262 research outputs found

    Evidences of a contractional pattern along the northern rim of the Hyblean Plateau (Sicily, Italy) from GPS data

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    In this paper we present the main results inferred from GPS data collected between 1998.00 and 2009.78 along the northern rim of the Hyblean Plateau from 9 continuous and 23 survey-mode sites. From a geological point of view, this area is of great interest because 1) it represents an important piece of the collision front between Nubia and Eurasia 2) it is very close to the biggest European volcano Mount Etna and 3) it has been hit by strong earthquakes in the past (1169 and 1693) that struggled the cities of Catania, Siracusa and Ragusa provoking tens of thousands of casualties. We have found that the ground deformation pattern clearly defines an area of prevailing contraction along the northern rim of the Hyblean Plateau with a maximum negative strain-rate of about 0.14µstrain/yr in agreement with both geological and Interferometric Synthetic Aperture Radar (InSAR) data. In addition, a transition to extensional regime is acting toward the central sector of the plateau. The velocity field referred to the Eurasian frame indicates that a large part of the plateau is dominated by a 5.4mm/yr northward motion

    Detection of Volcanic Plumes by GPS: the 23 November 2013 Episode on Mt. Etna

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    The detection of volcanic plumes produced during explosive eruptions is important to improve our under- standing on dispersal processes and reduce risks to aviation operations. The ability of Global Position-ing System (GPS) to retrieve volcanic plumes is one of the new challenges of the last years in volcanic plume de - tection. In this work, we analyze the Signal to Noise Ratio (SNR) data from 21 permanent stations of the GPS network of the Istituto Nazionale di Geofisica e Vulcanologia, Osservatorio Etneo, that are located on the Mt. Etna (Italy) flanks. Being one of the most explosive events since 2011, the eruption of November 23, 2013 was chosen as a test-case. Results show some variations in the SNR data that can be correlated with the presence of an ash-laden plume in the atmosphere. Benefits and limitations of the method are highlighted

    A Dynamic Bayesian Network for Mt. Etna Volcano State Assessment

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    Nowadays, the real-time monitoring of Mt. Etna volcano is mostly delegated to one or more human experts in volcanology, who interpret the data coming from different kind of monitoring networks. Among their duties, the evaluation of the volcano state is one of the most critical task for civil protection purposes. Unfortunately, the coupling of highly non-linear and complex volcanic dynamic processes leads to measurable effects that can show a large variety of different behaviors. Moreover, due to intrinsic uncertainties and possible failures in some recorded data the volcano state needs to be expressed in probabilistic terms, thus making the fast volcano state assessment sometimes impracticable for the personnel on duty at the 24h control room. With the aim of aiding the personnel on duty in volcano monitoring, here we present an expert system approach based on Bayesian networks to estimate automatically the ongoing volcano state from all the available different kind of measurements. A Bayesian network is a static probabilistic graphical model that represents a set of random variables and their conditional dependencies via a directed acyclic graph. We consider model variables both the measurements and the possible states of the volcano. In order to include the time in the model, we use a Dynamic Bayesian Network (DBN) which relates variables to each other over adjacent time steps. The model output consists of an estimation of the probability distribution of the feasible volcano states. We build the model by considering the long record of data from 2011 to 2014 and we cross-validate it by considering 3 years for parameter estimation and 1 year for testing in simulated real-time mode

    Assessing seismic efficiency from scalar Moment-rates: an application to Mt. Etna volcano (Italy)

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    Here we propose an improved estimation of the scalar seismic (from instrumental and historical catalogues), geodetic and geologic moment-rates for the eastern flank of Mt. Etna. The estimated moment-rates have been compared in terms of seismic efficiency. Results show that all the calculated efficiency values are lower than 40%, i.e., the geodetic moment-rate estimations are generally larger than the seismic and the geologic ones. Although a number of reasons may account for the observed discrepancy, we are confident that a large amount of the deformation affecting the eastern flank occurs aseismically

    Laser-generated nanoparticles to change physical properties of solids, liquids and gases

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    Synthesis of nanoparticles was possible employing a Nd: YAG pulsed laser at fundamental harmonic. The production of nanoparticles in water depends mainly on the laser parameters (pulse duration, energy, wavelength), the irradiation conditions (focal spot, repetition rate, irradiation time) and the medium where the ablation occurs (solid target, water, solution concentration). The nanoparticles can be introduced in solids, liquids or gases to change many physical characteristics. The optical properties of polymers and solutions, the wetting ability of liquids, the electron density of laser-generated plasma, represent some examples that can be controlled by the concentration of metallic nanoparticles (Au, Ag, Ti, Cu). Some bio-medical applications will be presented and discussed

    Etn@ref: a geodetic reference frame for Mt. Etna GPS networks

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    In volcanology, one of the most important instruments for scientific community interested in modelling the physical processes related to magma movements in the shallow crust is geodetic data. Since the end of the 1980s, GPS surveys and Continuous GPS stations (CGPS) have greatly improved the possibility to measure such movements with high time and space resolution. However, physical modelling requires that any external influence on the data, not directly related to the investigated quantity, must be filtered. One major tricky factor in determining a deformation field using GPS displacement vectors and velocities is the correct choice of a stable reference frame. In this work, using more than a decade of GPS measurements, we defined a local reference frame in order to refer the Mt. Etna ground deformation pattern to a rigid block. In particular, we estimated the Euler pole for the rigid block by minimizing, with a weighted least squares inversion, the adjustments to two horizontal components of GPS velocity at 13 “fiducial” sites located within 350 km around Mt. Etna. The inversion inferred an Euler pole located at 38.450° N and -107.702° E and a rotation rate of 0.263 deg/Myr

    Deliveries by caesarean sections on request of women: legal-medical evidence

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    Introduction: In Italy the use of caesarean delivery has a rising trend moving away from European standards appeared on Euro-Peristat on maternal and child health, presenting the highest percentage of use of this procedure with significant regional differences. This study have analyzed the most recent data of a Sicilian reality about normal delivery and caesarean sections carried out in a hospital situated in Messina (Italy). Materials and methods: A total number of 1,573 medical records from 1st January 2011 to 31st December 2013 were analyzed and data gathered were statistically examined to describe general and specific parameters of the sample making use of Epi Info 7.1.4 software (CDC Atlanta – USA). Chi-square test was used to show any statistic differences among studied population. Results: Overall data showed that were carried out 38.27% of spontaneous deliveries, 7.06% of induced labor, and 54.67% of caesarean deliveries. There were no significant statistical differences between recourse to caesarean section and vaginal delivery in relation to nationality, age, level of education and/or work. The enrolled group, based on the parameters examined, was divided into appropriate caesarean section, in 79.49% of cases, inappropriate in 7.20% (mother’s request) and unjustified in 13.31% (with no indication, incomplete medical record). An examination of the anesthetic medical records showed that the caesarean section was considered to be urgent in 31.74% of the cases; however in 17.92% of these cases there is no information in the medical records justifying the use of emergency procedures. Conclusion: The reported data from the study that we conducted, lead to medical-legal and juridical considerations, especially as regards the use of caesarean delivery on the woman request. The complexity of the phenomenon requires the development of a variety of intervention strategies, not only for issues related to the reduction of health care costs, but also with regard to the clinical risk management and medical legal aspects related to the several profiles of professional responsibility

    Production and characterization of micro-size pores for ion track etching applications

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    For many years the applications of ion track etch materials have increased considerably, like charged particles detection, molecular identification with nanopores, ion track filters, magnetic studies with nanowires and so on. Over the materials generally used as track detector, the Poly-Allyl-Diglycol Carbonate (PADC), offers many advantages, like its nearly 100 % detection efficiency for charged particle, a high resistance to harsh environment, the lowest detection threshold, a high abrasion resistance and a low production costs. All of these properties have made it particularly attractive material, even if due to its brittleness, obtaining a thin film (less than 500 μm) is still a challenge. In this work, PADC foils have been exposed to a-particles emitted by a thin radioactive source of 241Am and to C ions from the Tandetron 4130 MC accelerator. The latent tracks generated in the polymer have been developed using a standard etching procedure in 6.25 NaOH solution. The dependence of the ion tracks' geometry on the ion beam energy and fluence has been evaluated combining the information obtained through a semiautomatic computer script that selects the etched ion tracks according to their diameter and mean grey value and nanometric resolution images by atomic force microscopy
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