1,722,372 research outputs found
Shallow dike emplacement and related hazard in central stratovolcanoes
No full textIn the crust, the orientation of a dike is controlled by the orientation of the principal stresses, with the dike orthogonal to the least compressive stress. At shallower levels, the presence of a volcanic edifice introduces significant deviations from expected patterns. The load of the edifice focuses the stresses above the
center of a magma chamber, promoting the development of a central vent system.
But the location and orientation of the dikes may be also controlled by the shape of the edifice, or by the presence of scarps along the volcano slopes, commonly produced by sector collapses. Therefore, while dike propagation in areas without prominent relief is usually controlled by regional
tectonism, the propagation of dikes in volcanic edifices depends upon the shape and topography of the edifice, as well as the stress conditions within shallow magma reservoirs.Published53-561.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani3.2. Tettonica attiva3.5. Geologia e storia dei vulcani ed evoluzione dei magmi3.6. Fisica del vulcanismo4.3. TTC - Scenari di pericolosità vulcanicaN/A or not JCRreserve
Il Respiro dell'Etna
No full textL’Etna è uno dei vulcani più studiati al mondo.
Sulle sue pendici hanno vissuto sin dall’antichità
numerosi popoli, che hanno tramandato
nella mitologia il loro modo di capire ed interpretare
i fenomeni vulcanici osservati, e spesso subiti.
È un vulcano dalla dinamica complessa, difficile da
decifrare. Ma è anche uno spettacolare laboratorio
scientifico naturale, perché erutta frequentemente,
è facile da osservare e si fa avvicinare fino alle sue
bocche sommitali, sempre attive, correndo rischi abbastanza
limitati.Published20-255.9. Formazione e informazioneN/A or not JCRreserve
Il Respiro dell'Etna
No full textL’Etna è uno dei vulcani più studiati al mondo.
Sulle sue pendici hanno vissuto sin dall’antichità
numerosi popoli, che hanno tramandato
nella mitologia il loro modo di capire ed interpretare
i fenomeni vulcanici osservati, e spesso subiti.
È un vulcano dalla dinamica complessa, difficile da
decifrare. Ma è anche uno spettacolare laboratorio
scientifico naturale, perché erutta frequentemente,
è facile da osservare e si fa avvicinare fino alle sue
bocche sommitali, sempre attive, correndo rischi abbastanza
limitati.Published20-255.9. Formazione e informazioneN/A or not JCRreserve
Dynamic feeder dyke systems in basaltic volcanoes
No full textIn this paper, we describe the 1809 eruption of Mt. Etna, Italy, which represents one historical rare case in which it is possible to observe details of the internal structure of the feeder system. This is possible thanks to the presence of two large pit craters located in the middle of the eruptive fracture field that allow studying a section of the shallow feeder system. Along the walls of one of these craters, we analysed well-exposed cross sections of the uppermost 15–20 m of the feeder system and related volcanic products. Here, we describe the structure, morphology and lithology of this portion of the 1809 feeder system, including the host rock which conditioned the propagation of the dyke, and compare the results with other recent eruptions. Finally, we propose the dynamic model of the magma behaviour inside a laterally-propagating feeder dyke, demonstrating how this dynamic triggered important changes in the eruptive style (from effusive/Strombolian to phreatomagmatic) during the same eruption. Our results are also useful for hazard assessment related to the development of flank eruptions, potentially the most hazardous type of eruption from basaltic volcanoes in densely urbanized areas, such as Mt. Etna.Published1-112T. Tettonica attiva2V. Dinamiche di unrest e scenari pre-eruttivi3V. Dinamiche e scenari eruttivi4V. Vulcani e ambiente6A. Monitoraggio ambientale, sicurezza e territorioN/A or not JCRope
The 2004-05 Etna eruption: implications for flank deformation and structural behaviour of the volcano
No full textThe development of the 2004-05 eruption at Etna (Italy) is investigated by means of field surveys, to define the current structural state of the volcano. In 2004-05, a fracture swarm, associated with 3 effusive vents, propagated downslope from the SE summit crater towards SE. Such a scenario is commonly observed at Etna, as a pressure increase within the central conduits induces the lateral propagation of most of the dikes downslope. Nevertheless, some unusual features of this eruption (slower propagation of fractures, lack of explosive activity and seismicity, oblique shear along the fractures) suggest a more complex triggering mechanism. A detailed review of the recent activity at Etna enables us to better define this possible mechanism. In fact the NW-SE trending fractures formed in 2004-05 constitute the south-eastern continuation of a N-S trending fracture system which started to develop in early 1998, to the east of the summit craters. The overall 1998-2005 deformation pattern forms therefore an arcuate feature, whose geometry and kinematics are consistent with the head of a shallow flank deformation on the E summit of Etna. Similar deformation patterns have also been observed in analogue models of deforming volcanic cones. In this frame, the 2004-05 eruption was possibly induced by a dike resulting from the intersection of this incipient fracture system with the SE Crater. A significant acceleration of this flank deformation may be induced by any magmatic involvement. The central conduit of the volcano is presently open, constantly buffering any increase in magmatic pressure and any hazardous consequence can be expected to be limited. A more hazardous scenario may be considered with a partial or total closing of the central conduit. In this case, magmatic overpressure within the central conduit may enhance the collapse of the upper eastern flank, triggering an explosive eruption associated with a landslide reaching the eastern lower slope of the volcano
Emissioni di radon dal suolo a Torre del Filosofo (Etna): aggiornamento dati alla ripresa dell’attività stromboliana del Cratere di Sud-Est (30-31 Agosto 2006)
No full textIl 12 Luglio 2005 è stata installata una sonda tipo “barasol” in località Torre del Filosofo (~2920 m sul
mare, alto fianco meridionale del vulcano Etna), finalizzata al monitoraggio in continuo del gas Radon (vedi rapporto
UFVG/074). Tali studi ricadono nell’ambito della Convenzione che l’INGV ha stipulato con il Dipartimento della Protezione
Civile (progetto V3_6/28 – Etna, coordinatori S. Gresta e P. Papale, resp. M. Neri), la cui prima fase è iniziata il 1° giugno
2005. In questa nota descriviamo i risultati ottenuti contemporaneamente alla ripresa dell’attività stromboliana al Cratere di
Sud-Est (vedi aggiornamenti sul sito http://www.ct.ingv.it/Etna2006/Main.htm).Istituto Nazionale di Geofisica e VulcanologiaUnpublishedope
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Limiting the temperature at the chimney-roof penetration: Innovative roof passage with fins and case to meet the latest European standards and enhance heat recovery
No full textTo prevent overheating and consequent fires, European regulations prescribe thermal tests to
determine the distance between chimney and combustible materials. Traditional installations are
characterized by insulating material at the chimney-roof penetration; however, under critical
conditions, including high gas temperatures, thick and insulating roofs, this does not ensure
safety. A recent revision of the regulations has been made in light of the increased thermal
resistance of building elements. The paper describes an experimental campaign on a marketable
device that ensures low temperatures at chimney-roof penetration, limits thermal bridges, and
improves heat recovery. Besides the thermal and energy issues, other relevant aspects have
been considered, such as marketability, ease of installation, and cost. This device consists of
conductive and insulating elements enclosed in a case: the conductive elements reduce the
roof temperature by dissipating part of the heat from the chimney and conveying it to both
the outdoor and indoor environments. By analyzing the roof temperatures detected in a test
where the critical chimney operating conditions have been reproduced, its effectiveness has
been experimentally demonstrated. A second test on a similar device without the conductive
elements has been also conducted. Finally, results have been compared to those in the
literature about tests performed on similar elements. Since results reveal that the external
case strongly influences heat transfer, very thick roofs must have chimney-roof penetrations
carefully designed to accommodate the latest devices. Designers of timber houses, manufacturers
of chimney flues, and standards organizations can benefit from the results presented in this
study
Cellulite: come combatterla con il Fitness
No full textLa parola cellulite è diventata nell'immaginario comune della nostra società l'emblema dell'inestetismno femminile per eccellenza, una sorta di nemico da vincere ad ogni costo. Questo testo vuole quindi fungere da supporto sia per il privato o l'atleta che vuole capire meglio e risolvere la PEFS, ma contemporaneamente un valido strumento ad uso dell'istruttore, del laureato in scienze motorie, del medico che intende approfondire le varie tematiche legate all'insorgenza e alla cura della cellulite
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