the basin and the continental crust in Sicily. The deep Moho corresponds to the Issel Bridge, a portion of continental crust trapped between the Vavilov and Marsili volcanic centres. The Accumoli earthquake is optimally described using a boxcar source time function with a rise time of 6 s, a depth of 7.3 km, and the radiation pattern previously identified by INGV. Correlation analyses performed on data recorded across the network demonstrate the improvement in P-, S- and coda waveform fitting relative to previous Moho models obtained inverting single-phase observations. The early S-wave coda comprises trapped and reverberating phases that are particularly sensitive to crustal interfaces. With our approach, full-waveform simulations become a viable strategy for the inversion of Moho depths across the Southern Tyrrhenian using regional earthquakes.

Modelling regional-scale attenuation of seismic waves at ~1 Hz is challenging, especially when these waves propagate across both continental and oceanic crust. Recent developments in seismic imaging and modelling have provided us with the computational tools necessary to reconstruct these mixed settings using deterministic (coherent) and stochastic (coda) information. Here, we present new tomographic maps of coda-attenuation for both the Italian peninsula and the Tyrrhenian Sea. Kernel-based coda attenuation imaging in the diffusive approximation is tested in the oceanic environment, highlighting a non-diffusive behaviour across the Southern Tyrrhenian Sea. Joint deterministic and Radiative Transfer forward modelling of coherent and scattered waves (Radiative3D) is then performed for the portion of this area showing the lowest coda attenuation. The corresponding parametric study shows that coda attenuation is an efficient marker of variations of Moho depths and crustal reverberations, such as those we observe in a transitional area (characterized by continental crust and thicker Moho) between two oceanic basins (Vavilov and Marsili). Diffusive tomographic imaging informed by Radiative3D modelling reconstructs high-attenuation patterns along the Italian peninsula in agreement with the thick sediments cover across the Po Plain and the Adriatic coast and the magmatic systems in the Central Campanian province. A combined approach of coda-attenuation imaging and modelling can constrain Moho depth and spatial variations of seismic attenuation at regional scale and in mixed continental-oceanic settings.

Il capoluogo lombardo fu l’epicentro per eccellenza dei conflitti sociali dell’epoca, per la sua influenza nella vita italiana e il rilevante peso in molti settori strategici. Dall’inizio dell’autunno caldo fino alla strage di piazza Fontana, con il crescere delle agitazioni operaie con gli scontri sempre più violenti e frequenti nel centro della città si viene formando un’atmosfera diversa, un clima sempre più acceso, che finisce per avere il sopravvento. Il contributo analizza queste tematiche inserendole nel processo che sofcerà infine nella nascita delle Brigate rosse.

The active tectonic processes in convergent margins confer a high degree of complexity to the crust. Determining the thermal structure is, therefore, key to better elucidate the nature of those processes. In order to reconstruct the thermal structure of the crust beneath the Italian peninsula, we combine the most recent and accurate shear-wave velocity model that is currently available with thermodynamic modelling, assuming a global average crustal composition with no lateral variations. Our model, presented in terms of Moho temperature and crustal thermal gradients, shows a very good agreement with the known thermal anomalies associated with the backarc spreading related to the Apennine subduction. Importantly, we envisage a new anomalous region of high Moho temperatures in NW Italy (T > 800 °C at 30 km), at the transition between the Alps and Apennine orogens. The lowest temperatures of our model, corresponding to geothermal gradients

Deep within Earth's interior, in the brittle lithosphere and in the viscous asthenosphere below it, magma collects and ultimately feeds erupting volcanoes on Earth's surface. This magma holds keys to understanding the processes that create island chains like Hawaii. However, scientists can map the mantle--or any part of Earth's interior--only by using remote sensing techniques. The most important such technique is seismic tomography. Similar to medical computerized tomography (CT) scanning, seismic tomography allows scientists to construct three-dimensional images of deep Earth from observations of seismic waves that have passed through it. The speed of these waves varies depending on the composition, phase, temperature, and pressure of the material through which they travel. Analyzing seismic waves can thus reveal details of these deep materials. Were it not for seismology, we would be almost totally ignorant of the structure of the deep interior of Earth. The term "seismic tomography" was first coined by Adam Dziewonski and Don L. Anderson [Dziewonski and Anderson, 1984]. Over subsequent decades, the method has received substantial research funding, and the results have profoundly influenced our knowledge of Earth's structure and dynamics. Nevertheless, communicating the technique's limitations between subdisciplines within Earth science remains a challenge. For reasons of space and other factors, published papers often tend to deemphasize important caveats [Foulger et al., 2013]. The bottom line is that scientists tend to underestimate pitfalls and often have disproportionate faith in results.